Rational Design of Electrolyte and Interphase Formation for Solid-State Batteries

Abstract

Solid-state batteries (SSBs) using inorganic solid-state electrolytes (SSEs) are widely regarded as the next-generation energy storage system, which may replace the state-of-the-art Li-ion batteries with flammable organic electrolytes. However, the interfacial issues, including large interfacial resistance and dendrite generation, have always frustrated the development of high-energy SSBs. For the first time, we report that infusing the garnet-type Li-ion solid electrolytes (GSEs) with air-stable electrolyte Li3PO4 (LPO) dramatically reduces the interfacial resistance to ~1 Ω cm2 on anode side and achieves a high critical current density of 2.2 mA cm-2 under ambient condition due to enhanced interfacial stability to Li metal anode. The coated and infused LPO electrolytes not only improve the mechanical strength and Li-ion conductivity of grain boundaries, but also form a stable LPO-derived solid-electrolyte interphase between Li metal and GSEs, which eliminates the Li dendrites growth and prevents the direct reduction of GSEs by Li metal over a long cycle life.Relying on the gained interface mechanisms, we further designed a new type of low-temperature beta-alumina solid electrolyte-based Na metal battery which has low interfacial impedance and extremely high critical current density for fast charging and discharging, outperforming all other types of solid or semi-solid state batteries to date. Overall, the interface engineering approaches together with grain-boundary modification on SSEs represent the promising strategy to revolutionize the electrode-electrolyte interface chemistry for SSBs and provides new design strategy for other-types of solid-state batteries.