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.