Electrochemical characterization of in situ polymerized composite solid electrolyte incorporating three dimensional Li1·5Al0.5Ge1.5(PO4)3 framework

Abstract

In pursuit of safer lithium-ion batteries, research is veering towards all-solid-state lithium batteries (ASSLBs) featuring solid electrolytes due to the safety concerns and low metal interfacial compatibility of liquid electrolytes. ASSLBs combined with composite solid electrolytes (CSEs) incorporating NASICON-type active fillers are especially appealing because of their inherent safety, ease of production, and high energy density. This study introduces a Li1·5Al0.5Ge1.5(PO4)3 (LAGP) framework created via tape casting and in situ thermal polymerization, achieving a CSE with notable ionic conductivity (0.791 mS cm−1), electrochemical stability up to 5.09 V, and a lithium-ion transference number of 0.72 at 30 °C. The Li|CSE|Li cell demonstrates low overpotential over 1000 h, and the Li|CSE|NCM811 coin cell delivers a discharge capacity of 180.9 mAh g−1, maintaining 84.6 % capacity after 200 cycles. Moreover, the Li|CSE|NCM811 pouch cell upholds a capacity of 116.41 mAh g−1 after 100 cycles, underscoring the 3D LAGP framework and in situ polymerization's role in enhancing ASSLB safety and functionality.