Synthesis of high rate capability N-doped carbon coated on lithium zinc titanate via a surfactant-assisted solid-state route

Abstract

N-doped carbon coated on a Li₂ZnTi₃O₈ (LZTO@C–N) anode has been successfully synthesized via a simple surfactant-assisted solid-state method using Tween 80 as surfactant, gelatin as nitrogen source, gelatin and Tween 80 as composite carbon source, and ammonium oxalate as pore-foaming agent. It is shown that nano-sized LZTO particles (∼30 nm) are coated with a carbon layer. The N-doped carbon greatly benefits the electrochemical performance of LZTO@C–N. The largest capacities of 205.4, 193.1, 174.8 and 164.9 mA h g⁻¹ are delivered at 2, 3, 5 and 6 A g⁻¹, respectively. 193.2, 183.2, 159.6 and 139.9 mA h g⁻¹ are still kept at the 100th cycle, respectively. The good electrochemical performance of the LZTO@C–N electrode at high current densities is due to its large specific surface area and pore size, small particle size, low charge-transfer resistance, high Li⁺ diffusion coefficient and the existence of N-doped carbon.