Ultra-thin and high-voltage-stable Bi-phasic solid polymer electrolytes for high-energy-density Li metal batteries

Solid-state electrolytes (SSEs) are essential materials in all -solid-state lithium -metal batteries. However, a comprehensive SSE possessing high ionic conductivity, broad electrochemical window, and high thermal stability remains elusive. In this work, a novel bi-phase SSE featuring a shape memory effect is developed by in -situ thermal cross -linking of 2 -ethyl cyanoacrylate (CA), polyethylene glycol methyl ether acrylate (PEGMEA), succinonitrile (SN), and fluoroethylene carbonate (FEC) additives. Due to the phase separation phenomenon and interfacial Li -ion conduction, the bi-phase SSE exhibits a room -temperature ionic conductivity of 1.9 mS cm( -1). Meanwhile, the bi-phase SSE exhibits a high oxidation potential of 4.9 V (vs Li/Li+), and a lithium -ion transference number (t(Li+)) of 0.56. Coupling with LiNi0.8Co0.1Mn0.1O2 (NCM 811) cathode and 11 mu m bi-phase SSE, solid-state lithium metal batteries (SSLMBs) demonstrate long-term cycling stability (capacity retention > 92% after 250 cycles), excellent rate performance (126 mA h g(-1) at 2 C, and high -voltage stability (208 mA h g(-1) at 4.5 V). This investigation demonstrates the potential of bi-phase SSEs as a promising material for the development of high-performance SSLMBs.