Lithium-Ion-Transfer Kinetics of Single LiFePO 4 Particles.

The Li-ion desertion process of a single LiFePO4 particle with a diameter of 400 nm in aqueous media at high potential is investigated by stochastic collision of the particle at a microelectrode. No extra additive, such as polymeric binder or conductive carbon, is involved in this stochastic measurement. The ion diffusion inside the particle is proved to be the rate-determining step that limits the discharge rate of batteries using LiFePO4 in an aqueous environment. This result offers guidance for exploring the most effective enhancement of Li-ion batteries. Moreover, this general method can be applied to study the electrochemical behavior of other electrode materials as an alternative and complementary route.