Abstract:

Using a porous electrode theory of LiFePO₄ (LFP) lithium battery discharge behavior were discussed in detail and found with the discharge process and internal electrode electrochemical reaction from diaphragm lateral set side fluid move, and move past LFP basic completion of discharge process, electric cut-off electrochemical reaction stop in a certain position of the electrode, and not all of the LFP particles are completing the discharge. The effects of discharge rate, electrode conductivity and electrolyte diffusion coefficient on the discharge process were studied. With the increase of discharge rate, the distance of the electrochemical reaction is decreased, and the peak value increases, and the peak area becomes narrow. The increase of the polar plate conductivity can ensure that the electrochemical reaction is carried out from the side of the diaphragm, but the increase of the electrode conductivity cannot be further improved by the peak value of the electrochemical reaction to the depth of the electrode. The higher diffusion coefficient can ensure that all the active materials can react with electrochemical reactions. The above conclusions can provide an effective guide for the design and preparation of high performance LFP lithium batteries.

Key words: lithium battery, LFP, discharge