Separators have been gaining increasing attention to improve the performance of lithium ion batteries(LIBs),especially for high safe and long cycle life.However,commercial polyolefin separators still face the problems...Separators have been gaining increasing attention to improve the performance of lithium ion batteries(LIBs),especially for high safe and long cycle life.However,commercial polyolefin separators still face the problems of rapid capacity decay and safety issues due to the poor wettability with electrolytes and low thermal stability.Herein,a novel composite separator is proposed by introducing a surfactant of sodium dodecyl thiosulfate(SDS)into the polytetrafluoroethylene(PTFE)substrate with the binder of polyacrylic acid(PAA)through the suction filtration method.The introduction of PAA/SDS enhances the adsorption energy between PTFE substrate and electrolyte through density functional theory calculations,which improves wettability and electrolyte uptake of the separator significantly.The asachieved composite separator enables the LIBs to own high Li^(+)conductivity(0.64×10^(-3)S cm^(-1))and Li^(+)transference number(0.63),further leading to a high capacity retention of 93.50%after 500 cycles at 1 C.In addition,the uniform and smooth surface morphology of Li metal employed the composite separator after cycling indicates that the lithium dendrites can be successfully inhibited.This work indicates a promising route for the preparation of a novel composite separator for high safe LIBs.展开更多
The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate f...The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate frameworks-8(ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances.In this work, the carbonized ZIF-8(C_(ZIF-8)) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/C_(ZIF-8) sample. The N_2 adsorption and desorptionisotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/C_(ZIF-8) cathode-active material delivers a discharge specific capacity of 159.3 m Ah g^(-1) at 0.1 C and a discharge specific energy of 141.7 m Wh g^(-1) after 200 cycles at 5.0 C(the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity,the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/C_(ZIF-8) cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.展开更多
Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are stil...Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene(Ni Co-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 ? can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and Ni Co-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected,the discharge capacity of 562 m Ah g-1 at 5.0 A g-1 for 800 cycles without degradation can be achieved,rate capability and cycle performance are better than that of NiCo-LDH(~100 mAh g-1). Furthermore, the density function theory(DFT) calculations were performed to demonstrate that Ni Co-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.展开更多
The rate performance and cycle stability of graphitized needle coke(GNC)as anode are still limited by the sluggish kinetics and volume expansion during the Li ions intercalation and de-intercalation process.Especially...The rate performance and cycle stability of graphitized needle coke(GNC)as anode are still limited by the sluggish kinetics and volume expansion during the Li ions intercalation and de-intercalation process.Especially,the output of energy density for lithium ion batteries(LIBs)is directly affected by the delithiation capacity below 0.5 V.Here,the mildly expanded graphitized needle coke(MEGNC)with the enlarged interlayer spacing from 0.346 to 0.352 nm is obtained by the two-step mild oxidation intercalation modification.The voltage plateau of MEGNC anode below 0.5 V is obviously broadened as compared to the initial GNC anode,contributing to the enhancement of Li storage below the low voltage plateau.Moreover,the coin full cell and pouch full cell configured with MEGNC anode exhibit much enhanced Li storage ability,energy density and better cycling stability than those full cells configured with GNC and commercial graphite anodes,demonstrating the practical application value of MEGNC.The superior anode behaviors of MEGNC including the increased effective capacity at low voltage and superior cyclic stability are mainly benefited from the enlarged interlayer spacing,which not only accelerates the Li ions diffusion rate,but also effectively alleviates the volume expansion and fragmentation during the Li ions intercalation process.In addition,the above result is further confirmed by the density functional theory simulation.This work provides an effective modification strategy for the NC-based graphite to enhance the delithiation capacity at a low voltage plateau,dedicated to improving the energy density and durability of LIBs.展开更多
