Electrochemical Kinetics and Safety of 2-Volt Class Li-Ion Battery System Using Lithium Titanium Oxide Anode

Microvoltammograms of a single particle of lithium titanium oxide (LTO, Li4/3Ti5/3O4) spinel were interpreted using a core-shell model in the spinel/rock-salt two-phase transition process. Lithium insertion into the particle was controlled by the diffusion in LTO rock-salt structure outlayer. The quick charging was effectively enhanced by reducing the LTO particle size. Lithium extraction from the particle was significantly affected by the charge transfer on the LTO spinel outlayer rather than by the diffusion of lithium ions. The discharge speed during the internal short-circuit abuse test connecting with the LTO anode was 3 orders of magnitude slower than that with graphite anode. At the internal short-circuit point, transformation to the low electron-conductive LTO spinel phase will work to suppress the rapid extension of internal short circuit reaction. A 2 V class lithium-ion battery system using the LTO anode had a high output and input power density of 4000 W/kg for a 10 s pulse condition. Quick-charging performance showed 80% of the full capacity in 1 min. It was demonstrated that the 2 V class lithium-ion battery system exhibited excellent high power and quick charging with outstanding safety characteristics by using the LTO anode.