Low‐Resistance LiFePO₄Thick Film Electrode Processed with Dry Electrode Technology for High‐Energy‐Density Lithium‐Ion Batteries

Abstract

LiFePO 4 emerges as a viable alternative to cobalt‐containing cathodes, such as Li[Ni 1– x – y Mn x Co y ]O 2 and Li[Ni 1− x − y Co x Al y ]O 2 . As Fe is abundant in nature, LiFePO 4 is a low‐cost material. Moreover, stable structure of LiFePO 4 imparts long service life and thermal stability. However, the practical implementation of LiFePO 4 cathode in energy storage devices is impeded by its low energy density and high ionic/electrical resistance. Herein, the LiFePO 4 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 LiFePO 4 crystal. Hence, the dry‐processed LiFePO 4 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 LiFePO 4 electrode is competitive with state‐of‐the‐art Li[Ni 1– x – y Mn x Co y ]O 2 ‐based battery.