Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_...Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.展开更多
The Nickel-rich layered cathode materials charged to 4.5 V can obtain a specific capacity of more than 200 m Ah g^(-1).However,the nickel-rich layered cathode materials suffer from the severe capacity fade during high...The Nickel-rich layered cathode materials charged to 4.5 V can obtain a specific capacity of more than 200 m Ah g^(-1).However,the nickel-rich layered cathode materials suffer from the severe capacity fade during high-voltage cycling,which is related to the phase transformation and the surface sides reactions caused by the lattice oxygen evolution.Here,the simultaneous construction of a Mg,Ti-based surface integrated layer and bulk doping through Mg,Ti surface treatment could suppress the lattice oxygen evolution of Nirich material at deep charging.More importantly,Mg and Ti are co-doped into the particles surface to form an Mg_(2)TiO_(4) and Mg_(0.5–x)Ti_(2–y)(PO_(4))_(3) outer layer with Mg and Ti vacancies.In the constructed surface integrated layer,the reverse electric field in the Mg_(2)TiO_(4) effectively suppressed the outward migration of the lattice oxygen anions,while Mg_(0.5–x)Ti_(2–y)(PO_(4))_(3) outer layer with high electronic conductivity and good lithium ion conductor could effectively maintained the stability of the reaction interface during highvoltage cycling.Meanwhile,bulk Mg and Ti co-doping can mitigate the migration of Ni ions in the bulk to keep the stability of transition metal–oxygen(M-O)bond at deep charging.As a result,the NCM@MTP cathode shows excellent long cycle stability at high-voltage charging,which keep high capacity retention of 89.3%and 84.3%at 1 C after 200 and 100 cycles under room and elevated temperature of 25 and 55°C,respectively.This work provides new insights for manipulating the surface chemistry of electrode materials to suppress the lattice oxygen evolution at high charging voltage.展开更多
Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical ...Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical performance,which seriously limits the practical application in lithium-ion batteries.Herein,NiSb nanoparticles encapsulated by carbon nanosheets have been developed via a facile strategy and as anode for lithium-ion batteries.In this attractive structure,the carbon nanosheets can effectively avoid volume change of NiSb nanoparticles and inhibit the direct contact of NiSb nanoparticles to the electrolyte during the lithiation/delithiation process.As a result,the NiSb/C nanosheets display an outstanding long cycling performance(405 mA h g-1 after 1000 cycles at 1.0 A g-1) and excellent rate capability(305 mA h g-1 at 2.0 A g-1) when application in lithium-ion batteries.展开更多
The Nickel-rich layered cathode materials have been considered as promising cathode for lithium-ion batteries(LIBs),which due to it can achieve a high capacity of than 200 mAh g^(-1)under a high cutoff voltage of4.5 V...The Nickel-rich layered cathode materials have been considered as promising cathode for lithium-ion batteries(LIBs),which due to it can achieve a high capacity of than 200 mAh g^(-1)under a high cutoff voltage of4.5 V.However,the nickel-rich layered cathode materials show severely capacity fading at high voltage cycling,induced by the hybrid O anion and cation redox promote O^(α-)(α<2)migration in the crystal lattice under high charge voltage,lead to the instability of the oxygen skeleton and oxygen evolution,promote the phase transition and electrolyte decomposition.Here,Li_(1-x)TMO_(2-y)/Li_(2)SO_(4) hybrid layer is designed by a simple pyrolysis method to enhance the high voltage cycle stability of NCM.In such constructed hybrid layer,the inner spinel structure of Li_(1-x)TMO_(2-y)layer is the electron-rich state,which could form an electron cloud coupling with the NCM with surface oxygen vacancies,while Li_(2)SO_(4) is p-type semiconductors,thus constructing a heterojunction interface of Li_(1-x)TMO_(2-y)//Li_(2)SO_(4) and Li_(1-x)TMO_(2-y)//NCM,thereby generating internal self-built electric fields to inhibit the outward migration of bulk oxygen anions.Moreover,the internal self-built electric fields could not only strengthen the bonding force between the Li_(1-x)TMO_(2-y)/Li_(2)SO_(4) hybrid layer and host NCM material,but also boost the charge transfer.As consequence,the modified NCM materials show excellent electrochemical performance with capacity retention of 97.7%and 90.1%after 200 cycles at 4.3 V and 4.5 V,respectively.This work provides a new idea for the development of high energy density applications of Nickel-rich layered cathode materials.展开更多
基金supported by the Special Project for the Central Government to Guide Local Technological Development (GUIKE ZY20198008)the Guangxi Technology Base and talent Subject (GUIKE AD20238012,AD20297086)+5 种基金the Natural Science Foundation of Guangxi Province (2021GXNSFDA075012)the National Natural Science Foundation of China (51902108,52104298,22169004)the National Natural Science Foundation of China (U20A20249)the Regional Innovation and Development Joint Fundthe Guangxi Innovation Driven Development Subject (GUIKE AA19182020,19254004)the Special Fund for Guangxi Distinguished Expert。
文摘Charging P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)to 4.5 V for higher capacity is enticing.However,it leads to severe capacity fading,ascribing to the lattice oxygen evolution and the P2-O2 phase transformation.Here,the Mg Fe_(2)O_(4) coating and Mg,Fe co-doping were constructed simultaneously by Mg,Fe surface treatment to suppress lattice oxygen evolution and P2-O2 phase transformation of P2-Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)at deep charging.Through ex-situ X-ray diffraction(XRD)tests,we found that the Mg,Fe bulk co-doping could reduce the repulsion between transition metals and Na+/vacancies ordering,thus inhibiting the P2-O2 phase transition and significantly reducing the irreversible volume change of the material.Meanwhile,the internal electric field formed by the dielectric polarization of Mg Fe_(2)O_(4) effectively inhibits the outward migration of oxidized O^(a-)(a<2),thereby suppressing the lattice oxygen evolution at deep charging,confirmed by in situ Raman and ex situ XPS techniques.P2-Na NM@MF-3 shows enhanced high-voltage cycling performance with capacity retentions of 84.8% and 81.3%at 0.1 and 1 C after cycles.This work sheds light on regulating the surface chemistry for Na-layered oxide materials to enhance the high-voltage performance of Na-ion batteries.
