Towards long-life 500 Wh kg−1 lithium metal pouch cells via compact ion-pair aggregate electrolytes

Abstract

The development of practical lithium metal cells is plagued by their limited lifespan, primarily due to the poor interfacial stability of the electrolytes. Here we present a compact ion-pair aggregate (CIPA) electrolyte that enables high-performance Li metal pouch cells under lean electrolyte conditions. The electrolyte features a unique nanometre-scale solvation structure in which ion pairs are densely packed to form large CIPAs, in contrast to conventional electrolytes that comprise small aggregates. Notably, the CIPAs facilitate fast interfacial reduction kinetics on the Li metal anode via a collective electron-transfer process, leading to the formation of a stable interface. A 505.9 Wh kg−1 Li metal pouch cell with a high-nickel-content cathode (LiNi0.905Co0.06Mn0.035O2) exhibited a 91% energy retention after 130 cycles. This work demonstrates nanostructured electrolyte design for realizing high-performance Li metal batteries. It also showcases the importance of understanding interfacial reaction mechanisms in the design and development of electrolytes. Electrolyte design is crucial for lithium metal battery development. Here the authors report an electrolyte with a compact solvation structure on the nanometre scale that facilitates fast interfacial reaction kinetics and improves battery performance.