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]O2 and Li[Ni1−x−yCoxAly]O2. 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]O2‐based battery.

Dry Electrode Processing Technology and Binders

“…The dry process electrode has better rate performance than the wet process electrode. As shown in Figure 19 [90], a schematic diagram of the distribution of the conductive agent and binder on the surface of the active material of the SC LFP electrode and the LFP electrode obtained by the PTFE fibrillation method is given. In the dry process, the binder, the active material, and the conductive additives undergo solvent-free mixing, and the absence of an insulating layer around the active material is conducive to the transmission of electrons and ions, resulting in a better rate performance [91].…”

Strategies for Enhancing the Stability of Lithium Metal Anodes in Solid-State Electrolytes

“…Since the commercialization of lithium (Li)-ion batteries (LIBs) in the 1990s, they have been widely applied in various fields, such as small electronic devices, Electric Vehicles (EVs), and Energy Storage Systems (ESSs), owing to their high energy density and stable lifespan [1][2][3][4]. Graphite, which is mainly used as the anode material in current LIBs, demonstrates the reversible intercalation/de-intercalation of Li ions between graphene layers, providing stable charge and discharge cycles.…”

Hierarchical, Porous Microspherical Lithium Iron Phosphate with Nanoparticle Shells for High-Rate Capacity and Stability Cathodes

“…As a clean and renewable energy source, lithium-ion batteries are widely used in the fields of electric vehicles and electric energy storage. − The cathode material determines the performance and cost of the battery. , Compared to layered ternary cathode materials, LiFePO 4 (LFP) cathode materials are widely accepted due to their low cost, high safety, and remarkable cycling performance. − However, the application of LFP has faced bottlenecks in the fields of electric vehicles and energy storage. In the electric vehicle field, LFP is difficult to apply in high-power vehicles due to its low electronic conductivity and poor lithium-ion diffusion kinetics.…”

“…Thickening the electrode and placing more LFP in the same shell can help increase the capacity of the single cell. However, thickening the electrode will greatly reduce the rate performance of the single cell, ,− resulting in a nominal power of only 0.25 P (≈0.25C) for almost all large-capacity cells in the market (1 P is the power value corresponding to the energy release within 1 h and 1C is the current value corresponding to the capacity release within 1 h). In addition, due to the low volumetric energy density of LFP, it is difficult to cram more LFP into the shell.…”