MXene Electrodes for All Strain-Free Solid-State Batteries

All-solid-state batteries with nonflammable inorganic solid electrolytes are the key to addressing the safety issues of lithium-ion batteries with flammable organic liquid electrolytes. However, conventional electrode materials suffer from substantial volume changes during Li⁺ (de)intercalation, leading to mechanical failure of interfaces between electrode materials and solid electrolytes and then severe performance degradation. In this study, we report strain-free charge storage via the interfaces between transition metal carbides (MXenes) and solid electrolytes, where MXene shows negligible structural changes during Li⁺ (de)intercalation. Operando scanning electron transmission microscopy with electron energy-loss spectroscopy reveals the pillar effect of trapped Li⁺ in the interlayer spaces of MXene to achieve the strain-free features. An all strain-free solid-state battery, which consists of a strain-free Ti₃C₂T_x negative electrode and a strain-free disordered rocksalt Li_8/7Ti_2/7V_4/7O₂ positive electrode, demonstrates long-term stable operation while preserving the interfacial contact between electrode materials and solid electrolytes.