A Li₂S-based all-solid-state battery with high energy and superior safety

Safety risks stem from applying extremely reactive alkali metal anodes and/or oxygen-releasing cathodes in flammable liquid electrolytes restrict the practical use of state-of-the-art high-energy batteries. Here, we propose a intrinsically safe solid-state cell chemistry to satisfy both high energy and cell reliability. An all-solid-state rechargeable battery is designed by energetic yet stable multielectron redox reaction between Li₂S cathode and Si anode in robust solid-state polymer electrolyte with fast ionic transport. Such cells can deliver high specific energy of 500 to 800 Wh kg⁻¹ for 500 cycles with fast rate response, negligible self-discharge, and good temperature adaptability. Integrating intrinsic safe cell chemistry to robust cell design further guarantees reversible energy storage against extreme abuse of overheating, overcharge, short circuit, and mechanical damage in the air and water. This work may shed fresh insight into bridging the huge gap between high energy and safety of rechargeable cells for feasible applications and recycle.