Fang Lingzhe, Xu Jing, Sun Shuo, Lin Baowei, Guo Qiubo, Luo Da, Xia Hui
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology, Nanjing, 210094, China.
Small. 2019 Mar;15(10):e1804806. doi: 10.1002/smll.201804806. Epub 2019 Feb 5.
Anodes involving conversion and alloying reaction mechanisms are attractive for potassium-ion batteries (PIBs) due to their high theoretical capacities. However, serious volume change and metal aggregation upon potassiation/depotassiation usually cause poor electrochemical performance. Herein, few-layered SnS nanosheets supported on reduced graphene oxide (SnS @rGO) are fabricated and investigated as anode material for PIBs, showing high specific capacity (448 mAh g at 0.05 A g ), high rate capability (247 mAh g at 1 A g ), and improved cycle performance (73% capacity retention after 300 cycles). In this composite electrode, SnS nanosheets undergo sequential conversion (SnS to Sn) and alloying (Sn to K Sn , KSn) reactions during potassiation/depotassiation, giving rise to a high specific capacity. Meanwhile, the hybrid ultrathin nanosheets enable fast K storage kinetics and excellent structure integrity because of fast electron/ionic transportation, surface capacitive-dominated charge storage mechanism, and effective accommodation for volume variation. This work demonstrates that K storage performance of alloy and conversion-based anodes can be remarkably promoted by subtle structure engineering.
由于具有较高的理论容量，涉及转化和合金化反应机制的阳极材料对于钾离子电池（PIB）具有吸引力。然而，在钾化/脱钾过程中严重的体积变化和金属聚集通常会导致较差的电化学性能。在此，制备了负载在还原氧化石墨烯上的少层SnS纳米片（SnS@rGO）并将其作为PIB的阳极材料进行研究，其显示出高比容量（在0.05 A g时为448 mAh g）、高倍率性能（在1 A g时为247 mAh g）以及改善的循环性能（300次循环后容量保持率为73%）。在这种复合电极中，SnS纳米片在钾化/脱钾过程中经历连续的转化（SnS到Sn）和合金化（Sn到KSn、KSn）反应，从而产生高比容量。同时，由于快速的电子/离子传输、表面电容主导的电荷存储机制以及对体积变化的有效容纳，这种混合超薄纳米片实现了快速的钾存储动力学和优异的结构完整性。这项工作表明，通过精细的结构工程可以显著提高基于合金和转化的阳极的钾存储性能。
