Li Xudong, Ding Rui, Shi Wei, Xu Qilei, Liu Enhui
Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan, 411105, P. R. China.
Chemistry. 2017 May 17;23(28):6896-6904. doi: 10.1002/chem.201700568. Epub 2017 Apr 20.
Ternary nickel cobalt fluoride (Ni-Co-F) nanocrystals are constructed solvothermally for use as the positive electrode materials in supercapacitors. The optimal Ni-Co-F (Ni/Co=2:1) shows slight chemical shifts in X-ray diffraction (XRD) data and X-ray photoelectron spectra (XPS) compared with bare Ni-F and Co-F. The Ni-Co-F (Ni/Co=2:1) exhibits typical square nanocrystal morphology together with a mesoporous surface structure, as observed through TEM observations and nitrogen sorption measurements. Owing to the stronger synergistic effect of Ni and Co redox species originated from the richer Ni and Co surface electroactive sites, Ni-Co-F (Ni/Co=2:1) shows superior performances of specific capacitance, rate capability, and charge-transfer kinetics (564 F g at 1 Ag , 418 F g at 16 Ag , 449 Ω) compared with all the other Ni-Co-F candidates. Moreover, the activated carbon (AC)//Ni-Co-F (Ni/Co=2:1) asymmetric capacitor designed based on charge balance delivers superior energy and power densities (18.4 Wh kg , 6.64 kW kg ) together with longer cycle life (77 % retention after 10 000 cycles at 4 A g ).
通过溶剂热法制备了三元镍钴氟化物（Ni-Co-F）纳米晶体，用作超级电容器的正极材料。与纯Ni-F和Co-F相比，最佳的Ni-Co-F（Ni/Co = 2:1）在X射线衍射（XRD）数据和X射线光电子能谱（XPS）中显示出轻微的化学位移。通过透射电子显微镜（TEM）观察和氮吸附测量发现，Ni-Co-F（Ni/Co = 2:1）呈现出典型的方形纳米晶体形态以及介孔表面结构。由于来自更丰富的Ni和Co表面电活性位点的Ni和Co氧化还原物种具有更强的协同效应，与所有其他Ni-Co-F候选材料相比，Ni-Co-F（Ni/Co = 2:1）在比电容、倍率性能和电荷转移动力学方面表现出优异的性能（在1 A g时为564 F g，在16 A g时为418 F g，449 Ω）。此外，基于电荷平衡设计的活性炭（AC）//Ni-Co-F（Ni/Co = 2:1）不对称电容器具有优异的能量和功率密度（18.4 Wh kg，6.64 kW kg）以及更长的循环寿命（在4 A g下10000次循环后保持77%）。
