Electrophoresis study on carbon cloth loaded with LiFePO₄ for integrated flexible cathodes in lithium-ion batteries

The electrophoretic technology was used to prepare carbon cloth loaded with LiFePO₄ integrated cathodes to be used in Li-ion batteries. Carbon cloth served as the negative plate in the electrophoresis tank on which LiFePO₄ powder was dispersed in the electrophoresis solution deposited under a direct current electric field. Button batteries were assembled using LiFePO₄-loaded carbon cloth as the cathode and their electrochemical performance was tested. When the electrophoresis solution was at pH 4 and the electrophoresis duration was 5 min, the areal loading of LiFePO₄ on the carbon cloth reached 9.7 mg cm^–2 and the charge-discharge specific capacity reached 120 mAh g^–1. LiFePO₄ could not be deposited on the carbon cloth if the pH value of the electrophoresis solution was too high or too low. The specific capacity of the battery decreased if the electrophoresis time was more than 5 min. For comparison, carbon cloth loaded with LiNiCoAlO₂ and elemental sulphur was also tested. This confirmed that enhancing the conductivity of the powdered active material deposited on the carbon cloth was the key to improving the comprehensive performance of the battery.

At pH > 4, nearly all hydrogen ions were attached to the LiFePO₄ particles and higher amounts of charged LiFePO₄ were deposited on the carbon cloth. At pH 4, the deposition amount of LiFePO₄ reached its highest at 15 mg and the areal loading reached 9.7 mg cm^–2.