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The drying rate would significantly affect the quality of the composite electrode after solidification. In order to clarify the underlying effect mechanism of ingredient heterogeneity in the electrode caused by the drying process on the mechanical integrity of lithium secondary batteries in service, an integrated analysis approach is developed to determine the mechanical properties and lithium diffusion-induced stress of the composite electrode with gradient distributed binder and conductive agent. A faster solidification is found to broaden the inhomogeneous extent of inactive components in the electrode coating across its thickness, markedly. As a result, it will not only enlarge the tensile stress in the brittle electrode upon electrochemical operation due to the increased effective modulus of composite near the surface, but will also impair the interfacial strength between the active layer and current collector. Moreover, a two-stage drying protocol (initially fast, followed by slow evaporation of solvent) is found to be greatly beneficial to boosting the resistance to cohesion failure and surface damage of the composite electrode, and the optimized processing parameters are proposed to obtain a robust production with high efficiency. [ABSTRACT FROM AUTHOR]

The prediction of electrochemical performance is the basis for long-term service of all-solid-state-battery (ASSB) regarding the time-aging of solid polymer electrolytes. To get insight into the influence mechanism of electrolyte aging on cell fading, we have established a continuum model for quantitatively analyzing the capacity evolution of the lithium battery during the time-aging process. The simulations have unveiled the phenomenon of electrolyte-aging-induced capacity degradation. The effects of discharge rate, operating temperature, and lithium-salt concentration in the electrolyte, as well as the electrolyte thickness, have also been explored in detail. The results have shown that capacity loss of ASSB is controlled by the decrease in the contact area of the electrolyte/electrode interface at the initial aging stage and is subsequently dominated by the mobilities of lithium-ion across the aging electrolyte. Moreover, reducing the discharge rate or increasing the operating temperature can weaken this cell deterioration. Besides, the thinner electrolyte film with acceptable lithium salt content benefits the durability of the ASSB. It has also been found that the negative effect of the aging electrolytes can be relieved if the electrolyte conductivity is kept being above a critical value under the storage and using conditions. [ABSTRACT FROM AUTHOR]

Ensuring the material durability of an electrolyte is a prerequisite for the long-term service of all-solid-state batteries (ASSBs). Herein, to investigate the mechanical integrity of a solid polymer electrolyte (SPE) in an ASSB upon electrochemical operation, we have implemented a sequence of quasi-static uniaxial tension and stress relaxation tests on a lithium perchlorate-doped poly (vinyl alcohol) electrolyte, and then discussed the viscoelastic behavior as well as the strength of SPE film during the physical aging process. On this basis, a continuum electrochemical-mechanical model is established to evaluate the stress evolution and mechanical detriment of aging electrolytes in an ASSB at a discharge state. It is found that the measured elastic modulus, yield stress, and characteristic relaxation time boost with the prolonged aging time. Meanwhile, the shape factor for the classical time-decay equation and the tensile rupture strength are independent of the aging history. Accordingly, the momentary relaxation modulus can be predicted in terms of the time–aging time superposition principle. Furthermore, the peak tensile stress in SPE film for the full discharged ASSB will significantly increase as the aging proceeds due to the stiffening of the electrolyte composite. It may result in the structure failure of the cell system. However, this negative effect can be suppressed by the suggested method, which is given by a 2D map under different lithiation rates and relative thicknesses of the electrolyte. These findings can advance the knowledge of SPE degradation and provide insights into reliable all-solid-state electrochemical device applications. [ABSTRACT FROM AUTHOR]