Amorphous Halide Cathodes Enable 75C All-Solid-State Lithium Batteries

Power delivery in all-solid-state lithium batteries (ASSLBs) is often pursued by maximizing the bulk ionic conductivity of cathode active materials (CAMs), while grain-boundary (GB) ion-transport barriers caused by lattice mismatch remain a major kinetic bottleneck. Here, we reveal that minimizing GB transport barriers, rather than simply enhancing intrinsic conductivity, unlocks ultrafast ion-transport in halide CAMs. Amorphization converts crystalline LiVCl4 into a conformal amorphous phase that preserves short-range V–Cl coordination while minimizing long-range ion-transport tortuosity. Despite lower bulk Li+ conductivity, amorphous LiVCl4 dramatically reduces GB-associated interfacial resistance and enables a catholyte-free cathode (CAM content: 90 wt %) to deliver a capacity of 74.3 mAh g–1 at 5 mA cm–2, compared with 10.2 mAh g–1 for the crystalline counterpart. Meanwhile, the ASSLB further operates across a wide temperature range from −30 to 60 °C and achieves 84.2% capacity utilization at an ultrahigh A-LiVCl4 areal loading of 53.4 mg cm–2. Coupled with amorphous LiTaOCl4, the ASSLB achieves 102.1 mAh g–1 at 20 mA cm–2 (∼75C) and retains 82.3% capacity after 16,000 cycles. These results establish amorphization-enabled conformal interfaces as a new paradigm for ultrahigh-power ASSLBs.