Ultrafine 3D Nanoporous Carbon Coated Multicomponent Sulfide Heterojunction for Enhanced Na Ion Storage
Naixuan Ci, Xianke Yue, Jun Miao, Boxuan Cao, Xuanyan Wang, Jingchen He, X.A. Wang, Xun Yi, Yinghe Zhang, Kolan Madhav Reddy, Hua‐Jun Qiu
Abstract
Abstract Transition metal sulfides are promising sodium‐ion battery anodes. Herein, a multicomponent MnNiFe‐based sulfide heterojunction with ultrafine nanoporous structure and inherent 3D carbon coating is synthesized using commercially available MnNiFeCO 3 as the precursor. It is found that the multicomponent metal interaction greatly inhibits the surface diffusion during carbonate decomposition process, resulting in ultrafine nanoporous MnNi(Fe)O 3 (≤ 10 nm) with a much larger surface area when compared with a single metal‐based counterpart. To enhance the conductivity and structure stability of the heterojunction, a thin layer of N, S‐doped 3D porous carbon is inherently coated on the nanoporous MnNiFeS x (NS‐C@MnNiFeS) by first forming a 3D polyaniline layer on the nanoporous MnNi(Fe)O 3 , which is then transformed into doped carbon during the vulcanization process. Owing to the multicomponent heterojunction design (which may provide more active sites for effective Na + adsorption), much increased specific surface area, and 3D inherent carbon coating, the NS‐C@MnNiFeS exhibits significantly enhanced performance for Na + storage. After 90 cycles at 0.1 A g −1 , a record‐high reversible capacity of 859.2 mAh g −1 is achieved, and it can be stably cycled for 1500 cycles at a current density of 10.0 A g −1 . DFT calculation reveals the modified electronic structure and enhanced Na + adsorption by constructing the heterojunction.