A Three-Dimensional Carbon Framework Constructed by N/S Co-doped Graphene Nanosheets with Expanded Interlayer Spacing Facilitates Potassium Ion Storage
Wenxiu Yang, Jinhui Zhou, Shuo Wang, Zichen Wang, Fan Lv, Wenshu Zhang, Weiyu Zhang, Qiang Sun, Shaojun Guo
Abstract
Carbon nanomaterials show potential in achieving good potassium ion storage; however, the limited interlayer spacing in existing carbon nanomaterials greatly impacts the performance of potassium ion batteries (PIBs). Herein, we report a class of three-dimensional (3D) porous carbon framework materials constructed by S/N co-doping graphene nanosheets (CFM-SNG) with an ultralarge interlayer spacing (0.448 nm) and a rich edge defect as high-performance PIBs anodes. The resulting 3D CFM-SNG material achieves enhanced reversible capacity (348.2 mAh/g at 50 mA/g), cycling performance (188.8 mAh/g at 1000 mA/g after 2000 cycles), and rate capability (204.3 mAh/g at a high current density of 2000 mA/g). Density functional theory calculations further demonstrate that the S/N co-doping and formed edge defects not only favor the interlayer spacing expansion and the adsorption of K+ to the 3D CFM-SNG anode but also prevent variation in volume during the potassiation/depotassiation process.