Integrated Solid Sodium Metal Battery with Reinforced Polymer Electrolyte and Presodiated 3D InSb@Cu Anode

Solid polymer electrolytes (SPEs) are a promising solution for solid-state sodium metal batteries (SSMBs) due to their molecular tunability, non-leakage properties, and ease of processing, but suffer from low room-temperature (RT) ionic conductivity, poor mechanical strength, and inherent sodium (Na) anode interfacial incompatibility. In this study, an integrated SSMB configuration is introduced by pairing an ultrathin, self-polymerized SPE membrane with the porous 3D InSb@Cu substrate. The Poly(DOL)-based (PDOL) SPE is reinforced by aluminum trifluoromethanesulfonate (Al(CF₃SO₃)₃)-anchored bacterial cellulose (BC), designated as ABC-PDOL, achieving superior mechanical strength (15.21 MPa), high ionic conductivity (1.8×10⁻⁴ S cm⁻¹ at 30 °C), and enhanced Na⁺ transference (0.67). Additionally, the InSb@Cu substrate provides abundant Na–In/Na–Sb sodiophilic sites, enabling dendrite-free Na deposition up to 6 mAh cm⁻² and interfacial compatibility with ABC–PDOL electrolyte even under a high current density of 1.4 mA cm⁻². When assembled into a layer-stacked pouch cell, the 3D Na-InSb@Cu|ABC–PDOL|Na₃V₂(PO₄)₃ configuration demonstrates robust cycling stability within a wide temperature range (25–80 °C) as well as the rate behavior up to 5 C. Operando XRD-EIS-DRT characterization further confirms the reversible lattice evolution of the cathode and enhanced Na⁺ diffusion kinetics at the 3D alloy/SPE interface, highlighting the feasibility of the proposed SSMB design.