Abstract
Abstract Representative Ge-rich binary Co–Ge compounds (CoGe, Co5Ge7, and CoGe2) are synthesized by facile solid-state reactions and apply as Li-ion battery (LIB) anode materials. Among the binary Co–Ge compounds studied, CoGe2 shows the highest Li reversibility. Thus, a CoGe2-decorated carbon composite (CoGe2@C) is prepared to improve the electrochemical performance of CoGe2. Ex situ analysis results of X-ray diffraction and extended X-ray absorption fine structure demonstrate that the CoGe2@C has an interesting mechanism of conversion/recombination during Li insertion/extraction. Owing to this continual conversion/recombination mechanism during cycling, the CoGe2@C shows superior electrochemical performance. Specifically, CoGe2@C shows high reversible capacity (1,106 and 973 mAh/cm3 at current density of 50 and 100 mA/g, respectively), stable cycling behavior (93.3% and 98.8% capacity retention at a cycling rate of 50 mA/g and 100 mA/g, respectively, after 100 cycling), and fast rate capability with stable cycling behavior (~700 mAh/cm3 at 1C rate over 200 cycles). Therefore, CoGe2@C can be used as a high-performance LIB anode material.
Published Version
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