Dual Functions of Carbon in Li(sub4)Ti(sub5)O(sub12)/C Microspheres

Abstract

Spinel Li(sub4)Ti(sub5)O(sub12) has become an alternative material to replace graphite anodes in terms of solving safety issues and improving battery life-time. Unfortunately, as Li(sub4)Ti(sub5)O(sub12) is an insulator, the low electrical conductivity becomes a major drawback, as it is unfavorable to higher rate capability. In addition to the low electronic conductivity, severe gassing during charge/discharge cycles is a critical but often-overlooked problem of Li(sub4)Ti(sub5)O(sub12) batteries. Li(sub4)Ti(sub5)O(sub12)/C microspheres were prepared by assembling the nano-Li(sub4)Ti(sub5)O(sub12) (50–300 nm) with pitch derived pyrolytic carbon. It was found that the coated carbon in Li(sub4)Ti(sub5)O(sub12)/C microspheres can effectively inhibit gassing and Mn deposition in LiMn(sub2)O(sub4)/Li(sub4)Ti(sub5)O(sub12) battery. Carbon can also significantly improve rate capability and cycling performance compared with that of Li(sub4)Ti(sub5)O(sub12) microspheres without carbon due to stable interface and superior electronic conductivity.