Chitosan and chitosan oligosaccharide: Advanced carbon sources are used for preparation of N-doped carbon-coated Li2ZnTi3O8 anode material

Abstract

Novel N-doped carbon coated Li2ZnTi3O8 anode active materials are synthesized via one step high temperature calcination solid state reaction method using chitosan and chitosan oligosaccharide as advanced carbon sources. Coating a nano-thickness conductive N-doped carbon layer between particles is beneficial to enhance the electronic transmission speed. Physical characterization results show that all as-prepared samples have a cubic spinel structure with a P4332 space group without any impurities, and the Li2ZnTi3O8 with chitosan additive (molecular weight: 5000) has the best dispersity and smallest particle size in all as-prepared electrode materials. The length of organic compound molecular chain has a direct impact on the agglomeration of particles and reversible lithium intercalation capacity. When tested as the anode for lithium ion batteries, the optimal electrode material shows the largest discharge capacities and remarkable long-term cycling stability at a current density of 1.0, 2.0, and 5.0 A g−1 over 500 cycles, respectively. Combining structural characterization with electrochemical performance, N-doped carbon layer, high degree of particle dispersibility and larger interface contact area are contributed to the enhancement of both electronic and ionic conductivities and of Li2ZnTi3O8.