In-situ synthesized cathode prelithiation additive to compensate initial capacity loss for lithium ion batteries

In order to further improve the energy density and cycle life of lithium-ion batteries, it is very important to develop a prelithiation additive with high capacity and almost no side effects. Unfortunately, most of prelithiation additives usually produce inert residues or gas release after lithium removal, resulting in a negative impact on the electrochemical performance of the electrode. Here, LixCrSSe (0 < x ≤ 4, LiCrSSe, Cr, Li2S and Li2Se mixture) layer was in-situ synthesized as a prelithiation additive with a maximum capacity of 555 mAh/g to make up for the initial capacity loss of lithium ion batteries. CrSSe was found to be the conversion product after nano LixCrSSe electrochemically react with lithium according to X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) data. The specific charge capacity of LiFePO4-Li3.3CrSSe||C full cells is 187 mAh/g, which is 19 mAh/g higher than that of LiFePO4||C full cells. CrSSe as the residue has little effect on the impedance change of LiFePO4 electrode during the cycle. Our results have demonstrated that the in-situ synthesized LixCrSSe is an effective cathode prelithiation additive.