Boosting NH ₄ ⁺ adsorption of Ti ₃ C ₂ T _<i>x</i> @S‐V ₂ O ₅ @CNF nanofiber by S doping and heterostructure construction: local charge regulation

Abstract Aqueous ammonium ion battery (AAIB) is considered as a promising candidate for next‐generation energy storage device, while the limited performance of cathode material retards its further development. Seeking novel materials and reveal the underlying energy storage reinforcement mechanism is necessary for promoting future commercial application of AAIB. Herein, a novel electrospun Ti 3 C 2 T x @S‐V 2 O 5 @CNF nanofiber is constructed by sulfur doping and Ti 3 C 2 T x introduction strategy to exert the synergetic effect on NH 4 + storage capacity. Density functional theory calculations indicate that the induction of Ti 3 C 2 T x can redistribute the internal charges of material, induce the downshift of the d‐band center of V atoms and p‐band center of S atoms to the Fermi level, thus the adsorption energy of NH 4 + is optimized. Electrochemical results show that the Ti 3 C 2 T x @S‐V 2 O 5 @CNF electrode displays high capacity of 576.2 mAh g −1 at 0.5 A g −1 , long cycle life and superior rate performance. The assembled Ti 3 C 2 T x @S‐V 2 O 5 @CNF//PTCDI full cell also exhibits excellent electrochemical behavior including large specific capacity of 181 mAh g −1 at 0.5 A g −1 , cycling stability of 10,000 cycles at 5 A g −1 with no capacity decay, and good rate performance. This work gives insight into the NH 4 + storage capacity control by rational local charge regulation through S doping and heterostructure construction to facilitate electron transfer for AAIBs and other energy storage system.