Comparison of (BiO)2CO3 to CdCO3 as anode materials for lithium-ion batteries

Comparison of (BiO) 2 CO 3 to CdCO 3 as anode materials is investigated in this paper. Electrochemical results show that both (BiO) 2 CO 3 and CdCO 3 are electrochemically active materials with high initial capacities of 1080.1 and 1251.1   mAh   g −1 , respectively. Ex-situ X-ray diffraction (XRD) results show that the electrochemical reaction mechanisms of CdCO 3 with Li can be associated with the preliminary formation of Cd and Li 2 CO 3 upon the initial lithiation, and then the final formation of LiCd alloy upon further lithiation. In contrast, the electrochemical reaction of (BiO) 2 CO 3 with Li not only results in the formation of Bi and Li 2 CO 3 , but also induces the formation of Li 2 O. Besides, upon further lithiation, the alloying reaction of Bi with Li is a multi-step process to form LiBi, Li x Bi, and finally Li 3 Bi as confirmed by electrochemical behaviors and in-situ XRD technique. Compared with CdCO 3 , (BiO) 2 CO 3 can exhibit better electrochemical properties with a reversible capacity of 155.1   mAh   g −1 and a capacity retention of 28.3% after 15 cycles. By introducing carbon black as conductive additive and volume change buffer, the reversible capacity of ball-milled (BiO) 2 CO 3 /C composite can be improved to the value of 297.6   mAh   g −1 with a capacity retention of 47.8% after 15 cycles.