The hydrolysis of MgH_(2) delivers high hydrogen capacity(15.2 wt%),which is very attractive for real-time hydrogen supply.However,the formation of a surface passivation Mg(OH)_(2) layer and the large excess of H_(2)O...The hydrolysis of MgH_(2) delivers high hydrogen capacity(15.2 wt%),which is very attractive for real-time hydrogen supply.However,the formation of a surface passivation Mg(OH)_(2) layer and the large excess of H_(2)O required to ensure complete hydrolysis are two key challenges for the MgH_(2) hydrolysis systems.Now,a low-cost method is reported to synthesize MgH_(2)@Mg(BH_(4))_(2) composite via ball-milling MgH_(2) with cheap and widely available B_(2)O_(3)(or B(OH)_(3)).By adding small amounts of B_(2)O_(3),the in-situ formed Mg(BH_(4))_(2) could significantly promote the hydrolysis of MgH_(2).In particular,the MgH_(2)–10 wt%B_(2)O_(3) composite releases 1330.7 mL·g^(−1) H_(2)(close to 80%theoretical hydrogen generation H_(2))in H_(2)O and 1520.4 mL·g^(−1) H_(2)(about 95%)in 0.5 M MgCl_(2) in 60 min at 26℃ with hydrolysis rate of 736.9 mL·g^(−1)·min^(−1) and 960.9 mL·g^(−1)·min^(−1) H_(2) during the first minute of the hydrolysis,respectively.In addition,the MgCl_(2) solution allows repeated use by filtering and exhibits high cycle stability(20 cycles),therefore leading to much reduced capacity loss caused by the excess H_(2)O.We show that by introducing B_(2)O_(3) and recycling the 0.5 M MgCl_(2) solution,the system hydrogen capacity can approach 5.9 wt%,providing a promising hydrogen generation scheme to supply hydrogen to the fuel cells.展开更多
Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivit...Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.展开更多
The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and ...The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and long-haul electric vehicles.Monoclinic TiNb_(2)O_(7)(TNO)with the theoretical capacity of 387 mAh g^(-1)has been proposed as a high-capacity anode materials to replace Li4Ti5O12.In this work,homovalent doping strategy was used to enhance the electrochemical performance of TiNb_(2)O_(7)(TNO)by employing Zr to partial substitute Ti through solvothermal method.The doping of Zr^(4+)ions can enlarge the lattice structure without changing the chemical valence of the original elements,refine and homogenize the grains,improve the electrical conductivity,and accelerate the ion diffusion kinetics,and finally enhance the cycle and rate performance.Specifically,Z0.05-TNO shows initial discharge capacity of as high as 312.2 mAh g^(-1)at 1 C and 244.8 mAh g^(-1)at 10 C,and still maintains a high specific capacity of 171.3 mAh g^(-1)after 800 cycles at 10 C.This study provides a new strategy for high-performance fast-charging energy storage electrodes.展开更多
Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.E...Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.EC is also the most widely used electrolyte solvent in sodium ion batteries.However,compared to lithium metal,sodium metal(Na)shows higher activity and reacts violently with EC-based electrolyte(NaPF_(6)as solute),which leads to the failure of sodium metal batteries(SMBs).Herein,we reveal the electrochemical instability mechanism of EC on sodium metal battery,and find that the com-bination of EC and NaPF_(6) is electrically reduced in sodium metal anode during charging,resulting in the reduction of the first coulombic efficiency,and the continuous consumption of electrolyte leads to the cell failure.To address the above issues,an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes.Specifically,ethyl methyl carbonate(EMC)and dimethyl carbon-ate(DMC)as solvents and fluoroethylene carbonate(FEC)as SEI-forming additive have been identified as the optimal solvent for NaFP_(6)based electrolyte and used in Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))/Na batteries.The batter-ies exhibit excellent capacity retention rate of about 80%over 1000 cycles at a cut-off voltage of 4.3 V.展开更多
基金supported by the Basic and Applied Basic Research Foundation of Guangdong Province(No.2022A1515011832 and 2021A1515110676)supported by GDAS’Project of Science and Technology Development(2022GDASZH-2022010104,2022GDASZH-2022030604-04).
