A Bridge between Ceramics Electrolyte and Interface Layer to Fast Li+ Transfer for Low Interface Impedance Solid‐State Batteries

Abstract

AbstractSolid‐state batteries (SSBs) are regarded as next generation advanced energy storage technology to provide higher safety and energy density. However, a practical application is plagued by large interfacial resistance, owing to solid‐solid interface contact between ceramics electrolytes and Li anode. Introducing polymer‐based coating between electrolytes and Li anode is a feasible strategy to solve this issue. Unfortunately, current polymer is hard to achieve intimate contact at the atomic scale and lacks of a bridge to transfer Li+ quickly between electrolytes and polymer coating. This gives rise to sluggish Li+ transfer dynamics, huge interface impedance and greatly limits the effectiveness of this strategy. Herein, Poly(lithium 4‐styrenesulfonate)(PLSS) is introduced between Li6.5La3Zr1.5Ta0.5O12 (LLZTO) electrolyte and Li anode. The theories and experiments prove the existence of strong coordinating interaction between SO3Li in PLSS and atoms on LLZTO surface. This interaction structures a bridge to migrate Li+ fast across LLZTO/PLSS interface and hence interface impedance is as low as 9 Ω cm2. Moreover, the electron‐blocking feature of PLSS can prevent electrons from tunneling the LLZTO/PLSS interface and combining with Li+ to form dendrite within LLZTO. PLSS‐base cells show improved long‐life cycling for 4700 h at 0.1 mA cm−2 at room temperature.