Dual Polymer/Liquid Electrolyte with BaTiO₃ Electrode for Magnesium Batteries

With a low cost and high volumetric capacity, rechargeable magnesium batteries (RMBs) have emerged as promising candidates for post-lithium ion batteries. The kinetically sluggish Mg2+ insertion/extraction in the host lattice and the anode/electrolyte incompatibility render the battery irreversible in some instances and restrict the commercial applications. In this work, we replace the conventional electrolyte with a dual layer of liquid and polymer electrolyte onto the cathode and anode, respectively, and investigate the structural, electrical, and electrochemical properties. It exhibits a remarkable Mg-ion conductivity up to 4.62 × 10–4 S cm–1 at 55 °C, a high transfer number (tMg2+ = 0.74), low overpotential, and relatively stable Mg stripping and plating during the initial cycles. Furthermore, this work uses an unconventional electrode, BaTiO3 (BTO), to demonstrate the performance of Mg batteries and track the structural and electrochemical changes. The quasi-solid-state Mg batteries fabricated with premagnesiation and thermally treated BTO cathode materials show good electrochemical performance. The approaches herein may provide new directions for exploiting high-performance Mg batteries through the perovskite structure cathode and functional dual electrolyte.