Abstract
Li2MTi3O8 (M=Co, Co0.5Cu0.5) spinels were successfully synthesized by a simple high temperature solid-state method. Both Li2CoTi3O8 and Li2Co0.5Cu0.5Ti3O8 show a cubic structure with P4332 space group. Rietveld refinement result reveals that Li2CoTi3O8 can be described as [Li0.5Co0.45]tet[(Li0.5Co0.05)Ti1.5]octO4. After Cu2+ doping, half Co2+ in [Li0.5Co0.45]tet[(Li0.5Co0.05)Ti1.5]octO4 is replaced by Cu2+ to form a complex spinel titanate [Li0.5Co0.225Cu0.225]tet[(Li0.5Co0.025Cu0.025)Ti1.5]octO4 without structural changes. As lithium storage material, Li2CoTi3O8 shows poor electrochemical performance at a current density of 100mAg−1 in the potential window of 0.0–3.0V. After 50 cycles, Li2CoTi3O8 maintains a reversible capacity of 42mAhg−1 with a low capacity retention of 19.5%. For comparison, Li2Co0.5Cu0.5Ti3O8 can deliver a higher reversible capacity of 98mAhg−1 after 50 cycles with a capacity retention of 44.4%. It suggests that copper ion doing can effectively enhance the capability for electrochemical lithium storage in Li2CoTi3O8.