Indirect oxidation of LiCoO ₂ electrodes: More severe conditions to analyze the interface performance

The transport of electrolyte was characterized by the probe current above the LiCoO ₂ substrate using the probe approach curve (PAC) at a constant probe potential (4.8 V) and linear sweep voltammetry (LSV) at a fixed position from the substrate. The current in the LSV experiment increased as the probe was within 3 μm of the substrate, whereas the current at the PAC decreased significantly. The increase of the probe current in the LSV was induced by the circulation of the redox reactant, PF ₆ ^- ions, which is continuously oxidized at the probe while the oxidized species is reduced at the LiCoO ₂ substrate in the narrow space. This indirect oxidation of the LiCoO ₂ substrate was observed by applying the Probe Generation/Substrate Generation to the Probe Collection (PG/SG→PC) mode, which is more severe than the typical SG/PC mode. Therefore, this approach provides new technology to design an electrolyte for Li ion batteries with high rate performance.