Yin Yanyou, Zhang Yu, Liu Nannan, Sun Bing, Zhang Naiqing
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China.
Faculty of Science, Center for Clean Energy Technology, School of Mathematical and Physical Science, University of Technology Sydney, Sydney, NSW, Australia.
Front Chem. 2020 May 5;8:316. doi: 10.3389/fchem.2020.00316. eCollection 2020.
Biomass-derived approaches have been accepted as a practical way for the design of transitional metal phosphides confined by carbon matrix (TMPs@C) as energy storage materials. Herein, we successfully synthesize P/N-co-doped carbon nanosheets encapsulating CuP nanoparticles (CuP@P/N-C) by a feasible aqueous reaction followed by a phosphorization procedure using sodium alginate as the biomass carbon source. Cu-alginate hydrogel balls can be squeezed into two-dimensional (2D) nanosheets through a freeze-drying process. Then, CuP@P/N-C was obtained after the phosphorization procedure. This rationally designed structure not only improved the kinetics of ion/electron transportation but also buffered the volume expansion of CuP nanoparticles during the continuous charge and discharge processes. In addition, the 2D P/N co-doped carbon nanosheets can also serve as a conductive matrix, which can enhance the electronic conductivity of the whole electrode as well as provide rapid channels for electron/ion diffusion. Thus, when applied as anode materials for sodium-ion batteries, it exhibited remarkable cycling stability and rate performance. Prominently, CuP@P/N-C demonstrated an outstanding reversible capacity of 209.3 mAh g at 1 A g after 1,000 cycles. Besides, it still maintained a superior specific capacity of 118.2 mAh g after 2,000 cycles, even at a high current density of 5 A g.
生物质衍生方法已被公认为是设计碳基受限过渡金属磷化物（TMPs@C）作为储能材料的一种实用方法。在此，我们通过一种可行的水相反应，然后以海藻酸钠作为生物质碳源进行磷化过程，成功合成了包裹着CuP纳米颗粒的P/N共掺杂碳纳米片（CuP@P/N-C）。通过冷冻干燥过程，铜 - 海藻酸盐水凝胶球可以被挤压成二维（2D）纳米片。然后，经过磷化过程后得到CuP@P/N-C。这种合理设计的结构不仅改善了离子/电子传输动力学，还缓冲了CuP纳米颗粒在连续充放电过程中的体积膨胀。此外，二维P/N共掺杂碳纳米片还可以作为导电基质，提高整个电极的电子导电性，并为电子/离子扩散提供快速通道。因此，当用作钠离子电池的负极材料时，它表现出显著的循环稳定性和倍率性能。值得注意的是，CuP@P/N-C在1 A g下经过1000次循环后，展现出209.3 mAh g的出色可逆容量。此外，即使在5 A g的高电流密度下，经过2000次循环后，它仍保持118.2 mAh g的优异比容量。
