Long cycle life of carbon coated lithium zinc titanate using copper as conductive additive for lithium ion batteries

High conductivity pristine copper particles and carbon coated Li2ZnTi3O8 composite (Li2ZnTi3O8/C@Cu) is prepared by one-step sol-gel method followed by high temperature pyrolysis. Amorphous carbon coating layer reveals a thickness of 2.0-8.0 nm on the outer surface of Li2ZnTi3O8 active grains, which improves the electronic conductivity and charge transfer rate of primary and secondary particles. Moreover, copper particles between particles could enhance the electronic transmission at large current densities and decrease diffusion resistance. As a result, Li2ZnTi3O8/C@Cu composite shows lower electrochemical polarization and quicker kinetic behavior compared to Li2ZnTi3O8/C. Cycled at 1000 mA g (1), 2000 mA g (1), and 3000 mA g (1), Li2ZnTi3O8/C@ Cu can deliver a reversible capacity of 124.4 mAh g (1), 90.8 mAh g (1), and 79.1 mAh g (1) after 1000 cycles, which is much higher than the values of 70.7 mAh g (1), 75.5 mAh g (1), and 52.1 mAh g (1) obtained by Li2ZnTi3O8/C. In addition to higher specific capacity, electrode polarization and cycle stability have been improved after adding copper particles. The improved electrochemical properties of Li2ZnTi3O8/C@ Cu composite are attributed to the combination of copper additive and carbon layer. (C) 2016 Elsevier Ltd. All rights reserved.