Nano-scale uniform distribution of Ge/Cu3Ge phase and its electrochemical performance for lithium-ion batteries
Electrochimica Acta(2010)
摘要
A germanium/copper germanide/carbon (Ge/Cu3Ge/C) composite is prepared by the Pechini method using GeO2, CuSO4, and citric acid/ethylene glycol as the Ge, Cu and carbon sources, respectively. The microstructure and electrochemical properties of this nano-composite are compared to those of germanium/carbon (Ge/C) that is prepared without the copper precursor. In the latter composite, irregular-shaped submicron-sized (0.4–0.5μm) Ge particles are dispersed inside a carbon matrix. In the former, however, sphere-shaped nano-sized (<100nm) Ge particles are produced, inside of which a Cu3Ge phase is uniformly dispersed in nano-scale. The pure Ge component in both electrodes is lithiated up to Li15Ge4 after a lithiation down to 0.0V at a current density of 100mAg−1. The Cu3Ge-containing electrode gives a superior cycle and rate performance to that of the Cu3Ge-free counterpart. This difference has been ascribed to the favorable roles provided by the nano-sized Cu3Ge phase that is intimately contacted with the nano-sized Ge particles within a sphere. The electrochemical dilatometry study reveals that the electrode swelling is much smaller for the Cu3Ge-containing electrode, illustrating that the electrochemically inactive Cu3Ge phase serves as a buffer against a massive volume change encountered in the Ge component.
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关键词
Lithium-ion batteries,Pechini method,Germanium (Ge) electrodes,Copper germanide (Cu3Ge),Nano-composites,Electrochemical dilatometry
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