Sr-doped urchin-like NiCo hydroxide and Sr-doped flower-like NiCo hydroxide@O-doped layered porous carbon for high-performance asymmetric supercapacitors with gel electrolyte

MM Wang and KH Han and JH Qi and ZC Teng and JG Zhang, JOURNAL OF CLEANER PRODUCTION, 349, 131161 (2022).

DOI: 10.1016/j.jclepro.2022.131161

In order to improve the engineering practicability and cyclic stability of electrode material, the biomass-based porous carbon is designed as the solid substrate to load the mixed metal hydroxide. O-doped layered porous carbon is prepared from bagasse pith by chemical activation. Its flat and broad surface is ideal for loading metal hydroxide. A simple strategy is devised to synthesize Sr-doped urchin-like NiCo hydroxide (U-SrNiCo-OH) and Sr-doped flower-like NiCo hydroxide@O-doped layered porous carbon (F-SrNiCo-OH@OLPC). The U-SrNiCo-OH electrode shows high specific capacity (616.69 C g(-1) at 1 A g(-1) and 425.00 C g(-1) at 50 A g(-1)) and excellent rate performance (68.92% retention from 1 A g(-1) to 50 A g(-1)). Compared with the U-SrNiCo-OH electrode, the F-SrNiCo- OH@OLPC-40 electrode exhibits close specific capacity (584.16 C g(-1) at 1 A g(-1) and 341.66 C g(-1) at 50 A g(-1)) and higher cyclic stability (63.59% retention after 5000 cycles). When used as the positive material, F-SrNiCo-OH@OLPC-60 performs best. In the gel electrolyte, the asymmetric supercapacitor based on F-SrNiCo-OH@OLPC-60 delivers high specific capacitance (93.60 F g(-1) at 0.5 A g(-1) and 47.00 F g(-1) at 10 A g(-1)) and high energy density (29.12 W h kg(-1) at 374.14 W kg(-1)). Based on the molecular dynamics (MD) simulations, the OLPC configuration with microporous structure similar to that of OLPC is constructed, and the charging dynamics of asymmetric supercapacitor is studied. F-SrNiCo-OH@OLPC, with low cost and excellent electrochemical performance, has great application potential in energy storage/conversion. The MD simulations provide a new perspective for understanding the energy storage process of asymmetric supercapacitor.

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