Experimental study on the internal damage evolution and stiffness decay of all-solid-state lithium metal battery charging and discharging
All-solid-state lithium metal batteries(Li-SSB)have received a lot of attention in recent years due to their high safety,flexible designability and large energy density.This paper addresses the issue of internal damage evolution and stiffness degradation of solid-state electrolytes during long service cycles,and investigates the damage evolution of Li6.4La3Zr1.4TaO12(LLZTO)solid oxide electrolytes during the long-cycle charge and discharge of Li-SSB using high-resolution X-ray computed tomography(X-CT).The internal structure of the Li/LLZTO/Li symmetric cell structure at two current density operating conditions of 0.3mA/cm2 and 0.5mA/cm2 with different cycle times was obtained for three-dimensional reconstruction,and the internal pore evolution law of the LLZTO electrolyte was obtained quantitatively by using the grey-scale feature extraction method of the image,and the dimensionless elastic modulus of the porous structure of the LLZTO solid-state electrolyte was studied by establishing the decay effect of the modulus of the LLZTO solid electrolyte with the charging and discharging process was studied by establishing a model.The experimental results show that the mechanical damage rate of the electrolyte in Li-SSB increases with increasing current density,the degree of electrolyte damage in the service phase of the battery is highly positively correlated with the cyclic polarization voltage,and the evolution of electrolyte damage after short-circuiting of the battery shows an evolutionary pattern of intense first and then gentle.The result of this paper further reveals the law of internal cell loss evolution during electrochemical cycling,which has implications for the improvement and design of high-performance all-solid-state lithium metal batteries.
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