The concentration difference in the near-surface region of lithium metal is the main cause of lithium dendrite growth.Resolving this issue will be key to achieving high-performance lithium metal batteries(LMBs).Herein...The concentration difference in the near-surface region of lithium metal is the main cause of lithium dendrite growth.Resolving this issue will be key to achieving high-performance lithium metal batteries(LMBs).Herein,we construct a lithium nitrate(LiNO_(3))-implanted electroactiveβphase polyvinylidene fluoride-co-hexafluoropropylene(PVDF-HFP)crystalline polymorph layer(PHL).The electronegatively charged polymer chains attain lithium ions on the surface to form lithium-ion charged channels.These channels act as reservoirs to sustainably release Li ions to recompense the ionic flux of electrolytes,decreasing the growth of lithium dendrites.The stretched molecular channels can also accelerate the transport of Li ions.The combined effects enable a high Coulombic efficiency of 97.0%for 250 cycles in lithium(Li)||copper(Cu)cell and a stable symmetric plating/stripping behavior over 2000 h at 3 mA cm^(-2)with ultrahigh Li utilization of 50%.Furthermore,the full cell coupled with PHL-Cu@Li anode and Li Fe PO_(4) cathode exhibits long-term cycle stability with high-capacity retention of 95.9%after 900 cycles.Impressively,the full cell paired with LiNi_(0.87)Co_(0.1)Mn_(0.03)O_(2)maintains a discharge capacity of 170.0 mAh g^(-1)with a capacity retention of 84.3%after 100 cycles even under harsh condition of ultralow N/P ratio of 0.83.This facile strategy will widen the potential application of LiNO_(3)in ester-based electrolyte for practical high-voltage LMBs.展开更多
The efficient synthesis of ultrathin crystalline twodimensional(2D)polymers with well-defined repeating units is essential to realize their broad applications but remains a great challenge.Herein,we report a new strat...The efficient synthesis of ultrathin crystalline twodimensional(2D)polymers with well-defined repeating units is essential to realize their broad applications but remains a great challenge.Herein,we report a new strategy to directly synthesize a series of few-layer 2D triazine-based polymers(2DTPs)via trimerization reaction of aromatic aldoximes in one step with a high yield of 85%using AlCl3 as catalyst under solvent-free conditions.The obtained 2D-TPs show high crystallinity,a lateral size of several micrometers,an ultrathin thickness less than 2 nm,and good dispersibility and processability.Through semi-in situ and detailed control experiments,we reveal that the 2D polymerization reaction is a two-step process of dehydration and then cyclotrimerization,and AlCl3 acts as not only catalyst but also an in situ generated template for promoting the formation of 2D-TPs.When explored as a new polymeric anode for potassium-ion batteries,the 2D-TP displayed an extraordinary reversible specific capacity of 356 mAh g^(−1)at 0.05 A g^(−1),which is among the best performances ever reported,outstanding rate capability(153 mAh g^(−1)at 1 A g^(−1)),and excellent cycling stability with 95.1%capacity retention after 1000 cycles at 1 A g^(−1).展开更多
Unexpected intercalation-dominated process is observed duri ng K^+insertion in WS2 in a voltage range of 0.01-3.0 V.This is different fromthe previously reported two-dimensional(2D)transition metal dichalcogenides tha...Unexpected intercalation-dominated process is observed duri ng K^+insertion in WS2 in a voltage range of 0.01-3.0 V.This is different fromthe previously reported two-dimensional(2D)transition metal dichalcogenides that undergo a conversion reaction in a low voltage rangewhen used as anodes in potassium-ion batteries.Charge/discharge processes in the K and Na cells are studied in parallel to demonstrate thedifferention storage mechanisms.The Na^+storage proceeds through intercalation and conversion reactions while the K^+storage is governedby an intercalation reaction.Owing to the reversible K^+intercalation in the van der Waals gaps,the WS2 anode exhibits a low decay rate of 0.07%per cycle,delivering a capacity of 103 mAh·g^-1 after 100 cycles at 100 mA·g^-1.It maintains 57%capacity at 800 mA·g^-1 and shows stablecyclability up to 400 cycles at 500 mA·g^-1.Kinetics study proves the facilitation of K^+transport is derived from the intercalation-dominatedmecha nism.Furthermore,the mechanismis verified by the density functional theory(DFT)calculations,showing that the progressive expansion of the interlayer space can account for the observed results.展开更多