Porous core–shell CoMn_2O_4 microspheres of ca. 3–5 μm in diameter were synthesized and served as anode of lithium ion battery. Results demonstrate that the as-synthesized CoMn_2O_4 materials exhibit excellent elec...Porous core–shell CoMn_2O_4 microspheres of ca. 3–5 μm in diameter were synthesized and served as anode of lithium ion battery. Results demonstrate that the as-synthesized CoMn_2O_4 materials exhibit excellent electrochemical properties. The CoMn_2O_4 anode can deliver a large capacity of 1070 mAh g^(–1) in the first discharge, a reversible capacity of 500 mAh g^(–1) after 100 cycles with a coulombic efficiency of 98.5%at a charge–discharge current density of 200 mA g^(–1), and a specific capacity of 385 mAh g^(–1) at a much higher charge-discharge current density of 1600 mA g^(–1). Synchrotron X–ray absorption fine structure(XAFS) techniques were applied to investigate the conversion reaction mechanism of the CoMn_2O_4 anode.The X–ray absorption near edge structure(XANES) spectra revealed that, in the first discharge–charge cycle, Co and Mn in CoMn_2O_4 were reduced to metallic Co and Mn when the electrode was discharged to 0.01 V, while they were oxidized respectively to CoO and MnO when the electrode was charged to 3.0 V.Experiments of both XANES and extended X–ray absorption fine structure(EXAFS) revealed that neither valence evolution nor phase transition of the porous core–shell CoMn_2O_4 microspheres could happen in the discharge plateau from 0.8 to 0.6 V, which demonstrates the formation of solid electrolyte interface(SEI) on the anode.展开更多
Binary carbon mixtures, carbon black ECP 600JD(ECP) combined with vapor grown carbon fiber(VGCF) or carbon nanotube(CNT), or graphene(Gr) in different mass ratios, are investigated as the conductive additives for the ...Binary carbon mixtures, carbon black ECP 600JD(ECP) combined with vapor grown carbon fiber(VGCF) or carbon nanotube(CNT), or graphene(Gr) in different mass ratios, are investigated as the conductive additives for the cathode material polyoxomolybadate Na_3[AlMo_6O_(24)H_6](NAM). Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy show that the surfaces of NAM particles are covered homogeneously with the binary conductive additive mixtures except the combination of ECP and CNT. The optimum combination is the mixture of ECP and VGCF, which shows higher discharge capacity than the combinations of ECP and CNT or Gr. Initial discharge capacities of 364, 339, and 291 m A·h/g are obtained by the combination of ECP and VGCF in the mass ratios of 2:1, 1:1, and 1:2, respectively. The results of electrochemical impedance spectra and 4-pin probe measurements demonstrate that the combination of ECP and VGCF exhibits the highest electrical conductivity for the electrode.展开更多
In this study, novel Carbon aerogel (CA)/Co<sub>3</sub>O<sub>4</sub>/Carbon (C) composites with a double protective structure are synthesized through a solvothermal method and in-situ polymeriz...In this study, novel Carbon aerogel (CA)/Co<sub>3</sub>O<sub>4</sub>/Carbon (C) composites with a double protective structure are synthesized through a solvothermal method and in-situ polymerization. The morphology and structure are characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR). The loading content of active anode material <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> in the composite is investigated by thermogravimetry, and the electrochemical properties of the composite are characterized by electrochemical impedance spectroscopy (EIS). The SEM results show that the nano-sized spherical <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> particle is adhered to the inner Carbon aerogel (CA). The HRTEM result indicates the thickness of the prepared Carbon (C) up to 40 nm. Nano-sheet is coated on the surface of the <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> particle. Compared with the pure <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> anode materials, the Carbon aerogel (CA)/<span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub>/Carbon (C) composites have better transport kinetics for both electron and lithium-ion in EIS testing results, which may contribute to its higher specific capacity and higher first coulomb efficiency. Due to the unique structure of the composite material with double protection against the volume expansion of <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> when charged, the Carbon aerogel (CA)/<span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub>/Carbon (C) composite material exhibits better cycle stability with a discharge capacity of 1180 mAh/g after 50 cycles. Therefore, the double protection strategy is verified as an effective method to improve the electrochemical performance of transition metal oxide with carbon composite as an anode material in lithium battery.展开更多
Coating slurries for making anodes and cathodes of lithium batteries contain a large percentage of solid particles of different chemicals, sizes and shapes in highly viscous media. A thorough mixing of these slurries ...Coating slurries for making anodes and cathodes of lithium batteries contain a large percentage of solid particles of different chemicals, sizes and shapes in highly viscous media. A thorough mixing of these slurries poses a major challenge in the battery manufacturing process. Several types of mixing devices and mixing methods were examined. The conventional turbine stirrers or ball mill mixers could be adequately used for the preparation of anode slurries, but not suitable for cathode slurries. In this study, a newly three-dimensional mixer, in conjunction with a multi-stage mixing sequence was proposed. The mixing effectiveness was examined by means of rheological measurements and flow visualization techniques. Preliminary electrical performance results indicated that the battery obtained using the 3D mixing device with a multi-stage mixing sequence was more efficient to those obtained from conventional methods.展开更多
