Preparation And Characterization Of Polymer-based Electrolyte All-solid-state Li-ion Battery

All-solid-state lithium-ion-batteries(LIB) with polymer-based electrolyte attract widespread attention due to their inherent safety and high energy density compared with commercial lithium-ion batteries with liquid electrolytes. This paper mainly dicussed the preparation and property research of all-solid-state LIB using polymer-based electrolyte, aiming to broaden the operating temperature range of all-solid-state LIB with polymer-based electrolyte and promote the commeracialization of all-solid-state LIB. Polyethylene oxide(PEO)-based solid-polymer-electrolyte(SPE) was prepared by solution-cast. Inorganic filler was doped to improve ionic conductivity under room temperature and the mechanical strength of SPE. All-solid-state LIB was prepared by SPE matching with the commercial cathode materials in order to study its electrochemical properties under both room and high temperature.PEO-based SPE was prepared by solution-cast and hot pressing with smooth-surface and uniform-thickness(150 μm). The room temperature ionic conductivity, electrochemical window, thermal stability and chemical stability of PEO-based SPE have been measured. This paper dicussed the modification of PEO-based SPE by changing the ratio of Li1.5Al0.5Ge1.5(PO4)3(LAGP, NASICON type inorganic solid electrolyte) filler. With 20mass%-LAGP, the room temperature ionic conductivity of PEO-based SPE reaches 7.5×10-5 S/cm, and the stability electrochemical window more than 5 V.We prepared the all-solid-state LIB with the LFP cathode and lihium metal anode. Subsequently, heat treatment process has been taken to get good contact of electrode-electrolyte interface. At room temperature, the first discharge capacity of LFP/SPE(5 mass%-LAGP) /Li was 150.13 m Ah/g(columbic efficiency was 95.99%) and the capacity retention was 80% after 300 cycles at 0.1 C. The first discharge capacity of LFP/SPE(15 mass%-LAGP) /Li was 114.3 m Ah/g and the capacity retention was 84.2% after 500 cycles at 1 C. Furthermore, in order to pursue the higher energy density of batteries, different high voltage cathode materials(LMFP and NCM) all-solid-state LIB were prepared to study the compatibility of electrode-electrolyte interface. Analyze the reason for capacity fading and attempt to improve the electrochemical performance by targeted approch.