The effect of carbon morphology on the LiCoO2 cathode of lithium ion batteries

•The physicochemical characteristics of carbon affect the composite structure.•Graphite provides a homogeneous mixture with LiCoO2.•A thin coating layer of graphite is formed on LiCoO2 particles.•The mechanical milling process is different depending on the type of carbon.•The composite structure relies on the type of carbon in the mechanical milling.

Conductive carbon coatings on cathode materials play a critical role in the electrochemical performance of lithium ion batteries due to the increased electronic conductivity and the protective effect of the organic electrolyte on the cathode material. The composite structure of a cathode depends on the physicochemical properties of the carbonaceous materials. We investigated several types of carbonaceous materials in LiCoO2 electrodes. Platelet-shaped graphite provided superior cyclic voltammograms and specific capacities of the LiCoO2 electrodes compared to nanosized spherical carbon black. The platelet-shaped graphite mixed homogeneously with LiCoO2 and coated on LiCoO2 particles in the form of a thin layer via the ball-milling method. However, the nano-carbon black is dense and aggregates during the ball-milling process. The thick coating of nano-carbon black on the LiCoO2 particles, which were observed in backscattered electron images collected during the SEM measurements, made the penetration of the liquid electrolyte through this thick carbon layer difficult.

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