Preparation of novel composites based on SDS intercalated CoNiFe-LDH and carbon materials for advanced asymmetric supercapacitors

Herein, three novel composites (CB/CoNiFe(SDS)-LDH, CNTs/CoNiFe(SDS)-LDH and CNFs/CoNiFe(SDS)-LDH) with high specific capacity and high retention were prepared by combining SDS intercalated CoNiFe-LDH with various carbon materials. The addition of SDS improved the layer spacing and induced the LDH nanosheets to form porous flower-like structures. This structure had more electrochemically active sites and facilitated charge/ electrolyte ion transfer, resulting in a higher specific capacity of the material. The addition of carbon materials enhanced the overall electrical conductivity of the material, resulting in further performance improvements. Among the composites, CNFs/CoNiFe(SDS)-LDH exhibited exceptionally excellent electrochemical properties (203.3 mAh g(-1) at 1 A g(-1) and 71.3 % 1-30 A g(-1)). Then, asymmetric supercapacitors (ASCs) based on the composites and activated carbon (AC) were assembled. Compared to CB/CoNiFe(SDS)-LDH//AC and CNTs/ CoNiFe(SDS)-LDH//AC ASCs, CNFs/CoNiFe(SDS)-LDH//AC ASC had larger specific capacitance (148.1 F g(-1) at 1 A g(-1)) and higher capacitance retention (56.2 %, 1-15 A g(-1)). After 10,000 cycles at 10 A g(-1), the capacitance retention of the CNFs/CoNiFe(SDS)-LDH//AC, CB/CoNiFe(SDS)-LDH//AC and CNTs/CoNiFe(SDS)LDH//AC ASCs were 85.0 %, 75.3 % and 85.2 %, showing good application prospects.