Dispersed Sodophilic Phase Induced Bulk Phase Reconstruction of Sodium Metal Anode for Highly Reversible Solid‐State Sodium Batteries

Abstract

Solid‐state sodium batteries (SSSBs) face critical challenges related to interfacial instability and dendritic growth at the interfaces between the sodium metal anode and solid‐state electrolyte (SSE). In this work, a composite anode incorporating a dispersed sodophilic Na2In phase is synthesized by melting a mixture of 5 wt% indium and 95 wt% sodium at 180 °C. This bulk phase reconstruction strategy introduces a large number of sodophilic sites both on the surface and inside the sodium anode, which can durably improve the sodium dendrites, contact voids, and charge localization at the interface between the SSE and the anode. Ultimately, the Na3Zr2Si2PO12‐based symmetric cells assembled with reconstructed sodium‐metal anodes can be cycled for more than 1000 h at a current density of 0.3 mA cm−2, which is much higher than the 10 h of commercial sodium‐metal anodes. SSSBs assembled with a Na3V2(PO4)3 cathode exhibit a capacity retention of 89% after 2000 cycles at a 2 C rate. Importantly, the proposed anode reconstruction strategy—which employs a uniformly distributed sodophilic phase to simultaneously mitigate interfacial contact loss and inhibit dendrite formation—establishes a promising pathway toward practical SSSBs.