Ultrafast Laser‐Induced Cathode/Electrolyte Interphase for High‐Voltage Poly(Ethylene Oxide)‐Based Solid Batteries

Abstract Poly(ethylene oxide) (PEO)‐based solid polymer electrolyte promises interfacial compatibility with the high‐capacity metallic anodes in all‐solid‐state batteries (ASSBs). However, the prototype construction is severely hindered by the parasitic ohmic resistance at the electrode‐electrolyte interface, insufficient ionic pathway of the high loading cathode, as well as the PEO oxidation tendency at the high voltage. Herein, a laser‐assisted strategy is presented toward ultra‐efficient cathode modification (completes within 240 s) by constructing continuous, multi‐scale artificial cathode/electrolyte interface (CEI). The tailorable, yet localized temperature gradient induced by the pulsed laser beam can customize the CEI species from the target precursor salts for the on‐demand protection purpose. Derived from the tris(trimethylsilyl)phosphate, the proof‐of‐concept model achieves phosphorus‐rich, ion‐diffusion network across the high‐mass‐loading LiNi_0.8Co_0.1Mn_0.1O₂ cathode, which enables the high‐rate operation of the ASSBs prototype as well as the extended shelf life at the oxidized idling state. Transmission‐mode operando X‐ray phase tracking unravels the electrochemical stability origin at the cathode/PEO interface due to the insulation of electron shuttling, where the layered to spinel phase transition and the lattice oxygen release are alleviated. This generic, readily tailorable, highly‐efficient laser processing strategy thus provides unprecedented opportunities to secure the varieties of energy‐dense, polymer‐based ASSBs.