Simultaneously enhancing the electronic and ionic conductivities of Li2ZnTi3O8 via modification with polyacrylonitrile-derived carbon for high-performance anodes

Abstract

Polyacrylonitrile (PAN) with CN bonds can be converted to nitrogen-doped carbon during carbonization, which enhances electronic conductivity by compensating for the deficiency of the Li₂ZnTi₃O₈ (LZTO) anode. In this study, LZTO was modified by carbonizing a homogeneous PAN/LZTO powder mixture at approximately 800 ℃ for 5 h in nitrogen stream to uniformly coat nitrogen-doped carbon around the LZTO particles and to yield nitrogen-doped LZTO. PAN-60 exhibited a capacity retention of 74.8% as the current density increased from 0.1 to 1.6 A g⁻¹, and had charge/discharge capacities of 250.1/250.8 mAh g⁻¹ even after 1100 cycles at 0.5 A g⁻¹. Structural and compositional analysis along with electrochemical tests showed that the uniform nitrogen-doped carbon coating and the nitrogen-doped LZTO favor electron transfer, while the defects induced by nitrogen-doping in LZTO promote Li-ion migration. The enhanced electronic and ionic conductivities are favorable to alleviate the polarization during cycling, and thus are responsible for the optimized performance.