Non-Selective Suppression of Cation and Anion Crosstalk from an Anode Perspective

Metal fluoride and sulfur cathodes are appealing for their abundance and high capacity but are plagued by severe electrode crosstalk. This occurs when transition metal cations or polysulfide anions dissolve and shuttle to the anode, causing corrosion and rapid capacity fade. Herein, we propose an anode-centric mechanism utilizing a Na-rich nanoalloy (Na_xSn) anode that achieves simultaneous kinetic regulation and physical shielding, suppressing cation and anion crosstalk at both the source and destination. The ultrafast kinetics of the Na_xSn alloy elevate the Damköhler number (Da), a descriptor quantifying the competition between conversion and diffusion, thereby ensuring these species are rapidly reduced at the cathode prior to outward diffusion. Concurrently, this nanoalloy induces the formation of an ultrathin, robust Na₂O-rich solid electrolyte interphase that non-selectively blocks residual cation and anion crossovers. This mechanism enables an FeF₂||Na_xSn full cell to achieve a Coulombic efficiency of 99.93% over 200 cycles. Additionally, the S/C||Na_xSn system supports extreme rate capabilities (630 mAh g^-1 at 20C) and transitions to practical pouch cell configurations, yielding an excellent capacity retention of 91.95% after 1000 cycles at 0.5C. Ultimately, Na-rich nanoalloy anodes offer a compelling pathway toward high-energy, sustainable batteries by transforming electrode crosstalk into a spatiotemporally synergistic anode-cathode coupling.