Anode material for lithium ion battery is prepared by chemical oxidation of natural graphite. After oxidation. the propel-ties of natural graphite are modified, such as surface structure. the content of graphite phase...Anode material for lithium ion battery is prepared by chemical oxidation of natural graphite. After oxidation. the propel-ties of natural graphite are modified, such as surface structure. the content of graphite phases, the number of micropores and its stability. thus the modified natural graphite can be used as anode material for commercial lithium ion battery. The reversible capacity is increased from 100 mAh/g to above 300 mAh/g, and its cycling property is also satisfactory.展开更多
W-doped Li4Ti5O12 in the form of Li4Ti4.95W0.05O12 was firstly synthesized via solid state reaction. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize the structure and morph...W-doped Li4Ti5O12 in the form of Li4Ti4.95W0.05O12 was firstly synthesized via solid state reaction. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize the structure and morphology of Li4Ti4.95W0.05O12 . W-doping does not change the phase composition and particle morphology, while remarkably improves its cycling stability at high charge/discharge rate. Li4Ti4.95W0.05O12 exhibits an excellent rate capability with a reversible capacity of 131.2 mA·h/g at 10C and even 118.6 mA·h/g at 20C. The substitution of W for Ti site can enhance the electronic conductivity of Li4Ti5O12 via the generation of mixing Ti4+/Ti3+ , which indicates that Li4Ti4.95W0.05O12 is promising as a high rate anode for the lithium-ion batteries.展开更多
In order to improve the electrochemical performance and thermal stability of Li_(1.05)Co_(1/3)Ni_(1/3)Mn_(1/3)O_2 materials,Li_(1.05)Co_(0.3)Ni_(0.35)Mn_(0.3)M_(0.05)O_2(M=Ge,Sn)cathode materials were synthesized via ...In order to improve the electrochemical performance and thermal stability of Li_(1.05)Co_(1/3)Ni_(1/3)Mn_(1/3)O_2 materials,Li_(1.05)Co_(0.3)Ni_(0.35)Mn_(0.3)M_(0.05)O_2(M=Ge,Sn)cathode materials were synthesized via co-precipitation method.The structure,electrochemical performance and thermal stability were characterized by X-ray diffraction(XRD),charge/discharge cycling,cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential scanning calorimetry(DSC).ESEM showed that Sn-doped and Ge-doped slightly increased the size of grains.XRD and CV showed that Sn-doped and Ge-doped powders were homogeneous and had the better layered structure than the bare one.Sn-doped and Ge-doped improved high rate discharge capacity and cycle-life performance.The reason of the better cycling performance of the doped one was the increasing of lithium-ion diffusion rate and charge transfer rate.Sn-doped and Ge-doped also improved the mateials thermal stability.展开更多
Mb2O5 -carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source,and studied as an anode material for high-performance lithium ion battery.The structural cha...Mb2O5 -carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source,and studied as an anode material for high-performance lithium ion battery.The structural characterizations reveal that the nanocomposite possesses a core-shell structure with a thin layer of carbon shell homogeneously coated on the Nb2O5 nanocrystals.Such a unique structure enables the composite electrode with a long cycle life by preventing the Nb2O5 from volume change and pulverization during the charge-discharge process. In addition,the carbon shell efficiently improves the rate capability.Even at a current density of 500 mA·g-1,the composite electrode still exhibits a specific capacity of～100 mAh·g-1.These results suggest the possibility to utilize the Nb2O5-carbon core-shell composite as a high performance anode material in the practical application of lithium ion battery.展开更多
This paper investigates the mechanism of Li insertion into interphase Ni3Sn in Ni-Sn alloy for the anode of lithium ion battery by means of the first-principles plane-wave pseudopotential.Compared with other phases,it...This paper investigates the mechanism of Li insertion into interphase Ni3Sn in Ni-Sn alloy for the anode of lithium ion battery by means of the first-principles plane-wave pseudopotential.Compared with other phases,it is found that the Ni3Sn has larger relative expansion ratio and lower electrochemical potential,with its specific plateaus voltage around 0.3 eV when lithium atoms are filled in all octahedral interstitial sites,and the relative expansion ratio increasing dramatically when the lithiated phase transits from octahedral interstitial sites to tetrahedral interstitial sites.So this phase is a devastating phase for whole alloy electrode materials.展开更多
Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images i...Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn_(0.6)Fe_(0.4)PO_4(S2)was about 80 nm in diameter.The discharge capacity of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn_(0.6)Fe_(0.4)PO_4 and it in situ reduction of GO could improve the electrical conductivity of LiMn_(0.6)Fe_(0.4)PO_4 material.展开更多
