In situ electrochemical studies for Li ⁺ ions dissociation from the LiCoO ₂ electrode by the substrate-generation/tip-collection mode in SECM

This work presents the transportation of Li ⁺ ions at the interface of a charging LiCoO ₂ electrode through the substrate-generation/tip-collection (SG/TC) feedback mode of scanning electrochemical microscopy (SECM). The TC current, due to the reduction of the ethylene carbonate (EC) supermolecule, is collected more strongly at 1.8 V than that of the Li ⁺(DEC) _n at 2.5 V near at the substrate because of the increased concentration of the supermolecule Li ⁺(EC) _m, which means that the electrolyte is not uniformly distributed over the substrate. The smooth SG/TC current loop is formed at the probe position optimized by the probe scan curve technique between the LiCoO ₂ substrate with 4.0 V and the probe with 1.8 V, which is applied to analyze the Li ⁺ ion transport at the interface of the LiCoO ₂ electrode. Moreover, the LiCoO2 substrate, which has a flat surface, is imaged to the nonuniform surface electrochemically by the SECM. We infer that these experimental techniques will help analyze transporting Li ⁺ ions at the interface and the electrochemical uniformity of the electrode.