Composite Electrode-Hybrid Electrolyte Integration Strategy for Enhanced Ion Transport and Scalable All-Solid-State Lithium Batteries

Abstract

Achieving both high energy density and long-term cyclability in all-solid-state lithium batteries (ASSBs) remains a formidable challenge, particularly under high-cathode-loading conditions, where interfacial instability and through-plane Li+ transport limitations compromise performance. This study reports a synergistic design that combines a hybrid solid electrolyte (HSE) and a composite electrode (CE) incorporating ball-milled Al-doped Li6.28Al0.24La3Zr2O11.98 (BM Al-LLZO) to address these bottlenecks. The HSE, containing 3 wt% BM Al-LLZO dispersed in a poly (ethylene oxide)-based, in situ polymerized matrix, exhibits enhanced ionic conductivity (1.04 & times; 10-3 S cm-1) and a high Li-ion transference number (t+ = 0.661) owing to uniform filler dispersion and strong polymer-ceramic interfacial synergy. However, particle confinement at the electrode surface limits bulk ion percolation. To overcome this issue, a CE architecture with BM Al-LLZO homogeneously embedded throughout the cathode matrix is proposed. This design significantly reduces ionic resistance and enables continuous transport pathways. Consequently, the CE||SPE||Li cell delivers excellent performance, retaining 71.55 % of its initial capacity after 200 cycles at 0.5C, while a high-loading pouch cell demonstrates scalable applicability with over 90 % coulombic efficiency. These findings underscore the critical role of interfacial engineering in ASSBs and provide a practical route toward high-performance, scalable solid-state battery systems.