Observably improving initial coulombic efficiency of C/SiO_x anode using-C-O-PO_3Li_2 groups in lithium ion batteries

摘要

To enhance the initial coulombic efficiency of C/SiOx (0 < x <= 2) composites for commercial applications, -O-PO3H2 groups are introduced on the surface of the carbon skeleton of porous carbonized rice husks to synthesize P-doped porous C/SiOx composites through a facile phosphoric acid activation process. The -O-PO3H2 groups can react with electrolyte to form a -C-O-PO3Li2 layer during the first discharge process, which performs the functions as a solid electrolyte interface layer similar to Li3PO4, effectively hindering the formation of a thick solid electrolyte interface layer and thus substantially improving the initial coulombic efficiency of porous C/SiOx electrode. As anode materials of lithium ion batteries, the resulting composites possess a larger specific capacity of 1151.8 mAh g(-1) at 0.1 A g(-1) with an enhanced initial coulombic efficiency of 79.2%, compared with that of pure carbonized rice husks (45.7%). Even at a higher current density of 2 A g(-1), its specific capacity can be maintained at approximately 439.2 mAh g(-1) up to 1023 cycles with a capacity loss of only 0.013% per cycle.