La~(3+)掺杂NiCo层状双金属氢氧化物纳米片的合成及其电化学性能

稀土离子La~(3+)掺杂的NiCo层状双金属氢氧化物纳米片具有高的超级电容器性能,比容量达到1115 F/g(1A/g)、倍率性能为517 F/g(30 A/g)。研究表明,La~(3+)离子掺杂不改变NiCo层状双金属氢氧化物晶体结构,但会显著影响其电子和离子传导特性,从而改变其电化学性能。根据离子电负性标度,La~(3+)(1.327)和Co~(2+)(1.377)离子的电负性值最接近,掺杂La~(3+)会优先取代Co~(2+)离子位置。由于La~(3+)离子的尺寸作用(106 pm),使得最优掺杂比例较小仅为0.26%,电化学结果表明较少的La~(3+)掺杂比例依然会显著调节NiCo层状双金属氢氧化物的电子/离子输运性质。

La3+-doped NiCo Layered Double Hydroxide Nanosheets and Their Supercapacitive Performance

NiCo layered double hydroxides(NiCo-LDHs) are important electrode materials in batteries and supercapacitors, due to its layered structure and controllable ratio and kind of metal ions. In this paper, we studied the effect of La³⁺ ions on the crystal structures and electrochemical performances of NiCo-LDHs. According to ionic electronegativity, the values of La³⁺(1.327) and Co²⁺(1.377) are similar, leading to the replace of Co²⁺ by La³⁺ in La³⁺-doped NiCo-LDHs. La³⁺-doped NiCo-LDHs show high specific capacitance and rate performance, 1115 F/g at 1 A/g and 517 F/g at 30 A/g, respectively. XRD, FTIR and SEM prove that La³⁺ doping does not change the structures of NiCo-LDHs. However, CV and electrochemical impendence spectrum confirms that the nature of electron or ion transfer is adjusted by La³⁺ doping. Owing to the size effect of La³⁺ ions, the optimized ratio of La doping is 0.26%. La³⁺ ions doping in electrode materials can be a promising method to change their nature of electron or ion transfer(electron or ion conductivity).