Faculté des sciences

Impact of composite structure and morphology on electronic and ionic conductivity of carbon contained LiCoO2 cathode

Kwon, Nam Hee ; Yin, Hui ; Brodard, Pierre ; Sugnaux, Claudia ; Fromm, Katharina M.

In: Electrochimica Acta, 2014, vol. 134, p. 215–221

Cathodes in lithium ion batteries consist of an ionic conductor, an electronic conductor and a binder in order to make a composite that is both electronically and ionically conductive. The carbon coating on the cathode material plays a critical role for the electrochemical properties of lithium ion batteries due to the increased electronic conductivity. We explain the relationship between the... More

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    Summary
    Cathodes in lithium ion batteries consist of an ionic conductor, an electronic conductor and a binder in order to make a composite that is both electronically and ionically conductive. The carbon coating on the cathode material plays a critical role for the electrochemical properties of lithium ion batteries due to the increased electronic conductivity. We explain the relationship between the electrochemical properties and the characteristics of composites prepared using the ball-milling process in this report. We investigated two types of carbonaceous materials (graphite and carbon black) in LiCoO₂ electrodes. These selected carbon materials have different characteristics and structure upon ball-milling with LiCoO₂. The composite prepared by ball-milling for 5 min leads to better mixing of carbon and LiCoO₂, an intimate contact of carbon on LiCoO₂, a higher lithium ion diffusion (DLi) than non ball-milled and longer ball-milled composites. On the other hand, a longer time of ball-milling (30 and 60 min) decreases the electronic and ionic conductivity due to an increase of disordered structure of carbon and a thick and dense carbon coating layer on LiCoO₂ particles, preventing the diffusion of lithium ions, respectively.