A novel scalable synthesis of high-rate performance silicon anode materials by liquid-phase coating doping method

• The electrical conductivity of P-doped Si is increased for 5 × 10 3 times. • P-doped Si shows better electrochemical performance, especially the rate performance. • P-doped Si eases volume expansion effect because of higher Li + diffusion coefficient. • Liquid-phase coating phosphorus doping method is novelly used in silicon powders. Recycled solar grade p-type silicon (Si) broken wafers (1–10 Ω·cm) were milled to Si powders, and then doped with phosphoric acid to make n-type Si powders with extremely high conductivity for being used as anode materials for lithium ion batteries. The electrical conductivity of as-obtained phosphorus-doped (P-doped) Si powders is as high as 5263.18 μs/cm, which is nearly 5 × 10 3 times higher than undoped Si (1.04 μs/cm). The charge specific capacity of P-doped Si holds 1920.3 mAhg −1 after 50 cycles at 0.84 A g −1 , when the charge current density increased to 21 A g −1 (only take 12 min for charging), it still maintains at 1758.5 mAhg −1 after 50 cycles. This proves the outstanding cycle stability of P-doped Si at high rate, which can be attributed to the improved conductivity and lithium ion diffusion coefficient. For practical application in full cells, P-doped Si was composited with artificial graphite to be used as the anode, and the cathode adopted was commercial LiNi 0.5 Co 0.2 Mn 0.3 O 2 , which also discloses excellent long cycle stability with a high capacity retention of 80.7% even after 700 cycles at 0.5C (1C = 420 mA g −1 ).