NEGATIVE ELECTRODE MATERIAL FOR LITHIUM SECONDARY BATTERY, LITHIUM SECONDARY BATTERY USING THE SAME, AND NEGATIVE ELECTRODE MATERIAL MANUFCTURING METHOD

摘要

PROBLEM TO BE SOLVED: To restrict a volume change of the Fe-Si group compound particle when occluding or discharging lithium ions, and to maintain lithium ion occlusion quantity and lithium ion discharge quantity by the Fe-Si group compound particles even if the number of repetition of occlusion and discharge of the lithium ions increases.

SOLUTION: This negative electrode material is composed of the Fe-Si group compound particles 11 mainly composed of multi-crystal particles 12 formed from a multi-phase multi-crystal body of α-FeSi212a and β-FeSi212b or single phase multi-crystal body of β-FeSi2. The Fe-Si group compound particle 11 has any one or both of a Si group membrane 12c for coating a part or the whole of a surface of the multi-crystal particle 12 with Si or SiO2and a Si atom forming solid solution inside a crystal particle of the multi-crystal particles. Furthermore, the Fe-Si group compound particle is a compound expressed with an expression FeSi2+x(0.01≤x≤4.0).

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