Solid-state batteries have received increasing attention in scientific and industrial communities,which benefits from the intrinsically safe solid electrolytes(SEs).Although much effort has been devoted to designing S...Solid-state batteries have received increasing attention in scientific and industrial communities,which benefits from the intrinsically safe solid electrolytes(SEs).Although much effort has been devoted to designing SEs with high ionic conductivities,it is extremely difficult to fully understand the ionic diffusion mechanisms in SEs through conventional experimental and theoretical methods.Herein,the temperature-dependent concerted diffusion mechanism of ions in SEs is explored through machinelearning molecular dynamics,taking Li_(10)GeP_(2)S_(12) as a prototype.Weaker diffusion anisotropy,more disordered Li distributions,and shorter residence time are observed at a higher temperature.Arrhenius-type temperature dependence is maintained within a wide temperature range,which is attributed to the linear temperature dependence of jump frequencies of various concerted diffusion modes.These results provide a theoretical framework to understand the ionic diffusion mechanisms in SEs and deepen the understanding of the chemical origin of temperature-dependent concerted diffusions in SEs.展开更多
Electric double layer(EDL)is a critical topic in electrochemistry and largely determines the working performance of lithium batteries.However,atomic insights into the EDL structures on heteroatom-modified graphite ano...Electric double layer(EDL)is a critical topic in electrochemistry and largely determines the working performance of lithium batteries.However,atomic insights into the EDL structures on heteroatom-modified graphite anodes and EDL evolution with electrode potential are very lacking.Herein,a constant-potential molecular dynamics(CPMD)method is proposed to probe the EDL structure under working conditions,taking N-doped graphite electrodes and carbonate electrolytes as an example.An interface model was developed,incorporating the electrode potential and atom electronegativities.As a result,an insightful atomic scenario for the EDL structure under varied electrode potentials has been established,which unveils the important role of doping sites in regulating both the EDL structures and the following electrochemical reactions at the atomic level.Specifically,the negatively charged N atoms repel the anions and adsorb Li~+at high and low potentials,respectively.Such preferential adsorption suggests that Ndoped graphite can promote Li~+desolvation and regulate the location of Li~+deposition.This CPMD method not only unveils the mysterious function of N-doping from the viewpoint of EDL at the atomic level but also applies to probe the interfacial structure on other complicated electrodes.展开更多
All-solid-state lithium metal batteries(ASSLMBs)are considered as one of the ultimate goals for the development of energy storage systems due to their high energy density and high safety.However,the mismatching of int...All-solid-state lithium metal batteries(ASSLMBs)are considered as one of the ultimate goals for the development of energy storage systems due to their high energy density and high safety.However,the mismatching of interface transport kinetics as well as interfacial instability induces the growth of lithium dendrite and thus,leads to severe degradation of battery electrochemical performances.Herein,an integrated interface configuration(IIC)consisting of in-situ generated Li I interphase and Li-Ag alloy anode is proposed through in-situ interface chemistry.The IIC is capable of not only regulating charge transport kinetics but also synchronously stabilizing the lithium/electrolyte interface,thereby achieving uniform lithium platting.Therefore,Li||Li symmetric cells with IIC achieve a critical current density of up to 1.6 mA cm^(-2)and achieve stable cycling over 1600 hours at a high current density of 0.5 mA cm^(-2).Moreover,a high discharge capacity of 140.1 mA h g-1at 0.1 C is also obtained for the Li(Ni_(0.6)Co_(0.2)Mn_(0.2))O_(2)(NCM622)full battery with a capacity retention of 65.6%after 300 cycles.This work provides an effective method to synergistically regulate the interface transport kinetics and inhibit lithium dendrite growth for high-performance ASSLMBs.展开更多
Understanding the intrinsic activity of oxygen evolution reaction(OER) is crucial for catalyst design.To date,different metal-doping strategies have been developed to achieve this,but the involving mechanisms remain u...Understanding the intrinsic activity of oxygen evolution reaction(OER) is crucial for catalyst design.To date,different metal-doping strategies have been developed to achieve this,but the involving mechanisms remain unclear.Here,the electronic structure of the transition metal-doped NiFe_(2)O_(4)(001) surface is scrutinized for OER intrinsic activity using density functional theory calculations.Five 3d-orbital filling metals(Ti,V,Cr,Mn,and Co) are introduced as dopants onto A-and B-layers of the NiFe_(2)O_(4)(001) surface,and variation of oxidation states over Fe sites is observed on B-layer.Analyzing the magnetic moment and charge transfer of surface cation sites reveals that the variation of Fe oxidation states originates from the super-exchange effect and is influenced by the t2g-electron configuration of 3d metal dopants.This trend governs the generation of highly-active Fe3+sites on the B-layer,the adsorption strength of OER intermediates,i.e.,*O and*OH,and therefore the intrinsic activity.The finding of super-exchange mechanism induced by 3d early metal doping offers insights into electronic structure tailoring strategies for improving the intrinsic activity of OER electrocatalysts.展开更多
基金supported by the National Key Research and Development Program(2021YFB2500210)the Beijing Municipal Natural Science Foundation(Z20J00043)+4 种基金the National Natural Science Foundation of China(22109086 and 21825501)the China Postdoctoral Science Foundation(2021TQ0161 and 2021 M691709)the Guoqiang Institute at Tsinghua University(2020GQG1006)the support from the Shuimu Tsinghua Scholar Program of Tsinghua Universitythe support from the Tsinghua National Laboratory for Information Science and Technology for theoretical simulations。
文摘Solid-state batteries have received increasing attention in scientific and industrial communities,which benefits from the intrinsically safe solid electrolytes(SEs).Although much effort has been devoted to designing SEs with high ionic conductivities,it is extremely difficult to fully understand the ionic diffusion mechanisms in SEs through conventional experimental and theoretical methods.Herein,the temperature-dependent concerted diffusion mechanism of ions in SEs is explored through machinelearning molecular dynamics,taking Li_(10)GeP_(2)S_(12) as a prototype.Weaker diffusion anisotropy,more disordered Li distributions,and shorter residence time are observed at a higher temperature.Arrhenius-type temperature dependence is maintained within a wide temperature range,which is attributed to the linear temperature dependence of jump frequencies of various concerted diffusion modes.These results provide a theoretical framework to understand the ionic diffusion mechanisms in SEs and deepen the understanding of the chemical origin of temperature-dependent concerted diffusions in SEs.
