Effect of back-side-coated electrodes on electrochemical performances of lithium-ion batteries

In order to investigate the effect of back-side coating of cathodes and anodes upon electrochemical performances of lithium-ion batteries (LIBs), four different pouch-type lithium cobalt oxide (LiCoO₂, LCO)/graphite unit cells with different coating conditions are prepared and compared in a systematic manner. Their electrochemical performance, in terms of Coulombic efficiency, capacity realization, capacity retention ability, and rate capabilities, is investigated. From the results, we confirm an opposing relationship existing between back-side-coated cathodes and anodes, in that the coated cathodes provide improved cell performance, while the coated anodes impede it. This is attributed to the fact that, as is generally understood, cathodes act as noble lithium (Li) ion suppliers for LIBs, while anodes consume a large portion of Li ions to form surface layers during the first charging process. Furthermore, we also confirm that the magnitude of the back-side coating effect for LCO and graphite are somewhat different. The double-side-coated cathodes have a notable positive effect on cell performances in contrast to the negative effect seen with the double-side-coated anodes. As a result, unit cells employing double-side-coated cathodes with single-side-coated anodes show the best performance, followed by those based on double-side-coated cathodes with double-side-coated anodes rather than single-side-coated cathodes with single-side coated anodes.