基金supported by the National Natural Science Foundation of China(51902108,51762006,51964013)the Special Projects for Central Government to Guide Local Technological Development(GUIKE ZY20198008)+2 种基金the Guangxi InnovationDriven Development Subject(GUIKE AA19182020,GUIKE AA19254004)the Guangxi Technology Base and Talent Subject(GUIKE AD18126001,GUIKE AD20999012,GUIKE AD20297086)the Special Fund for Guangxi Distinguished Expert。
文摘The Nickel-rich layered cathode materials charged to 4.5 V can obtain a specific capacity of more than 200 m Ah g^(-1).However,the nickel-rich layered cathode materials suffer from the severe capacity fade during high-voltage cycling,which is related to the phase transformation and the surface sides reactions caused by the lattice oxygen evolution.Here,the simultaneous construction of a Mg,Ti-based surface integrated layer and bulk doping through Mg,Ti surface treatment could suppress the lattice oxygen evolution of Nirich material at deep charging.More importantly,Mg and Ti are co-doped into the particles surface to form an Mg_(2)TiO_(4) and Mg_(0.5–x)Ti_(2–y)(PO_(4))_(3) outer layer with Mg and Ti vacancies.In the constructed surface integrated layer,the reverse electric field in the Mg_(2)TiO_(4) effectively suppressed the outward migration of the lattice oxygen anions,while Mg_(0.5–x)Ti_(2–y)(PO_(4))_(3) outer layer with high electronic conductivity and good lithium ion conductor could effectively maintained the stability of the reaction interface during highvoltage cycling.Meanwhile,bulk Mg and Ti co-doping can mitigate the migration of Ni ions in the bulk to keep the stability of transition metal–oxygen(M-O)bond at deep charging.As a result,the NCM@MTP cathode shows excellent long cycle stability at high-voltage charging,which keep high capacity retention of 89.3%and 84.3%at 1 C after 200 and 100 cycles under room and elevated temperature of 25 and 55°C,respectively.This work provides new insights for manipulating the surface chemistry of electrode materials to suppress the lattice oxygen evolution at high charging voltage.
基金the financial support from Guangdong Natural Science Funds for Distinguished Young Scholar(2016A030306010)China Postdoctoral Science Foundation(2017M622675)Natural Science Foundation of Guangdong Province(2018A030313944)
文摘Metallic antimony(Sb) has been attracted much attentions as anode for lithium-ion batteries due to its high capacity.Nevertheless,the large volume expansion during the lithiation process leads to poor electrochemical performance,which seriously limits the practical application in lithium-ion batteries.Herein,NiSb nanoparticles encapsulated by carbon nanosheets have been developed via a facile strategy and as anode for lithium-ion batteries.In this attractive structure,the carbon nanosheets can effectively avoid volume change of NiSb nanoparticles and inhibit the direct contact of NiSb nanoparticles to the electrolyte during the lithiation/delithiation process.As a result,the NiSb/C nanosheets display an outstanding long cycling performance(405 mA h g-1 after 1000 cycles at 1.0 A g-1) and excellent rate capability(305 mA h g-1 at 2.0 A g-1) when application in lithium-ion batteries.
基金supported by the National Natural Science Foundation of China(51902108,51762006,51964013)the Special Projects for Central Government to Guide Local Technological Development(GUIKE ZY20198008)+2 种基金the Guangxi InnovationDriven Development Subject(GUIKE AA19182020,GUIKE AA19254004)the Guangxi Technology Base and Talent Subject(GUIKE AD18126001,GUIKE AD20999012,GUIKE AD20297086)the Special Fund for Guangxi Distinguished Expert。
文摘The Nickel-rich layered cathode materials have been considered as promising cathode for lithium-ion batteries(LIBs),which due to it can achieve a high capacity of than 200 mAh g^(-1)under a high cutoff voltage of4.5 V.However,the nickel-rich layered cathode materials show severely capacity fading at high voltage cycling,induced by the hybrid O anion and cation redox promote O^(α-)(α<2)migration in the crystal lattice under high charge voltage,lead to the instability of the oxygen skeleton and oxygen evolution,promote the phase transition and electrolyte decomposition.Here,Li_(1-x)TMO_(2-y)/Li_(2)SO_(4) hybrid layer is designed by a simple pyrolysis method to enhance the high voltage cycle stability of NCM.In such constructed hybrid layer,the inner spinel structure of Li_(1-x)TMO_(2-y)layer is the electron-rich state,which could form an electron cloud coupling with the NCM with surface oxygen vacancies,while Li_(2)SO_(4) is p-type semiconductors,thus constructing a heterojunction interface of Li_(1-x)TMO_(2-y)//Li_(2)SO_(4) and Li_(1-x)TMO_(2-y)//NCM,thereby generating internal self-built electric fields to inhibit the outward migration of bulk oxygen anions.Moreover,the internal self-built electric fields could not only strengthen the bonding force between the Li_(1-x)TMO_(2-y)/Li_(2)SO_(4) hybrid layer and host NCM material,but also boost the charge transfer.As consequence,the modified NCM materials show excellent electrochemical performance with capacity retention of 97.7%and 90.1%after 200 cycles at 4.3 V and 4.5 V,respectively.This work provides a new idea for the development of high energy density applications of Nickel-rich layered cathode materials.
