Reconciling Capacity Degradation for Sodium-Ion Pouch Cell by Practical Electrocatalytic-Driven Compensation Strategy

Irreversible active sodium loss (ASL) is widely regarded as a pivotal factor influencing the cycle life and energy density of sodium-ion full cells. Introducing practical electrocatalyst-driven compensation strategies for ASL and other multiple benefits in sodium-ion batteries (SIBs) is a tireless pursuit of researchers. Herein, Pd atoms were used to catalytically drive the decomposition of Na₂O to compensate for ASL in Na₃(Mn_0.8Fe_0.2)₂(PO₄)(P₂O₇)//hard carbon (NMFPP//HC) pouch cells. This compensation strategy not only replenished the sodium inventory loss caused by SEI and Mn²⁺ shuttle effect but also constructed a NaF-rich rigid CEI layer. The dissolution and shuttling of Mn²⁺ can be significantly inhibited by this kind of rigid NaF-CEI layer. Finally, incorporating 8 wt % currently modified precondition with NMFPP cathode, the energy density of the corresponding pouch cell (NMFPP-PNO//HC) presents an essential improvement of 29% relative to the unmodified system. This study proposes a universal approach for ASL compensation and electrode stabilization in the design of high-performance SIBs.