Negative electrode material for lithium ion secondary batteries, and method for evaluating same
AssigneeNEC Corporation
InventorsRyota YUGE, Akio TODA, Takashi MIYAZAKI
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Abstract
There is provided a negative electrode material for lithium ion secondary batteries having a structure in which in charged and discharged states, a LixSi compound (2) exists in the inside of a Li oxide (1) and the LixSi compound is dispersed in the inside of the Li oxide. The negative electrode material, in which volume change resulting from charge/discharge is suppressed, has excellent performance as a negative electrode material for lithium ion secondary batteries.
Claims10
A negative electrode material for lithium ion secondary batteries, comprising a structure in which, in charged and discharged states, a LixSi compound exists in the inside of a Li oxide and the LixSi compound is dispersed in the inside of the Li oxide.
A method for producing a negative electrode material for lithium ion secondary batteries, comprising the steps of:
- heat-treating silicon oxide at 700 to 1100° C. under an inert gas atmosphere or a hydrogen atmosphere to form a structure, in which silicon particles are dispersed in silicon oxide;
- and
- charging the heat-treated silicon oxide used as the negative electrode in the presence of lithium ions to produce a negative electrode having a structure in which, in charged and discharged states, a LixSi compound exists in the inside of a Li oxide and the LixSi compound is dispersed in the inside of the Li oxide.
A method for evaluating a negative electrode material for lithium ion secondary batteries, wherein the material has a structure in which, in charged and discharged states, a LixSi compound exists in the inside of a Li oxide and the LixSi compound is dispersed in the inside of the Li oxide,
- the method comprising measuring at least one of the size, density and inter-particle distance of the LixSi compound within the Li oxide using a small angle X-ray scattering method in charged and discharged states of the negative electrode material to evaluate battery performance.
Dependencies are inferred from the claim text.