Sn thin film on Cu foil substrate as the anode of lithium ion battery was prepared by direct current magnetron sputtering(DCMS). The surface morphology,composition and thickness and the electrochemical behaviors of th...Sn thin film on Cu foil substrate as the anode of lithium ion battery was prepared by direct current magnetron sputtering(DCMS). The surface morphology,composition and thickness and the electrochemical behaviors of the prepared Sn thin film were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),inductively coupled plasma atomic emission spectrometry(ICP),cyclic voltammetry(CV) and galvanostatic charge/ discharge(GC) measurements. It is found that the Sn film is consists of pure Sn with an average particle diameter of 100 nm. The thickness of the film is about 320 nm. The initial lithium insertion capacity of the Sn film is 771 mA·h/g. The reversible capacity of the film is 570 mA·h/g and kept at 270 mA·h/g after 20 cycles.展开更多
A novel bismuth–carbon composite, in which bismuth nanoparticles were anchored in a nitrogen-doped carbon matrix(Bi@NC), is proposed as anode for high volumetric energy density lithium ion batteries(LIBs).Bi@NC compo...A novel bismuth–carbon composite, in which bismuth nanoparticles were anchored in a nitrogen-doped carbon matrix(Bi@NC), is proposed as anode for high volumetric energy density lithium ion batteries(LIBs).Bi@NC composite was synthesized via carbonization of Zn-containing zeolitic imidazolate(ZIF-8) and replacement of Zn with Bi, resulting in the N-doped carbon that was hierarchically porous and anchored with Bi nanoparticles. The matrix provides a highly electronic conductive network that facilitates the lithiation/delithiation of Bi.Additionally, it restrains aggregation of Bi nanoparticles and serves as a buffer layer to alleviate the mechanical strain of Bi nanoparticles upon Li insertion/extraction.With these contributions, Bi@NC exhibits excellent cycling stability and rate capacity compared to bare Bi nanoparticles or their simple composites with carbon. This study provides a new approach for fabricating high volumetric energy density LIBs.展开更多
N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers have been successfully synthesized according to a facile solvothermal/hydrothermal method.The obtained CNTs@α-Fe_2O_3@C nanofibers composites exhibited special three-dimen...N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers have been successfully synthesized according to a facile solvothermal/hydrothermal method.The obtained CNTs@α-Fe_2O_3@C nanofibers composites exhibited special three-dimensional(3-D)network structure,which endows they promising candidate for anode materials of lithium ion battery.The coaxial property of CNTs@α-Fe_2O_3@C nanofibers could significantly improve the cycling and rate performance owing to the acceleration of charge/electron transfer,improvement of conductivity,maintaining of structural integrity and inhibiting the aggregation.Theα-Fe_2O_3nanoparticles with small size and high percentage of N-doped amount could further improve the electrochemical performance.As for the CNT@α-Fe_2O_3@C nanofibers,the capacity presented a high value of1255.4 mAh/g at 0.1 C,and retained at 1213.4 mAh/g after 60 cycles.Even at high rate of 5 C,the capacity still exhibited as high as 319 mAh/g.The results indicated that the synthesized N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers exhibited high cycling and rate performance.展开更多
In order to obtain a new precursor for LiFePO4,Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere.Using the as-prepared F...In order to obtain a new precursor for LiFePO4,Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere.Using the as-prepared Fe2P2O7,Li2CO3 and glucose as raw materials,pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃in an argon atmosphere.X-ray diffractometry and scanning electron microscopy(SEM)were employed to characterize the as-prepared Fe2P2O7,LiFePO4 and LiFePO4/C.The as-prepared Fe2P2O7 crystallizes in the C 1space group and belongs toβ-Fe2P2O7 for crystal phase.The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0μm.During the Li +ion chemical intercalation,radical4-2 7P Ois disrupted into two3-4 PO ions in the presence of O 2-,thus providing a feasible technique to dispose this poor dissolvable pyrophosphate.LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA.h/g,respectively.展开更多
A new lithium ion battery cathode material, composite oxide LiNi y Co z Mn 1- y-z O 2, was synthesized. The structure and physical properties of the material, including composition, distribution of size, density and s...A new lithium ion battery cathode material, composite oxide LiNi y Co z Mn 1- y-z O 2, was synthesized. The structure and physical properties of the material, including composition, distribution of size, density and specific surface area, were discussed. The characteristic of charge and discharge, reversible specific capacity and cycle property were also studied. The relationship between the structure and properties of the composite oxides was explored. The results show that the composite oxide with a reasonable composition is beneficial to the improvement and enhancement of the properties.展开更多
