Realization of Sn₂P₂S₆-carbon nanotube anode with high K⁺/Na⁺ storage performance via rational interface manipulation–induced shuttle-effect inhibition and self-healing

Because the electrochemical performance of next-generation batteries is strongly affected by the electronic properties of their electrode materials, it is highly desirable to find ways to easily tune these properties. In this study, we synthesized a Mott–Schottky-type Sn₂P₂S₆-carbon nanotube heterojunction with many heterointerfaces and accelerated interfacial electron/ion transfer as the anode material for K-ion batteries (KIBs) and Na-ion batteries (NIBs). The constructive built-in electric fields directly affect the quality and composition of the solid-electrolyte interphase, preventing the entrapment of K⁺/Na⁺ ions inside the electrode during charging, the abnormal aggregation and coarsening of Sn nanoparticles, polyphosphide and polysulfide shuttling, and the accumulation of detrimental intermediate phases. Moreover, SnPS₃ nanocrystals experience reversible self-healing and regeneration during long-lasting recharge reactions. In the KIBs, the composite delivers an initial discharge capacity of 930 mAh g⁻¹ (at 0.05 A g⁻¹) and approximately 100% capacity retention at 1 A g⁻¹ after 600 cycles; in the NIBs, the composite delivers an initial discharge capacity of 1400 mAh g⁻¹ (at 0.1 A g⁻¹) and an 80.62% retention at 1 A g⁻¹ after 600 cycles. The concept implemented for the construction of heterostructures with regulated electronic band structures can be used to exploit the electrochemical properties of other emerging electrode materials.