文摘The hydrolysis of MgH_(2) delivers high hydrogen capacity(15.2 wt%),which is very attractive for real-time hydrogen supply.However,the formation of a surface passivation Mg(OH)_(2) layer and the large excess of H_(2)O required to ensure complete hydrolysis are two key challenges for the MgH_(2) hydrolysis systems.Now,a low-cost method is reported to synthesize MgH_(2)@Mg(BH_(4))_(2) composite via ball-milling MgH_(2) with cheap and widely available B_(2)O_(3)(or B(OH)_(3)).By adding small amounts of B_(2)O_(3),the in-situ formed Mg(BH_(4))_(2) could significantly promote the hydrolysis of MgH_(2).In particular,the MgH_(2)–10 wt%B_(2)O_(3) composite releases 1330.7 mL·g^(−1) H_(2)(close to 80%theoretical hydrogen generation H_(2))in H_(2)O and 1520.4 mL·g^(−1) H_(2)(about 95%)in 0.5 M MgCl_(2) in 60 min at 26℃ with hydrolysis rate of 736.9 mL·g^(−1)·min^(−1) and 960.9 mL·g^(−1)·min^(−1) H_(2) during the first minute of the hydrolysis,respectively.In addition,the MgCl_(2) solution allows repeated use by filtering and exhibits high cycle stability(20 cycles),therefore leading to much reduced capacity loss caused by the excess H_(2)O.We show that by introducing B_(2)O_(3) and recycling the 0.5 M MgCl_(2) solution,the system hydrogen capacity can approach 5.9 wt%,providing a promising hydrogen generation scheme to supply hydrogen to the fuel cells.
基金financially supported by the National Natural Science Foundation of China (Grant No.52171221)the National Key Research and Development Program of China (Grant No.2019YFA0704900)。
文摘Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.
基金supported by the National Natural Science Foundation of China(52272258)Beijing Nova Program(20220484214)+1 种基金Fundamental Research Funds for the Central Universities(No.2021JCCXJD01)Key R&D and transformation projects in Qinghai Province(2021-HZ-808)and Hebei Province(21314401D).
文摘The low energy density,unsatisfied cycling performance,potential safety issue and slow charging kinetics of the commercial lithium-ion batteries restrained their further application in the fields of fast charging and long-haul electric vehicles.Monoclinic TiNb_(2)O_(7)(TNO)with the theoretical capacity of 387 mAh g^(-1)has been proposed as a high-capacity anode materials to replace Li4Ti5O12.In this work,homovalent doping strategy was used to enhance the electrochemical performance of TiNb_(2)O_(7)(TNO)by employing Zr to partial substitute Ti through solvothermal method.The doping of Zr^(4+)ions can enlarge the lattice structure without changing the chemical valence of the original elements,refine and homogenize the grains,improve the electrical conductivity,and accelerate the ion diffusion kinetics,and finally enhance the cycle and rate performance.Specifically,Z0.05-TNO shows initial discharge capacity of as high as 312.2 mAh g^(-1)at 1 C and 244.8 mAh g^(-1)at 10 C,and still maintains a high specific capacity of 171.3 mAh g^(-1)after 800 cycles at 10 C.This study provides a new strategy for high-performance fast-charging energy storage electrodes.
基金supported by the National Natural Science Foundation of China(52172201,51732005,51902118,and 52102249)the China Postdoctoral Science Foundation(2019M662609and 2020T130217)for financial support。
文摘Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.EC is also the most widely used electrolyte solvent in sodium ion batteries.However,compared to lithium metal,sodium metal(Na)shows higher activity and reacts violently with EC-based electrolyte(NaPF_(6)as solute),which leads to the failure of sodium metal batteries(SMBs).Herein,we reveal the electrochemical instability mechanism of EC on sodium metal battery,and find that the com-bination of EC and NaPF_(6) is electrically reduced in sodium metal anode during charging,resulting in the reduction of the first coulombic efficiency,and the continuous consumption of electrolyte leads to the cell failure.To address the above issues,an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes.Specifically,ethyl methyl carbonate(EMC)and dimethyl carbon-ate(DMC)as solvents and fluoroethylene carbonate(FEC)as SEI-forming additive have been identified as the optimal solvent for NaFP_(6)based electrolyte and used in Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))/Na batteries.The batter-ies exhibit excellent capacity retention rate of about 80%over 1000 cycles at a cut-off voltage of 4.3 V.