基金supported by the Science Foundation of the National Key Laboratory of Science and Technology on Advanced Composites in Special Environmentsthe National Natural Science Foundation of China(12002109)+1 种基金the China Postdoctoral Science Foundation(2020M670898)the Heilongjiang Postdoctoral Fund(LBH-Z20060)。
文摘Separators have been gaining increasing attention to improve the performance of lithium ion batteries(LIBs),especially for high safe and long cycle life.However,commercial polyolefin separators still face the problems of rapid capacity decay and safety issues due to the poor wettability with electrolytes and low thermal stability.Herein,a novel composite separator is proposed by introducing a surfactant of sodium dodecyl thiosulfate(SDS)into the polytetrafluoroethylene(PTFE)substrate with the binder of polyacrylic acid(PAA)through the suction filtration method.The introduction of PAA/SDS enhances the adsorption energy between PTFE substrate and electrolyte through density functional theory calculations,which improves wettability and electrolyte uptake of the separator significantly.The asachieved composite separator enables the LIBs to own high Li^(+)conductivity(0.64×10^(-3)S cm^(-1))and Li^(+)transference number(0.63),further leading to a high capacity retention of 93.50%after 500 cycles at 1 C.In addition,the uniform and smooth surface morphology of Li metal employed the composite separator after cycling indicates that the lithium dendrites can be successfully inhibited.This work indicates a promising route for the preparation of a novel composite separator for high safe LIBs.
基金supported by the Scientific and Technological Development Project of the Beijing Education Committee(No.KZ201710005009)
文摘The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate frameworks-8(ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances.In this work, the carbonized ZIF-8(C_(ZIF-8)) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/C_(ZIF-8) sample. The N_2 adsorption and desorptionisotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/C_(ZIF-8) cathode-active material delivers a discharge specific capacity of 159.3 m Ah g^(-1) at 0.1 C and a discharge specific energy of 141.7 m Wh g^(-1) after 200 cycles at 5.0 C(the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity,the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/C_(ZIF-8) cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.
基金Rachadapisek Sompoch project,Chulalongkorn University(CU_GR_62_14_62_02)the Energy Conservation and Promotion Fund Office,Ministry of Energy+2 种基金the NSFC(grant 51421091)National Science Foundation for Distinguished Young Scholars for Hebei Province of China(grant E2016203376)Asahi Glass Foundation。
文摘Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene(Ni Co-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 ? can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and Ni Co-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected,the discharge capacity of 562 m Ah g-1 at 5.0 A g-1 for 800 cycles without degradation can be achieved,rate capability and cycle performance are better than that of NiCo-LDH(~100 mAh g-1). Furthermore, the density function theory(DFT) calculations were performed to demonstrate that Ni Co-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.
基金supported by the National Natural Science Foundation of China(21776309,22122807 and 21706283)。
文摘The rate performance and cycle stability of graphitized needle coke(GNC)as anode are still limited by the sluggish kinetics and volume expansion during the Li ions intercalation and de-intercalation process.Especially,the output of energy density for lithium ion batteries(LIBs)is directly affected by the delithiation capacity below 0.5 V.Here,the mildly expanded graphitized needle coke(MEGNC)with the enlarged interlayer spacing from 0.346 to 0.352 nm is obtained by the two-step mild oxidation intercalation modification.The voltage plateau of MEGNC anode below 0.5 V is obviously broadened as compared to the initial GNC anode,contributing to the enhancement of Li storage below the low voltage plateau.Moreover,the coin full cell and pouch full cell configured with MEGNC anode exhibit much enhanced Li storage ability,energy density and better cycling stability than those full cells configured with GNC and commercial graphite anodes,demonstrating the practical application value of MEGNC.The superior anode behaviors of MEGNC including the increased effective capacity at low voltage and superior cyclic stability are mainly benefited from the enlarged interlayer spacing,which not only accelerates the Li ions diffusion rate,but also effectively alleviates the volume expansion and fragmentation during the Li ions intercalation process.In addition,the above result is further confirmed by the density functional theory simulation.This work provides an effective modification strategy for the NC-based graphite to enhance the delithiation capacity at a low voltage plateau,dedicated to improving the energy density and durability of LIBs.
