The potentiostatic intermittent titration technique(PITT)is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries,pred...The potentiostatic intermittent titration technique(PITT)is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries,predicated on the assumption that the insertion/extraction of ions in the host materials is governed by diffusion.However,in practical scenarios,the electrochemical process might be dominated by interfacial reaction kinetics rather than diffusion.The present work derives analytical equations for electric current by considering the finite interfacial reaction kinetics and small overpotentials during PITT measurements and further studies the chemical stress field induced by the interfacial reaction-controlled ion insertion.The exchange current density(j_(0))can be ascertained using the analytical equation,which dictates the magnitude and decay rate of the electric current during a PITT process.The electric current decays more rapidly,and consequently,the lithium concentration reaches equilibrium faster for larger values of j_(0).The magnitude of the chemical stress is independent of j_(0) but depends on the overpotential.展开更多
The exfoliation of bulk 2H-molybdenum disulfide(2H-MoS_(2))into few-layer nanosheets with 1T-phase and controlled layers represents a daunting challenge towards the device applications of MoS_(2).Conventional ion inte...The exfoliation of bulk 2H-molybdenum disulfide(2H-MoS_(2))into few-layer nanosheets with 1T-phase and controlled layers represents a daunting challenge towards the device applications of MoS_(2).Conventional ion intercalation assisted exfoliation needs the use of hazardous n-butyllithium and/or elaborate control of the intercalation potential to avoid the decomposition of the MoS_(2).This work reports a facile strategy by intercalating Li ions electrochemically with ether-based electrolyte into the van der Waals(vdW)channels of MoS_(2),which successfully avoids the decomposition of MoS_(2)at low potentials.The co-intercalation of Li+and the ether solvent into MoS_(2)makes a first-order phase transformation,forming a superlattice phase,which preserves the layered structure and hence enables the exfoliation of bulk 2H-MoS_(2)into bilayer nanosheets with 1T-phase.Compared with the pristine 2H-MoS_(2),the bilayer 1T-MoS_(2)nanosheets exhibit better electrocatalytic performance for the hydrogen evolution reaction(HER).This facile method should be easily extended to the exfoliation of various transition metal dichalcogenides(TMDs).展开更多
Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries.In this work,a homemade in situ measurement device was us...Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries.In this work,a homemade in situ measurement device was used to characterize simultaneously chemical strain and nominal state of charge,especially residual chemical strain and residual nominal state of charge,in graphite-based electrodes at various temperatures.The measurements indicate that raising the testing temperature from 20℃ to 60℃ decreases the chemical strain at the same nominal state of charge during cycling,while residual chemical strain and residual nominal state of charge increase with the increase of temperature.Furthermore,a novel electrochemicalmechanical model is developed to evaluate quantitatively the chemical strain caused by a solid electrolyte interface(SEI)and the partial molar volume of Li in the SEI at different temperatures.The present study will definitely stimulate future investigations on the electro-chemo-mechanics coupling behaviors in lithium-ion batteries.展开更多
Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries.In this work,a homemade in situ measurement device was us...Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries.In this work,a homemade in situ measurement device was used to characterize simultaneously chemical strain and nominal state of charge,especially residual chemical strain and residual nominal state of charge,in graphite-based electrodes at various temperatures.The measurements indicate that raising the testing temperature from 20℃ to 60℃ decreases the chemical strain at the same nominal state of charge during cycling,while residual chemical strain and residual nominal state of charge increase with the increase of temperature.Furthermore,a novel electrochemicalmechanical model is developed to evaluate quantitatively the chemical strain caused by a solid electrolyte interface(SEI)and the partial molar volume of Li in the SEI at different temperatures.The present study will definitely stimulate future investigations on the electro-chemo-mechanics coupling behaviors in lithium-ion batteries.展开更多
基金supported by the National Natural Science Foundation of China(No.12374003)the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515030256)the Shenzhen Science and Technology Program(Grant Nos.JCYJ20220531095208019 and GXWD20231129103124001).
