X-ray Absorption Spectroscopic Study of LiCoO2 as the Negative Electrode of Lithium-Ion Batteries

Lithium cobalt oxide (LiCoO2) particles are modified using rotor blade grinding and re‐annealing and used as the active electrode material versus lithium in the 3–0 V potential interval, in which a maximum capacity of 903 mA h g−1 is achieved. X‐ray absorption near edge structure spectra reveal the complete reduction of Co3+ to Co metal at 0 V. Cell recharge leads to an incomplete reoxidation of cobalt. A maximum reversible capacity of 812 mA h g−1 is obtained, although a poor capacity retention upon prolonged cycling may limit its application. Positively different: Lithium cobalt oxide, a widely used positive electrode material in lithium‐ion cells, is studied here as the negative electrode. The changes in the oxidation state and local environment of the cobalt atoms are resolved by using X‐ray absorption spectroscopy (see figure). The formation of cobalt nanoparticles by electrochemical reduction is unfolded.