Improving ZnSe anode by Ti3C2Tx and in-situ formed carbon for high-performance lithium-ion capacitors

The electrochemical performances of lithium-ion capacitors (LICs) are severely hindered by the mismatch in reaction kinetics between the anode and cathode. Herein, to enhance the anode conductivity and improve the Li + ion diffusion rate for better kinetic matching, Ti 3 C 2 T x (MXene) sheets, known for their high electrical conductivity and excellent mechanical properties, were selected as a support for ZnSe. Simultaneously, the carbonization of hexadecyl trimethyl ammonium bromide reactant generated a carbon coating on the ZnSe surface. The results indicate that Ti 3 C 2 T x and the in-situ generated carbon reduce the aggregation of ZnSe particles, leading to the formation of ZnSe/Ti 3 C 2 T x /C composite with a large specific surface area of 46.5 m 2 g –1 . The synergistic effect of Ti 3 C 2 T x and carbon enhances the Li + ion storage performance of the ZnSe anode, achieving a remarkable reversible discharge specific capacity of 1006.3 mAh g –1 after 450 cycles at 0.2 A g –1 , along with improved Li + ion transfer capability. Ethylene glycol-reduced graphene oxide (EG-RGO) was also prepared; it has a large average discharge specific capacity of 84.7 mAh g –1 at 0.1 A g –1 . An optimized ZnSe/Ti 3 C 2 T x /C//EG-RGO LIC achieves a prominent energy density of 119.4–34.5 Wh kg –1 at a power density of 156.8–15525.0 W kg −1 , along with an impressive cycling span, retaining 84.1 % of its capacity after 5000-cycle test at 0.5 A g –1 .