| In recent years,with the rapid development of electrical portable devices and electric vehicles,the existing lithium-ion batteries(LIBs)cannot satisfy the continuously surging demands for capacity and fast charging.Therefore,it is necessary to gain an further understanding of the reaction processes and degradation mechanism.During charge–discharge cycling,in situ measurements can reveal more important information about the electrode materials than ex situ characterization techniques.The development of the new in situ/operando techniques to study advanced electrode materials is so crucial to the development of lithium-ion batteries.We design and fabricate a kind of in-situ nanoscale electrochemical device to simulate the actual operating environment of lithium ion batteries.In this nanobattery,the nanosheet and metallic Li are used as the working and counter electrode respectively.The device is fully filled with electrolyte and allows in-situ investigation of optical and Raman properties.It is the first time to capture a set of in situ observations where the anisotropy of electrode material influences the diffusion behavior of lithium ions.High quality GeP single crystal was prepared by Flux method,and GeP nanosheets were obtained by mechanical exfoliation.The crystal orientation of nanosheet and crystal planes were determined by characterization.The crystal orientation of the x-axis is [102],the crystal orientation of the y-axis is [010],and the upper surface of the nanosheet is(-201).The in-situ optical microscope was used to characterize the discharge process of the nanosheet.It was found that the diffusion speed of lithium ions in the x-axis of GeP nanosheets was much higher than that in the y-axis.Consistent with theoretical calculations,the Li-ion diffusion energy barrier along the [010] direction of GeP is lower than the [102] direction.By in situ Raman characterization,the process of nanosheets change from crystalline state to amorphous state during discharge prosess. |
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