| The microstructure and electrochemical properties of a Si70Mn30 alloy prepared by melt spinning and arc melting have been investigated. Melt-spun ribbons and arc-melted ingots were fragmented and mixed with acetylene black (AB), polyvinylidene fluoride (PVDF), and N-methylpyrrolidinone by planetary milling for 2 h to characterize their electrochemical properties. The results showed that the microstructures of the melt-spun ribbons represented a fine eutectic constituent composed of a silicon phase with a thickness of approximately 50~70 nm and a Mn4Si7 compound. The cyclic behavior of the rapidly solidified melt-spun Si70Mn30 ribbons improved remarkably over that of the arc-melted specimens because of a finer microstructural scale; as the thickness of silicon crystal decreased 40 fold, the initial irreversible capacity was reduced by more than 2.5 times. The improved cycle performance of the melt-spun ribbons is a consequence of the small diffusion distance for the lithium-ion exchange. |
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