Large Particle LiFePO4for High Energy Applications
Authors: Syed Moarij , Obrovac Mark 
Published: December 2024

Lithium-ion batteries (LIBs) are the primary sources of power for electric vehicles (EVs), consumer electronics, and grid storage applications.1 However, the widespread usage of LIBs in sectors like EVs and grid storage still presents challenges in terms of cost reduction, minimized environmental impact, and enhanced sustainability. In order to tackle the issue of high cost and increased environmental impact, there is significant emphasis on olivine structured LiFePO4 (LFP) over other common cathode chemistries (i.e., NMC, LCO & LNO) because of its lower cost and environmental friendliness resulting from the abundance of iron.2,3 LFP also possesses desirable properties including high thermal stability and cycle life. Nevertheless, in comparison to layered oxides, LFP materials faces issues of poor electronic conductivity and low Li+ ion diffusion, which have been mitigated through the reduction of particle sizes to submicron (500-800 nm) and the implementation of carbon coating methods.4,5

Recently, we have made notable progress in enhancing the energy density LFP based cathodes.6 This accomplishment was achieved by combining mechanofusion processing and impact milling to consolidate submicron particles into ~10 μm dense flakes using a dry process known as dry particle flaking (DPF). In this presentation, DPF processing will be further demonstrated. Dense ~10 μm LFP/C flake composites with a high packing fraction and a low surface area will be described that; allow ultra high density (UHD) electrodes to be fabricated with electrode press densities exceeding 3.0 g/cm3. These electrodes are fabricated with high loadings (17 mg/cm2) and electrode formulations comprising 96% LFP active material. This corresponds to an electrode porosity of just 8%, resulting in a remarkable 44% increase in volumetric energy density compared to conventional LFP with electrode formulations consisting of 90% active material, as shown in Figure 1(a). In addition, as shown in Figure 1(b), improved cycling retention was observed for UHD LFP coatings compared to conventional LFP with identical columbic efficiency. Moreover, voltage polarization is also reduced for UHD LFP coatings compared to conventional LFP, as shown in Figure 1(c). The capability to manufacture immensely dense LFP electrodes could have significant implications, as it enables the production of cost-effective and environmentally friendly Li-ion cells, while achieving high volumetric energy densities approaching that of Li-ion cells employing layered oxide cathodes.

References
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Figure 1