Role of solid–liquid interphases in lithium batteries

Interfacial problems between electrodes and electrolytes are common for lithium batteries. The local interfacial chemistry is governed by the interaction of chemical heterogeneity and microstructural complexity. Designing lithium batteries with steady ion transport kinetics requires a thorough understanding of solid–liquid interphases. Hence, we have reviewed the two common interphases in liquid lithium-ion batteries, solid-electrolyte interphase (SEI) and cathode-electrolyte interphase (CEI), and the newly-identified interphase (solid–liquid electrolyte interphase, SLEI) in solid-state lithium metal batteries. For each type of interphase, more insights are provided regarding the underlying interfacial transport mechanism, chemical composition, and micro- and/or nano-structural optimizations. This chapter highlights the importance of designing robust solid–liquid interphases that could enable next-generation lithium batteries with increased cycling performance and lifespan.