First reported by Goodenough in 1997, the application of LiFePO_4 in Li-ion batteries is becoming increasingly important for the battery industry due to the improved safety feature offered by the LiFePO_4 materials. In recent years, intensive efforts have been made by the battery community for the development of a LiFePO_4 cathode battery to satisfy the strict safety requirements for applications such as EV/HEV, power tool, E-bicycle, etc. Binders are used in batteries to keep the electrode particulates in contact with each other (cohesion) and in contact with the current collector (adhesion). The binder solution is usually added to a slurry of other ingredients that is coated on current collectors. Polyvinylidene difluoride (PVDF) polymers are widely used in lithium-ion batteries as binders, especially in cathodes. Due to the small primary particle size of LiFePO_4, it is more difficult to fabricate a LiFePO_4 electrode with good adhesion, cohesion, and mechanical strength relative to regular LiCoC_2 electrodes. In this report, we have investigated the slurry viscosity, electrode adhesion and cell performance with a series of high molecular weight (HMW) PVDF grades in LiFePO_4 cathodes.
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