Affiliation:
1. State Key Laboratory of Chemical Resource Engineering Laboratory of Electrochemical Process and Technology for Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
2. Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Beijing 100029 P. R. China
3. China Academy of Aerospace Science and Innovation Beijing 100081 P. R. China
4. Department of Chemical Engineering and Biotechnology University of Cambridge New Museums Site, Pembroke Street Cambridge CB2 3RA UK
Abstract
AbstractAn efficient method for the synthesis of a self‐supporting carbon framework (denoted Gra‐GC‐MoSe2) is proposed with a triple‐gradient structure—in sodiophilic sites, pore volume, and electrical conductivity—which facilitates the highly efficient regulation of Na deposition. In situ and ex situ measurements, together with theoretical calculations, reveal that the gradient distribution of Se heteroatoms in MoSe2, and its derivatives tailor the sodiophilicity, while the gradient distribution of porous nanostructures homogenizes the Na+ diffusion. Therefore, Na deposition occurs from the bottom to the top of the Gra‐GC‐MoSe2 framework without dendrite formation. In addition, the gradient in electrical conductivity ensures the stripping process does not lead to dead Na. As a result, a Gra‐GC‐MoSe2 modified Na anode (Na@Gra‐GC‐MoSe2) shows impressive cycling stability with a high average Coulombic efficiency in an asymmetric cell. In symmetric cells, it also exhibits a long cycling life of 2000 h with a low polarization voltage and works stably even under a large capacity of 10 mAh cm−2. Moreover, a Na@Gra‐GC‐MoSe2|| Na3V2(PO4)3 full cell delivers a high energy density with an excellent cycling performance.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Beijing Nova Program
Fundamental Research Funds for the Central Universities