Low-Resistance LiFePO4 Thick Film Electrode Processed with Dry Electrode Technology for High-Energy-Density Lithium-Ion Batteries

Abstract

LiFePO4 emerges as a viable alternative to cobalt-containing cathodes, such as Li[Ni1-x-yMnxCoy]O-2 and Li[Ni1-x-yCoxAly]O-2. As Fe is abundant in nature, LiFePO4 is a low-cost material. Moreover, stable structure of LiFePO4 imparts long service life and thermal stability. However, the practical implementation of LiFePO4 cathode in energy storage devices is impeded by its low energy density and high ionic/electrical resistance. Herein, the LiFePO4 electrode with high active material loading and low ionic/electrical resistance through the dry process is reported for the first time. The dry process not only enables the uniform distribution of the polymeric binders and conductive additives within the thick electrode but also inhibits the formation of cracks. Furthermore, the bridge-like connection of polytetrafluoroethylene facilitates the insertion and extraction of Li ions to the LiFePO4 crystal. Hence, the dry-processed LiFePO4 electrode with high areal capacity (7.8 mAh cm(-2)) exhibits excellent cycle stability over 300 cycles in full-cell operation. In addition, it is demonstrated that the estimated energy density of prismatic cell with the dry-processed LiFePO4 electrode is competitive with state-of-the-art Li[Ni1-x-yMnxCoy]O-2-based battery.