Mechanical Integrity Degradation and Control of All-Solid-State Lithium Battery with Physical Aging Poly (Vinyl Alcohol)-Based Electrolyte.

Yaolong He,Hongjiu Hu,Shufeng Li,Sihao Zhou

doi:10.3390/polym12091886

Abstract

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.

Highlights

With the deepening research on all-solid-state batteries (ASSBs), an intensive scientific interest in the development of inherent safety, non-leakage, and stable high-performance electrochemical equipment has emerged to accommodate a wide range of new engineering applications, including medical implants, flexible electronics, and textiles [1,2]
To obtain a30 days maximum influence of the electrochemical at the completely discharged state for the film after of aging was about one a half on the solid electrolyte, the active materials were completely lithiated with aand constant current−constant times that of the one-day-aged specimen. These findings indicate that physical aging of the film loading on the solid electrolyte, the active materials were completely lithiated with a constant voltage operation through the described above.The related model parameters are may degrade the method structure firmness of an ASSBin andSection need to be 3 controlled
(2) The KWW time-decay function could describe the evolution of elastic modulus for aging solid polymer electrolyte (SPE) during the stress relaxation period

Summary

Introduction

With the deepening research on all-solid-state batteries (ASSBs), an intensive scientific interest in the development of inherent safety, non-leakage, and stable high-performance electrochemical equipment has emerged to accommodate a wide range of new engineering applications, including medical implants, flexible electronics, and textiles [1,2]. In contrast to inorganic counterparts with a brittle crystalline phase, the solid polymer electrolyte (SPE) exhibits excellent interfacial compatibility, and superior elasticity to endure greater mechanical deformation, contributing to be cast into the complicated architectures for lithium-ion and lithium-metal batteries [3,4,5]. The rich hydroxyl groups attached to the polymer chain of PVA provide strong hydrogen binding, contributing to an excellent mechanical stability and high melting point [33]. The physical aging process of SPEs and its effects on ASSB performance is a pivotal scientific problem to be solved

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Conclusion