基金financially supported by NSFC (Grant Nos.21621091,21373008)the National Key Research and Development Program of China (2016YFB0100202)
文摘Porous core–shell CoMn_2O_4 microspheres of ca. 3–5 μm in diameter were synthesized and served as anode of lithium ion battery. Results demonstrate that the as-synthesized CoMn_2O_4 materials exhibit excellent electrochemical properties. The CoMn_2O_4 anode can deliver a large capacity of 1070 mAh g^(–1) in the first discharge, a reversible capacity of 500 mAh g^(–1) after 100 cycles with a coulombic efficiency of 98.5%at a charge–discharge current density of 200 mA g^(–1), and a specific capacity of 385 mAh g^(–1) at a much higher charge-discharge current density of 1600 mA g^(–1). Synchrotron X–ray absorption fine structure(XAFS) techniques were applied to investigate the conversion reaction mechanism of the CoMn_2O_4 anode.The X–ray absorption near edge structure(XANES) spectra revealed that, in the first discharge–charge cycle, Co and Mn in CoMn_2O_4 were reduced to metallic Co and Mn when the electrode was discharged to 0.01 V, while they were oxidized respectively to CoO and MnO when the electrode was charged to 3.0 V.Experiments of both XANES and extended X–ray absorption fine structure(EXAFS) revealed that neither valence evolution nor phase transition of the porous core–shell CoMn_2O_4 microspheres could happen in the discharge plateau from 0.8 to 0.6 V, which demonstrates the formation of solid electrolyte interface(SEI) on the anode.
文摘Binary carbon mixtures, carbon black ECP 600JD(ECP) combined with vapor grown carbon fiber(VGCF) or carbon nanotube(CNT), or graphene(Gr) in different mass ratios, are investigated as the conductive additives for the cathode material polyoxomolybadate Na_3[AlMo_6O_(24)H_6](NAM). Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy show that the surfaces of NAM particles are covered homogeneously with the binary conductive additive mixtures except the combination of ECP and CNT. The optimum combination is the mixture of ECP and VGCF, which shows higher discharge capacity than the combinations of ECP and CNT or Gr. Initial discharge capacities of 364, 339, and 291 m A·h/g are obtained by the combination of ECP and VGCF in the mass ratios of 2:1, 1:1, and 1:2, respectively. The results of electrochemical impedance spectra and 4-pin probe measurements demonstrate that the combination of ECP and VGCF exhibits the highest electrical conductivity for the electrode.
文摘In this study, novel Carbon aerogel (CA)/Co<sub>3</sub>O<sub>4</sub>/Carbon (C) composites with a double protective structure are synthesized through a solvothermal method and in-situ polymerization. The morphology and structure are characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR). The loading content of active anode material <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> in the composite is investigated by thermogravimetry, and the electrochemical properties of the composite are characterized by electrochemical impedance spectroscopy (EIS). The SEM results show that the nano-sized spherical <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> particle is adhered to the inner Carbon aerogel (CA). The HRTEM result indicates the thickness of the prepared Carbon (C) up to 40 nm. Nano-sheet is coated on the surface of the <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> particle. Compared with the pure <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> anode materials, the Carbon aerogel (CA)/<span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub>/Carbon (C) composites have better transport kinetics for both electron and lithium-ion in EIS testing results, which may contribute to its higher specific capacity and higher first coulomb efficiency. Due to the unique structure of the composite material with double protection against the volume expansion of <span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub> when charged, the Carbon aerogel (CA)/<span style="white-space:normal;">Co</span><sub style="white-space:normal;">3</sub><span style="white-space:normal;">O</span><sub style="white-space:normal;">4</sub>/Carbon (C) composite material exhibits better cycle stability with a discharge capacity of 1180 mAh/g after 50 cycles. Therefore, the double protection strategy is verified as an effective method to improve the electrochemical performance of transition metal oxide with carbon composite as an anode material in lithium battery.
文摘Coating slurries for making anodes and cathodes of lithium batteries contain a large percentage of solid particles of different chemicals, sizes and shapes in highly viscous media. A thorough mixing of these slurries poses a major challenge in the battery manufacturing process. Several types of mixing devices and mixing methods were examined. The conventional turbine stirrers or ball mill mixers could be adequately used for the preparation of anode slurries, but not suitable for cathode slurries. In this study, a newly three-dimensional mixer, in conjunction with a multi-stage mixing sequence was proposed. The mixing effectiveness was examined by means of rheological measurements and flow visualization techniques. Preliminary electrical performance results indicated that the battery obtained using the 3D mixing device with a multi-stage mixing sequence was more efficient to those obtained from conventional methods.
