SnSe Encapsulated in N-Doped Graphitic Carbon Prepared by Cation 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 mAh 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 425 mAh 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 mAh g-1 after 100 cycles at 0.5 A g-1 and a capacity of 165.6 mAh 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-1anode. These results highlight the potential of SnSe@NGC-1 as a promising anode material for PIBs.