High voltage stable solid-state lithium battery based on the nano-conductor imbedded flexible hybrid solid electrolyte with hyper-ion conductivity and thermal, mechanical, and adhesive stability

Abstract

Hybrid solid electrolyte (HSE) is a potential candidate in lithium secondary battery to replace the traditional liquid electrolyte with the superiority of solid state. We propose an optimal design for the high voltage stable solid-state lithium battery system by combining the HSE composed of poly(vinyl alcohol)-g-pyrrole-2-carboxylic acid (PVA-g-PCA) and pyrrole-2-carboxylic acid modified hydrotalcite (HTpca) nano-conductor and the Al2O3 coated LiCoO2 active material. The flexible and non-flammable PVA-g-PCA-80IL-5HTpca HSE exhibits outstanding Li+ conductivity of 4.78 × 10−3 S cm−1 and Li+ transference number of 0.72 at room temperature in a wide electrochemical window up to 5.17 V vs Li+/Li, maintaining the long-term stability with Li metal over 500 cycles and low interfacial resistance of 42 Ω cm2 with cathode prepared by PVA-g-PCA-60IL-5HTpca. Utilized as a conductive binder, PVA-g-PCA-60IL-5HTpca HSE ensures the dense packing and uniform distribution of LiCoO2 particles and the excellent adhesion strength with the current collector (>24 MPa). Assembled with the Al2O3 coated LiCoO2 active material, the solid-state lithium batteries display the specific capacity of 188.7 mAh g−1 and the long-term cycling stability over 200 cycles at 4.5 V and 60 °C.