自生长镍基MOF材料的结构调控及其电化学性能

以六水合氯化镍(NiCl2·6H2O)为金属盐,对苯二甲酸(PTA)为有机配体,通过改变溶剂的类型,采用一步溶剂热法在泡沫镍表面自生长高负载量的镍基MOF材料(Ni-MOF/NF)。溶剂对PTA的溶解性越好或pH值越高,PTA在溶液中的去质子速率越快,材料的形核速率越快。自生长镍基MOF材料在不同溶剂体系下表现出球簇、片状和块体状三类形貌,同时负载量也随之改变。当采用三元混合溶剂(N,N-二甲基甲酰胺、水和乙醇的体积比为1∶1∶1)时,Ni-MOF/NF材料在泡沫镍表面的负载量达到10 mg·cm-2,在3 mol·L-1 KOH电解液中1 mA·cm-2的电流密度下的面积容量达到8780 mF·cm-2。在5 mA·cm-2电流密度下,面积容量仍达到5544 mF·cm-2,容量保持率为63%,表现出优良的倍率性能。经过1000次充放电循环后容量保持率为56%,具有良好的循环稳定性能。

Structural Regulation and Electrochemical Performance of Self-Supported Nickel-Based MOF on Ni Foam

We synthesized self-supported Ni-based MOF material on nickel foam (Ni-MOF/NF) with high mass loading vis a one-step hydrothermal method by the use of nickel chloride as a metal salt and terephthalic acid (PTA) as an organic ligand. Solvents had a remarkable effect on the morphology and electrochemical performance of the Ni-MOF/NF because of the different pH values and solubility of PTA. The higher the solubility of the solvent and pH value was, the faster the diproton rate of PTA in the solution and the nucleation rate. As a result, self-supported Ni-based MOF material exhibited different morphologies such as spherical cluster, flake and bulk, resulting in an increasing mass loading of Ni-based MOFs on the Ni foam. When using a ternary mixture (N,N-dimethylformamide, water and ethanol with volume ratio of 1:1:1) solvent, Ni-MOF/NF achieved the highest loading mass of 10 mg·cm^-2 and the area capacity of 8 780 mF·cm^-2 at a current density of 1 mA·cm^-2 in 3 mol·L^-1 KOH electrolyte. Even at high current density of 5 mA·cm^-2, the area capacity still reached at 5 544 mF·cm^-2 and the capacity retention rate was 63%, delivering an excellent rate performance. Furthermore, the area capacity retention rate was 56% after 1 000 cycles.