All-solid-state batteries require advanced cathode designs to realize their potential for high energy density and economic viability1–3. Integrated all-in-one cathodes, which eliminate inactive conductive additives and heterogeneous interfaces, hold promise for substantial energy and stability gains but are hindered by materials lacking sufficient Li+/e− conductivity, mechanical robustness and structural stability4–14. Here we present Li1.3Fe1.2Cl4, a cost-effective halide material that overcomes these challenges. Leveraging reversible Fe2+/Fe3+ redox and rapid Li+/e− transport within its framework, Li1.3Fe1.2Cl4 achieves an electrode energy density of 529.3 Wh kg−1 versus Li+/Li. Critically, Li1.3Fe1.2Cl4 shows unique dynamic properties during cycling, including reversible local Fe migration and a brittle-to-ductile transition that confers self-healing behaviour. This enables exceptional cycling stability, maintaining 90% capacity retention for 3,000 cycles at a rate of 5 C. Integration of Li1.3Fe1.2Cl4 with a nickel-rich layered oxide further increases the energy density to 725.6 Wh kg−1. By harnessing the advantageous dynamic mechanical and diffusion properties of all-in-one halides, this work establishes all-in-one halides as an avenue for energy-dense, durable cathodes in next-generation all-solid-state batteries.
