Investigation of Carbon-coating Effect on the Electrochemical Performance of LiCoPO₄ Single Particle

抄録

The effect of carbon-coating on the electrochemical properties of LiCoPO₄ was investigated by single particle measurement. For this analysis, micrometer-scale LiCoPO₄ particles with and without carbon-coating were synthesized by hydrothermal method (LiCoPO₄/C0 with 0.3 wt%, LiCoPO₄/C1 with 0.8 wt%, LiCoPO₄/C2 with 1.7 wt% carbon-coating and pristine LiCoPO₄). In the electrochemical tests using the conventional composite electrodes, all the samples showed the similar electrochemical properties with potential plateaus at ∼4.7 V vs. Li/Li⁺. In contrast, single particle measurement showed clear differences in the charge and discharge curves. The pristine LiCoPO₄ showed the potential plateau only in the discharge curve due to a large overpotential of charging. LiCoPO₄/C0 also showed large overpotential. On the other hand, good electrochemical responses were obtained for the LiCoPO₄/C1 and LiCoPO₄/C2 particle electrodes even though their carbon-coating amounts were different. This result suggests that 0.8 wt% or higher carbon-coating enables to improve the electrochemical performance of one particle of LiCoPO₄.