SnSe encapsulated in N-doped graphitic carbon prepared by exchange methods for a high-performance anode in potassium-ion batteries

Abstract

Recently, potassium-ion batteries (PIBs) have attracted significant attention as a promising alternative to lithium-ion batteries due to the natural abundance and cost-effectiveness of potassium. Because graphite has a low theoretical capacity of about 270 mA h g⁻¹ as an anode in PIBs, there is an urgent need to explore novel anode materials with high reversible capacities. Tin selenide emerges as a promising anode with a high theoretical capacity of 847 mA h g⁻¹, non-toxicity, and economic merits. Nonetheless, SnSe suffers from low electrical conductivity and structural instability during cycles. To address this issue, this study introduced N-doped graphitic carbon (NGC) for the first time by using an organic matrix to establish an intimate contact between SnSe particles and NGC. Dopamine was utilized as a carbon and nitrogen source, and it was transformed to NGC by the catalytic graphitization of an in situ formed Ni catalyst. Subsequently, SnSe was synthesized in the NGC matrix via a cation exchange reaction to replace Ni with Sn. The SnSe@NGC-1 electrode exhibited a discharge capacity of 355 mA h g⁻¹ after 100 cycles at 0.5 A g⁻¹ and a capacity of 165.6 mA h g⁻¹ after 5000 cycles at 2 A g⁻¹ with an excellent long-term cycling performance. In addition, the SnSe@NGC-1‖KFe(Fe(CN)₆) full cell exhibited a high energy density of 917.1 Wh kg_anode⁻¹. These results highlight the potential of SnSe@NGC as a promising anode material for PIBs.