Fig. 1: Schematic of the reaction mechanism at cathode/electrolyte interface in (a) the primary all-solid-state LIB and (b) a rechargeable all-solid-state LIB in this work.

In the primary all-solid-state LIB, the solid-phase conversion process between I₂ and I⁻ suffers from a sluggish kinetics and leads to a poor rechargeability for the battery. In our proposed rechargeable all-solid-state LIB, a two-step polyiodide chemistry with fast kinetics and high reversibility is realized by the confined dissolution strategy. The polyiodides could be well dissolved in the dispersion layer, but their shuttling is avoided by the blocking layer. During the discharge process the I₅⁻ is first discharged to I₃⁻ and then to I⁻. The charge process follows a conversion reaction from I⁻ to I₃⁻ and finally I₅⁻. Note that I₂ accepts electron from KB to form I₅⁻ and is then dissolved in the dispersion layer.