基金supported by the National Natural Science Foundation of China(T2322015,22209094,22209093,and 22109086)the National Key Research and Development Program(2021YFB2500300)+2 种基金the Open Research Fund of CNMGE Platform&NSCC-TJOrdos-Tsinghua Innovative&Collaborative Research Program in Carbon Neutralitythe Tsinghua University Initiative Scientific Research Program。
文摘Electric double layer(EDL)is a critical topic in electrochemistry and largely determines the working performance of lithium batteries.However,atomic insights into the EDL structures on heteroatom-modified graphite anodes and EDL evolution with electrode potential are very lacking.Herein,a constant-potential molecular dynamics(CPMD)method is proposed to probe the EDL structure under working conditions,taking N-doped graphite electrodes and carbonate electrolytes as an example.An interface model was developed,incorporating the electrode potential and atom electronegativities.As a result,an insightful atomic scenario for the EDL structure under varied electrode potentials has been established,which unveils the important role of doping sites in regulating both the EDL structures and the following electrochemical reactions at the atomic level.Specifically,the negatively charged N atoms repel the anions and adsorb Li~+at high and low potentials,respectively.Such preferential adsorption suggests that Ndoped graphite can promote Li~+desolvation and regulate the location of Li~+deposition.This CPMD method not only unveils the mysterious function of N-doping from the viewpoint of EDL at the atomic level but also applies to probe the interfacial structure on other complicated electrodes.
基金supported by the Beijing Natural Science Foundation(L223009)the National Natural Science Foundation of China(22075029)+1 种基金the National Key Research and Development Program of China(2021YFB2500300)the Key Research and Development(R&D)Projects of Shanxi Province(2021020660301013)。
文摘All-solid-state lithium metal batteries(ASSLMBs)are considered as one of the ultimate goals for the development of energy storage systems due to their high energy density and high safety.However,the mismatching of interface transport kinetics as well as interfacial instability induces the growth of lithium dendrite and thus,leads to severe degradation of battery electrochemical performances.Herein,an integrated interface configuration(IIC)consisting of in-situ generated Li I interphase and Li-Ag alloy anode is proposed through in-situ interface chemistry.The IIC is capable of not only regulating charge transport kinetics but also synchronously stabilizing the lithium/electrolyte interface,thereby achieving uniform lithium platting.Therefore,Li||Li symmetric cells with IIC achieve a critical current density of up to 1.6 mA cm^(-2)and achieve stable cycling over 1600 hours at a high current density of 0.5 mA cm^(-2).Moreover,a high discharge capacity of 140.1 mA h g-1at 0.1 C is also obtained for the Li(Ni_(0.6)Co_(0.2)Mn_(0.2))O_(2)(NCM622)full battery with a capacity retention of 65.6%after 300 cycles.This work provides an effective method to synergistically regulate the interface transport kinetics and inhibit lithium dendrite growth for high-performance ASSLMBs.
基金supported by the Australian Research Council(FT170100224,DP210103892,IC200100023)support from Tsinghua National Laboratory for Information Science and Technology for theoretical simulations。
文摘Understanding the intrinsic activity of oxygen evolution reaction(OER) is crucial for catalyst design.To date,different metal-doping strategies have been developed to achieve this,but the involving mechanisms remain unclear.Here,the electronic structure of the transition metal-doped NiFe_(2)O_(4)(001) surface is scrutinized for OER intrinsic activity using density functional theory calculations.Five 3d-orbital filling metals(Ti,V,Cr,Mn,and Co) are introduced as dopants onto A-and B-layers of the NiFe_(2)O_(4)(001) surface,and variation of oxidation states over Fe sites is observed on B-layer.Analyzing the magnetic moment and charge transfer of surface cation sites reveals that the variation of Fe oxidation states originates from the super-exchange effect and is influenced by the t2g-electron configuration of 3d metal dopants.This trend governs the generation of highly-active Fe3+sites on the B-layer,the adsorption strength of OER intermediates,i.e.,*O and*OH,and therefore the intrinsic activity.The finding of super-exchange mechanism induced by 3d early metal doping offers insights into electronic structure tailoring strategies for improving the intrinsic activity of OER electrocatalysts.
