Cooperative interface catalysis and electronic regulation induced by single atomic tin in high-performance potassium-ion batteries

Constructing single atomic metal (SAM) sites in carbon materials is considered an effective strategy to enhance their electrochemical performance in potassium ion batteries (PIBs). However, investigating the interaction between SAM and carbon skeleton, and how SAM improves potassium storage performance, remains crucial and challenging for the design of SAM-based electrode materials. Herein, we report a carbon nanosheet anchored with single-atom tin coordinated by three nitrogen atoms and two oxygen atoms (i.e., Sn₁N₃O₂), which demonstrates a synergistic effect for potassium storage. The Sn₁N₃O₂ site catalyzes anion dissociation in the electrolytes, thereby promoting the formation of an inorganic-rich solid electrolyte interphase layer, which is the key component to enhancing stability. In addition, the single-atom Sn tunes the electronic structure of N and O for appropriate K⁺ adsorption energy and reduces the diffusion barrier. Consequently, the SAM anode exhibits significantly improved capacity, rate capability, and outstanding long-term stability. Even more impressive is that a full PIB cell employing this anode also demonstrates an extremely long service life with 81 % capacity retention after 3000 cycles at 2 A g⁻¹. This work precisely elucidates the role of SAM in enhancing the performance of carbon materials in PIBs.