Biomass-Derived P/N-Co-Doped Carbon Nanosheets Encapsulate Cu3P Nanoparticles as High-Performance Anode Materials for Sodium–Ion Batteries
Yanyou Yin, Yu Zhang, Nannan Liu, Bing Sun, Naiqing Zhang
Abstract
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-codoped carbon nanosheets encapsulating Cu3P nanoparticles (Cu3P@P/N-C) by a feasible aqueous reaction followed by a phosphorization procedure using sodium alginate as biomass carbon source. Cu-alginate hydrogel balls can be squeezed into 2D nanosheets through freeze-drying process. Then Cu3P@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 Cu3P nanoparticles during the continuous charge and discharge process. In addition, the 2D P/N-codoped carbon nanosheets also can 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, Cu3P@P/N-C demonstrated an outstanding reversible capacity of 209.3 mA h g−1 at 1 A g−1 after 1000 cycles. Besides, it still maintained a superior specific capacity of 118.2 mA h g−1 after 2000 cycles, even at a high current density of 5 A g−1.