Lithium iron phosphate battery with volume energy density up to 560Wh/L developed by the University of California
Update：9/27/2022 3:02:43 PM View : 1925
(LiFePO4, LPF) is widely used as a low-cost cathode material for lithium ion batteries, but low ionic conductivity and electronic conductivity limit its multiplying performance. A lot of efforts have been made to overcome this limitation, such as coating LFP with carbon, mixing LFP with conductive agent and reducing particle size of LFP. These methods improve conductivity and shorten ion diffusion length. However, this carbon coating is usually amorphous and its conductivity is significantly lower than that of graphite. At the same time, the electrode is usually made of a mixture containing LFP particles, adhesives and conductive agents, which are closely contacted to form a conductive network. Excessively reducing the size of LFP particles will reduce the compaction density and may generate more interface contacts, which will increase the interface resistance and destroy the overall conductivity.
Recently, Li Shen, Runwei Mo and Yunfeng Lu from UCLA published their latest research results on Nano Letters, reporting the synthesis of lithium iron phosphate/graphite composites, in which lithium iron phosphate nanoparticles grow in graphite matrix. Graphite matrix has the characteristics of porous, high conductivity and high mechanical strength, and the prepared electrode has excellent cycle performance and magnification performance. This research provides a new strategy for low cost, long life and high power batteries.
Research Highlights
(1) LFP particles were embedded into the graphite layers to obtain a high-performance lithium cathode material;
(2) LFP/graphite composites have high conductivity, low interface resistance and porous structure;
(3) The volume energy density of the electrode made of LFP/graphite composite at 10C and 60C is 560W h L − 1 and 427 W h L − 1, respectively, which is significantly superior to commercial lithium iron phosphate.
1. Preparation of LFP/graphite composite
Figure 1a shows the synthesis process of LFP/graphite composite. First, FeCl3 was embedded into natural graphite by molten salt method, and then solvothermal reaction was carried out in ethylene glycol containing lithium and phosphate to form LFP particles in the graphite layer. Further annealing at high temperature resulted in nano LFP particles embedded in micron sized graphite particles.
As shown in Fig. 1b, the formation of nano LFP minimizes the ion diffusion length in particles, embeds LFP nanoparticles in continuous graphite sheets, minimizes their interface resistance, and generates porous structures during the formation of LFP, allowing effective transmission of electrolytes.
Recently, Li Shen, Runwei Mo and Yunfeng Lu from UCLA published their latest research results on Nano Letters, reporting the synthesis of lithium iron phosphate/graphite composites, in which lithium iron phosphate nanoparticles grow in graphite matrix. Graphite matrix has the characteristics of porous, high conductivity and high mechanical strength, and the prepared electrode has excellent cycle performance and magnification performance. This research provides a new strategy for low cost, long life and high power batteries.
Research Highlights
(1) LFP particles were embedded into the graphite layers to obtain a high-performance lithium cathode material;
(2) LFP/graphite composites have high conductivity, low interface resistance and porous structure;
(3) The volume energy density of the electrode made of LFP/graphite composite at 10C and 60C is 560W h L − 1 and 427 W h L − 1, respectively, which is significantly superior to commercial lithium iron phosphate.
1. Preparation of LFP/graphite composite
Figure 1a shows the synthesis process of LFP/graphite composite. First, FeCl3 was embedded into natural graphite by molten salt method, and then solvothermal reaction was carried out in ethylene glycol containing lithium and phosphate to form LFP particles in the graphite layer. Further annealing at high temperature resulted in nano LFP particles embedded in micron sized graphite particles.
As shown in Fig. 1b, the formation of nano LFP minimizes the ion diffusion length in particles, embeds LFP nanoparticles in continuous graphite sheets, minimizes their interface resistance, and generates porous structures during the formation of LFP, allowing effective transmission of electrolytes.