Ultrahigh-Rate All-Solid-State Batteries with a Dendrite-Free LiAl Anode via Compositional and Structural Engineering

Conventional lithium-ion batteries with graphite anodes and flammable liquid electrolytes face energy density and safety limitations. All-solid-state batteries (ASSBs) offer improved safety but suffer from lithium dendrite growth and interfacial instability. Here, a LiAl solid solution anode is developed via melting isothermal processing and compaction. Among the compositions tested (LiAl-1:3, LiAl-1:4, and LiAl-1:5), LiAl-1:4 delivers optimal performance. Symmetric cells achieve a critical deposition current density of 1.35 mA cm–2 and stable cycling for 800 h at 3 mA cm–2. Full cells with LiNi0.9Co0.05Mn0.05O2 cathodes exhibit high-rate capability (110.4 mAh g–1 at 30C) and outstanding longevity: 89.1% capacity retention after 1000 cycles at 1C (8.34 mg cm–2), over 17 000 cycles at 20C, and 12 000 cycles at 100C (2.29 mg cm–2). Characterization reveals that uniform Al distribution and a porous structure suppress dendrites and stabilize interfaces, while surface Li2O enhances Li+ transport. This work establishes design principles for high-power ASSBs via stoichiometric and microstructural optimization.