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. 2024 Jan 9;36(2):803-814.
doi: 10.1021/acs.chemmater.3c02301. eCollection 2024 Jan 23.

High Energy Density Large Particle LiFePO4

Moarij A Syed  1 , M Salehabadi  1 , M N Obrovac  1   2
Affiliations

High Energy Density Large Particle LiFePO4

Moarij A Syed et al. Chem Mater. .

Abstract

To improve the energy density of LiFePO4 (LFP) cathode materials for Li-ion cells, we have utilized a modified mechanofusion method for preparing micrometer-sized LFP/C composite flake particles. The resulting flake particle morphology resulted in improved packing efficiency, enabling an electrode porosity of 14% to be achieved at high loadings, which represents a volumetric energy density increase of 28% compared to conventional LFP. Furthermore, LFP/C flake composites electrodes were found to have a higher coulombic efficiency, a reduced voltage-polarization, and a greatly reduced charge transfer resistance compared to conventional LFP electrodes. This is believed to be due to the low surface area of the LFP/C flake composite particles coupled to fast Li+ ion grain boundary diffusion. The ability to make highly dense LFP and low surface area electrodes could have profound impacts, allowing for Li-ion cells to be made with low cost and low environmental impact LFP, while high achieving volumetric energy densities and high coulombic efficiencies.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Schematic diagram of the DPF process.
Figure 2
Figure 2
SEM images of (a) LFP starting material, (b) graphite feedstock particles, (c) 50 μm ZrO2 template particles, (d) coated LFP/C template particles following mechanofusion, (e) coated LFP/C template particles and free composite flakes following impact milling, (f) unheated LFP/C composite flakes, and (g) heated LFP/C composite flakes.
Figure 3
Figure 3
SEM images of (a) LFP, (b) F-LFP0, (c) F-LFP2, and (d) F-LFP5.
Figure 4
Figure 4
XRD patterns of (a) a hand-mixed LFP–graphite mixture used as a control sample, (b) F-LFP2 flake composite materials following DPF processing, and (c) F-LFP2 flake composite materials after heating.
Figure 5
Figure 5
Particle cross sections of a single F-LFP2 particle utilizing a focused gallium-ion beam (FIB) showing (a) a top-down view of a particle etched by an FIB directed at the top of the particle and (b) a view perpendicular to the basal plane of a particle that was cross-sectioned by a FIB.
Figure 6
Figure 6
Galvanostatic cycling results of LFP and F-LFP flake composites with varying graphite content. (a)Voltage–capacity profiles. (b) Reversible capacity and CE. (c) Polarization versus cycle number.
Figure 7
Figure 7
Rate capability of LFP, F-LFP2, and F-LFP5 uncalendered electrodes at varying rates.
Figure 8
Figure 8
Nyquist plots of symmetric cells with LFP, F-LFP2, and F-LFP5 uncalendered electrodes. The plots were fit by using the equivalent circuit shown.
Figure 9
Figure 9
Electrode cross sections of (a) LFP[31P] electrode and (b) F-LFP2[14P] electrode.
Figure 10
Figure 10
(a) Voltage–capacity profiles of calendered LFP[31P] and F-LFP2[14P] electrodes. (b) Reversible capacity and CE. (c) Polarization with respect to cycle number of calendered LFP[31P] and F-LFP2[14P] electrodes.
Figure 11
Figure 11
Nyquist plots of symmetric cells with LFP[14P] and F-LFP2[31P calendered electrodes.
See this image and copyright information in PMC

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