Interface Welding via Thermal Pulse Sintering to Enable 4.6 V Solid‐State Batteries

NASICON‐type Li1.3Al0.3Ti1.7(PO4)3 (LATP) is one of the most promising solid‐state electrolytes (SSEs) to achieve high‐energy‐density solid‐state batteries (SSBs) due to its high ionic conductivity, high‐voltage stability, and low cost. However, its practical application is constrained by inadequate interfacial compatibility with cathode materials and significant incompatibility with lithium metal. In this work, a cost‐effective interface welding approach is reported, utilizing an innovative thermal pulse sintering (TPS) to fabricate LATP‐based solid‐state batteries. Initially, the rapid thermal pulses enhance the ionic conductivity of LATP SSE by inducing selective growth of LATP nanowires, effectively occupying interparticle voids. Additionally, this process results in the formation of a dense layer (GCM) comprising graphene oxide, carbon nanotubes, and MXene with a controlled Li+ transport pathway, facilitating lithium stripping and plating processes. Moreover, these thermal pulses facilitate the interfacial fusion between LATP and cathode materials, while avoiding undesired phase diffusion. As a result, SSBs with a LiCoO2 cathode deliver favorable cycle stability at 4.6 V, marking significant progress. This facile interface welding strategy represents a substantial step toward high‐energy‐density SSB development. In this study, a thermal pulse sintering strategy is reported for the facile integration of high‐voltage solid‐state batteries. During the rapid sintering process, well‐soldered interfaces between cathode materials, ceramic solid electrolytes, and anode interlayers are constructed, promoting interfacial Li+ conduction. Moreover, the impurity‐free interfaces facilitate stable cycling of solid‐state lithium batteries at 4.6 V.