基金the financial support from the National Natural Science Foundation of China(Nos.22205191 and 52002346)the Science and Technology Innovation Program of Hunan Province(No.2021RC3109)+1 种基金the Natural Science Foundation of Hunan Province,China(No.2022JJ40446)Guangxi Key Laboratory of Low Carbon Energy Material(No.2020GXKLLCEM01)。
文摘The concentration difference in the near-surface region of lithium metal is the main cause of lithium dendrite growth.Resolving this issue will be key to achieving high-performance lithium metal batteries(LMBs).Herein,we construct a lithium nitrate(LiNO_(3))-implanted electroactiveβphase polyvinylidene fluoride-co-hexafluoropropylene(PVDF-HFP)crystalline polymorph layer(PHL).The electronegatively charged polymer chains attain lithium ions on the surface to form lithium-ion charged channels.These channels act as reservoirs to sustainably release Li ions to recompense the ionic flux of electrolytes,decreasing the growth of lithium dendrites.The stretched molecular channels can also accelerate the transport of Li ions.The combined effects enable a high Coulombic efficiency of 97.0%for 250 cycles in lithium(Li)||copper(Cu)cell and a stable symmetric plating/stripping behavior over 2000 h at 3 mA cm^(-2)with ultrahigh Li utilization of 50%.Furthermore,the full cell coupled with PHL-Cu@Li anode and Li Fe PO_(4) cathode exhibits long-term cycle stability with high-capacity retention of 95.9%after 900 cycles.Impressively,the full cell paired with LiNi_(0.87)Co_(0.1)Mn_(0.03)O_(2)maintains a discharge capacity of 170.0 mAh g^(-1)with a capacity retention of 84.3%after 100 cycles even under harsh condition of ultralow N/P ratio of 0.83.This facile strategy will widen the potential application of LiNO_(3)in ester-based electrolyte for practical high-voltage LMBs.
基金support by the National Natural Science Foundation of China(grant nos.22022510 and 51873039)the Science and Technology Innovation Program of Hunan Province(grant no.2021RC2086).
文摘The efficient synthesis of ultrathin crystalline twodimensional(2D)polymers with well-defined repeating units is essential to realize their broad applications but remains a great challenge.Herein,we report a new strategy to directly synthesize a series of few-layer 2D triazine-based polymers(2DTPs)via trimerization reaction of aromatic aldoximes in one step with a high yield of 85%using AlCl3 as catalyst under solvent-free conditions.The obtained 2D-TPs show high crystallinity,a lateral size of several micrometers,an ultrathin thickness less than 2 nm,and good dispersibility and processability.Through semi-in situ and detailed control experiments,we reveal that the 2D polymerization reaction is a two-step process of dehydration and then cyclotrimerization,and AlCl3 acts as not only catalyst but also an in situ generated template for promoting the formation of 2D-TPs.When explored as a new polymeric anode for potassium-ion batteries,the 2D-TP displayed an extraordinary reversible specific capacity of 356 mAh g^(−1)at 0.05 A g^(−1),which is among the best performances ever reported,outstanding rate capability(153 mAh g^(−1)at 1 A g^(−1)),and excellent cycling stability with 95.1%capacity retention after 1000 cycles at 1 A g^(−1).
文摘Unexpected intercalation-dominated process is observed duri ng K^+insertion in WS2 in a voltage range of 0.01-3.0 V.This is different fromthe previously reported two-dimensional(2D)transition metal dichalcogenides that undergo a conversion reaction in a low voltage rangewhen used as anodes in potassium-ion batteries.Charge/discharge processes in the K and Na cells are studied in parallel to demonstrate thedifferention storage mechanisms.The Na^+storage proceeds through intercalation and conversion reactions while the K^+storage is governedby an intercalation reaction.Owing to the reversible K^+intercalation in the van der Waals gaps,the WS2 anode exhibits a low decay rate of 0.07%per cycle,delivering a capacity of 103 mAh·g^-1 after 100 cycles at 100 mA·g^-1.It maintains 57%capacity at 800 mA·g^-1 and shows stablecyclability up to 400 cycles at 500 mA·g^-1.Kinetics study proves the facilitation of K^+transport is derived from the intercalation-dominatedmecha nism.Furthermore,the mechanismis verified by the density functional theory(DFT)calculations,showing that the progressive expansion of the interlayer space can account for the observed results.