文摘Anode material for lithium ion battery is prepared by chemical oxidation of natural graphite. After oxidation. the propel-ties of natural graphite are modified, such as surface structure. the content of graphite phases, the number of micropores and its stability. thus the modified natural graphite can be used as anode material for commercial lithium ion battery. The reversible capacity is increased from 100 mAh/g to above 300 mAh/g, and its cycling property is also satisfactory.
文摘W-doped Li4Ti5O12 in the form of Li4Ti4.95W0.05O12 was firstly synthesized via solid state reaction. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize the structure and morphology of Li4Ti4.95W0.05O12 . W-doping does not change the phase composition and particle morphology, while remarkably improves its cycling stability at high charge/discharge rate. Li4Ti4.95W0.05O12 exhibits an excellent rate capability with a reversible capacity of 131.2 mA·h/g at 10C and even 118.6 mA·h/g at 20C. The substitution of W for Ti site can enhance the electronic conductivity of Li4Ti5O12 via the generation of mixing Ti4+/Ti3+ , which indicates that Li4Ti4.95W0.05O12 is promising as a high rate anode for the lithium-ion batteries.
基金Funded by the Natural Science Fundation of Youth Fund in Hebei Province Universities in 2011(No:2011211)
文摘In order to improve the electrochemical performance and thermal stability of Li_(1.05)Co_(1/3)Ni_(1/3)Mn_(1/3)O_2 materials,Li_(1.05)Co_(0.3)Ni_(0.35)Mn_(0.3)M_(0.05)O_2(M=Ge,Sn)cathode materials were synthesized via co-precipitation method.The structure,electrochemical performance and thermal stability were characterized by X-ray diffraction(XRD),charge/discharge cycling,cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential scanning calorimetry(DSC).ESEM showed that Sn-doped and Ge-doped slightly increased the size of grains.XRD and CV showed that Sn-doped and Ge-doped powders were homogeneous and had the better layered structure than the bare one.Sn-doped and Ge-doped improved high rate discharge capacity and cycle-life performance.The reason of the better cycling performance of the doped one was the increasing of lithium-ion diffusion rate and charge transfer rate.Sn-doped and Ge-doped also improved the mateials thermal stability.
基金supported by Nano Special Plan from Shanghai Municipal Science and Technology Plan of Commission(No.l052nm06900)
文摘Mb2O5 -carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source,and studied as an anode material for high-performance lithium ion battery.The structural characterizations reveal that the nanocomposite possesses a core-shell structure with a thin layer of carbon shell homogeneously coated on the Nb2O5 nanocrystals.Such a unique structure enables the composite electrode with a long cycle life by preventing the Nb2O5 from volume change and pulverization during the charge-discharge process. In addition,the carbon shell efficiently improves the rate capability.Even at a current density of 500 mA·g-1,the composite electrode still exhibits a specific capacity of～100 mAh·g-1.These results suggest the possibility to utilize the Nb2O5-carbon core-shell composite as a high performance anode material in the practical application of lithium ion battery.
基金supported by the National Natural Science Foundation of China (Grant No 50771046)the Key Program of Natural Science Foundation of Guangdong Province of China (Grant No 05200534)+1 种基金the Program for Tackling Key Problems of Guangdong Province of China (Grant No 2006A10704003)the Program for Tackling Key Problems of Guangzhou City of China (GrantNo 2006Z3-D2031)
文摘This paper investigates the mechanism of Li insertion into interphase Ni3Sn in Ni-Sn alloy for the anode of lithium ion battery by means of the first-principles plane-wave pseudopotential.Compared with other phases,it is found that the Ni3Sn has larger relative expansion ratio and lower electrochemical potential,with its specific plateaus voltage around 0.3 eV when lithium atoms are filled in all octahedral interstitial sites,and the relative expansion ratio increasing dramatically when the lithiated phase transits from octahedral interstitial sites to tetrahedral interstitial sites.So this phase is a devastating phase for whole alloy electrode materials.
基金supported by 973(2011CB935900,2010CB631303)NSFC(21231005,51071087)+4 种基金111 Project(B12015)MOE(IRT13R30)the Research Fund for the Doctoral Program of Higher Education of China(20120031110001)Tianjin Sci&Tech Project(10SYSYJC27600)the Nature Science Foundation of Tianjin(11JCYBJC07700)
文摘Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn_(0.6)Fe_(0.4)PO_4(S2)was about 80 nm in diameter.The discharge capacity of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn_(0.6)Fe_(0.4)PO_4 and it in situ reduction of GO could improve the electrical conductivity of LiMn_(0.6)Fe_(0.4)PO_4 material.