文摘The potentiostatic intermittent titration technique(PITT)is widely used to determine the diffusion coefficient of ions in electrode materials for rechargeable batteries such as lithium-ion or sodium-ion batteries,predicated on the assumption that the insertion/extraction of ions in the host materials is governed by diffusion.However,in practical scenarios,the electrochemical process might be dominated by interfacial reaction kinetics rather than diffusion.The present work derives analytical equations for electric current by considering the finite interfacial reaction kinetics and small overpotentials during PITT measurements and further studies the chemical stress field induced by the interfacial reaction-controlled ion insertion.The exchange current density(j_(0))can be ascertained using the analytical equation,which dictates the magnitude and decay rate of the electric current during a PITT process.The electric current decays more rapidly,and consequently,the lithium concentration reaches equilibrium faster for larger values of j_(0).The magnitude of the chemical stress is independent of j_(0) but depends on the overpotential.
基金the National Natural Science Foundation of China(No.12374003)the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515012349)+1 种基金the Shenzhen Science and Technology Program(Nos.RCBS20200714114920129 and JCYJ20220531095208019)the Guangzhou Municipal Science and Technology Project(No.2023A03J0003).
文摘The exfoliation of bulk 2H-molybdenum disulfide(2H-MoS_(2))into few-layer nanosheets with 1T-phase and controlled layers represents a daunting challenge towards the device applications of MoS_(2).Conventional ion intercalation assisted exfoliation needs the use of hazardous n-butyllithium and/or elaborate control of the intercalation potential to avoid the decomposition of the MoS_(2).This work reports a facile strategy by intercalating Li ions electrochemically with ether-based electrolyte into the van der Waals(vdW)channels of MoS_(2),which successfully avoids the decomposition of MoS_(2)at low potentials.The co-intercalation of Li+and the ether solvent into MoS_(2)makes a first-order phase transformation,forming a superlattice phase,which preserves the layered structure and hence enables the exfoliation of bulk 2H-MoS_(2)into bilayer nanosheets with 1T-phase.Compared with the pristine 2H-MoS_(2),the bilayer 1T-MoS_(2)nanosheets exhibit better electrocatalytic performance for the hydrogen evolution reaction(HER).This facile method should be easily extended to the exfoliation of various transition metal dichalcogenides(TMDs).
基金supported by research grants from the National Key R&D Program of China(No.2017YFB0701604)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110798)+1 种基金Shenzhen Science and Technology Program(Grant No.RCBS20200714114920129)S.Sun also acknowledges the National Natural Science Foundation of China(Grant Nos.11672168 and 12072179)for financial support.
文摘Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries.In this work,a homemade in situ measurement device was used to characterize simultaneously chemical strain and nominal state of charge,especially residual chemical strain and residual nominal state of charge,in graphite-based electrodes at various temperatures.The measurements indicate that raising the testing temperature from 20℃ to 60℃ decreases the chemical strain at the same nominal state of charge during cycling,while residual chemical strain and residual nominal state of charge increase with the increase of temperature.Furthermore,a novel electrochemicalmechanical model is developed to evaluate quantitatively the chemical strain caused by a solid electrolyte interface(SEI)and the partial molar volume of Li in the SEI at different temperatures.The present study will definitely stimulate future investigations on the electro-chemo-mechanics coupling behaviors in lithium-ion batteries.
基金supported by research grants from the National Key R&D Program of China(No.2017YFB0701604)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110798)+1 种基金Shenzhen Science and Technology Program(Grant No.RCBS20200714114920129)S.Sun also acknowledges the National Natural Science Foundation of China(Grant Nos.11672168 and 12072179)for financial support.
文摘Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries.In this work,a homemade in situ measurement device was used to characterize simultaneously chemical strain and nominal state of charge,especially residual chemical strain and residual nominal state of charge,in graphite-based electrodes at various temperatures.The measurements indicate that raising the testing temperature from 20℃ to 60℃ decreases the chemical strain at the same nominal state of charge during cycling,while residual chemical strain and residual nominal state of charge increase with the increase of temperature.Furthermore,a novel electrochemicalmechanical model is developed to evaluate quantitatively the chemical strain caused by a solid electrolyte interface(SEI)and the partial molar volume of Li in the SEI at different temperatures.The present study will definitely stimulate future investigations on the electro-chemo-mechanics coupling behaviors in lithium-ion batteries.
