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

Comparison of (BiO)2CO3 to CdCO3 as anode materials is investigated in this paper. Electrochemical results show that both (BiO)2CO3 and CdCO3 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 CdCO3 with Li can be associated with the preliminary formation of Cd and Li2CO3 upon the initial lithiation, and then the final formation of LiCd alloy upon further lithiation. In contrast, the electrochemical reaction of (BiO)2CO3 with Li not only results in the formation of Bi and Li2CO3, but also induces the formation of Li2O. Besides, upon further lithiation, the alloying reaction of Bi with Li is a multi-step process to form LiBi, LixBi, and finally Li3Bi as confirmed by electrochemical behaviors and in-situ XRD technique. Compared with CdCO3, (BiO)2CO3 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)2CO3/C composite can be improved to the value of 297.6 mAh g−1 with a capacity retention of 47.8% after 15 cycles.