基金Projects(50771046 20373016) supported by the National Natural Science Foundation of China+2 种基金Project(05200534) supported by the Natural Science Foundation of Guangdong Province, ChinaProject(2006A10704003) supported by the Key Project of Guangdong Province, ChinaProject(2006Z3-D2031) supported by the Key Project of Guangzhou City, China
文摘Sn thin film on Cu foil substrate as the anode of lithium ion battery was prepared by direct current magnetron sputtering(DCMS). The surface morphology,composition and thickness and the electrochemical behaviors of the prepared Sn thin film were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),inductively coupled plasma atomic emission spectrometry(ICP),cyclic voltammetry(CV) and galvanostatic charge/ discharge(GC) measurements. It is found that the Sn film is consists of pure Sn with an average particle diameter of 100 nm. The thickness of the film is about 320 nm. The initial lithium insertion capacity of the Sn film is 771 mA·h/g. The reversible capacity of the film is 570 mA·h/g and kept at 270 mA·h/g after 20 cycles.
基金supported by the Natural Science Foundation of Guangdong Province (Grant No.2017B030306013)the key project of Science and Technology in Guangdong Province (Grant No.2017A010106006)
文摘A novel bismuth–carbon composite, in which bismuth nanoparticles were anchored in a nitrogen-doped carbon matrix(Bi@NC), is proposed as anode for high volumetric energy density lithium ion batteries(LIBs).Bi@NC composite was synthesized via carbonization of Zn-containing zeolitic imidazolate(ZIF-8) and replacement of Zn with Bi, resulting in the N-doped carbon that was hierarchically porous and anchored with Bi nanoparticles. The matrix provides a highly electronic conductive network that facilitates the lithiation/delithiation of Bi.Additionally, it restrains aggregation of Bi nanoparticles and serves as a buffer layer to alleviate the mechanical strain of Bi nanoparticles upon Li insertion/extraction.With these contributions, Bi@NC exhibits excellent cycling stability and rate capacity compared to bare Bi nanoparticles or their simple composites with carbon. This study provides a new approach for fabricating high volumetric energy density LIBs.
基金the National Natural Science Foundation of China (No. 91634108, 21376148 and 61503246)National Key Program(2017FYA0205300)
文摘N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers have been successfully synthesized according to a facile solvothermal/hydrothermal method.The obtained CNTs@α-Fe_2O_3@C nanofibers composites exhibited special three-dimensional(3-D)network structure,which endows they promising candidate for anode materials of lithium ion battery.The coaxial property of CNTs@α-Fe_2O_3@C nanofibers could significantly improve the cycling and rate performance owing to the acceleration of charge/electron transfer,improvement of conductivity,maintaining of structural integrity and inhibiting the aggregation.Theα-Fe_2O_3nanoparticles with small size and high percentage of N-doped amount could further improve the electrochemical performance.As for the CNT@α-Fe_2O_3@C nanofibers,the capacity presented a high value of1255.4 mAh/g at 0.1 C,and retained at 1213.4 mAh/g after 60 cycles.Even at high rate of 5 C,the capacity still exhibited as high as 319 mAh/g.The results indicated that the synthesized N-doped coaxial CNTs@α-Fe_2O_3@C nanofibers exhibited high cycling and rate performance.
基金Project(50604018)supported by the National Natural Science Foundation of China
文摘In order to obtain a new precursor for LiFePO4,Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere.Using the as-prepared Fe2P2O7,Li2CO3 and glucose as raw materials,pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃in an argon atmosphere.X-ray diffractometry and scanning electron microscopy(SEM)were employed to characterize the as-prepared Fe2P2O7,LiFePO4 and LiFePO4/C.The as-prepared Fe2P2O7 crystallizes in the C 1space group and belongs toβ-Fe2P2O7 for crystal phase.The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0μm.During the Li +ion chemical intercalation,radical4-2 7P Ois disrupted into two3-4 PO ions in the presence of O 2-,thus providing a feasible technique to dispose this poor dissolvable pyrophosphate.LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA.h/g,respectively.
文摘A new lithium ion battery cathode material, composite oxide LiNi y Co z Mn 1- y-z O 2, was synthesized. The structure and physical properties of the material, including composition, distribution of size, density and specific surface area, were discussed. The characteristic of charge and discharge, reversible specific capacity and cycle property were also studied. The relationship between the structure and properties of the composite oxides was explored. The results show that the composite oxide with a reasonable composition is beneficial to the improvement and enhancement of the properties.
