Is Li4Ti5O12 a solid-electrolyte-interphase-free electrode material in Li-ion batteries? Reactivity between Li4Ti5O12 electrode and electrolyte

Abstract: Does Li4Ti5O12 need carbon in lithium-ion battery? We answered to this question in the previous work showing that the partially reduced Ti4+ at the surface of Li4Ti5O12 can provide the necessary electronic conductivity to initiate the electrochemical process. In this work, we are discussing the generally accepted fact that the solid electrolyte interphase (SEI) is hardly formed at the surface of Li4Ti5O12 electrode owing to its high redox potential by using carbon-free Li4Ti5O12 electrode to exclude the influences of carbon. In contrast to the generally accepted fact, Li4Ti5O12 was found to have certain reactivity with electrolyte at room (25 oC) and high temperature (60 oC), respectively. Moreover, under the existence of carbon in the electrode (i.e. the conventional electrode formulation), the reactivity of the electrode with electrolyte was significantly increased at higher temperature. These results were discussed based on surface analyses and electrode morphology observation before and after cycling and correlated to the electrochemical performance of both electrodes.