Full-Cell Presodiation Strategy to Enable High-Performance Na-Ion Batteries

As promising alternatives to lithium-ion batteries, sodium-ion batteries suffer from low coulombic efficiency, which stems from Na-deficiency and unstable interfaces for both cathode and anode materials. Exhibiting a favorable solvation structure, Na-naphthalene/tetrahydropyran (Na-NP/THP) is screened and selected as a full-cell presodiation solution for hard carbon (HC) anodes and a P-2 type Na0.67Fe0.1Al0.1Mn0.8O2 (NFAM) cathode, which are both Na-deficient. Through a wealth of characterizations, it is revealed that the proposed presodiation agent not only boosts the initial coulombic efficiency of both HC and NFAM electrodes effectively, but also facilitates robust solid-electrolyte interphase (SEI) and cathode-electrolyte interphase (CEI) on both electrodes. Consequently, the long-term cycling and rate performance are greatly improved thanks to the stabilized structures of electrode materials. Furthermore, a proof-of-concept NFAM||HC pouch cell based on this presodiation strategy is assembled, showing a high reversible capacity and superior cycling performance. By offering a remedy to a full cell system subjected to severe Na-deficiency, this work conceptually demonstrates a feasible strategy to fully tap the potential of high-energy-density materials in sodium-ion batteries.