Negative electrode material for lithium-ion secondary cell, method for manufacturing negative electrode material for lithium-ion secondary cell, negative electrode material slurry for lithium-ion secondary cell, negative electrode for lithium-ion secondary cell, and lithium-ion secondary cell
A negative electrode material for a lithium-ion secondary cell, comprising carbon particles having an oxygen content of 0.15% by mass or less.
1. A negative electrode material for a lithium-ion secondary cell, comprising natural graphite particles having an oxygen content of 0.04% by mass or less.
2. The negative electrode material for a lithium-ion secondary cell according to claim 1 , wherein the natural graphite particles have an R value of 0.45 or less.
3. The negative electrode material for a lithium-ion secondary cell according to claim 1 , wherein the natural graphite particles have a rhombohedral crystal amount of greater than 0.20.
4. The negative electrode material for a lithium-ion secondary cell according to claim 1 , wherein the natural graphite particles have a circularity of greater than 0.8.
5. The negative electrode material for a lithium-ion secondary cell according to claim 1 , wherein the natural graphite particles do not have a DTA exothermic peak detected in a range of from 500° C. to 650° C. in differential thermal analysis.
6. The negative electrode material for a lithium-ion secondary cell according to claim 1 , wherein the natural graphite particles have a specific surface area measured by nitrogen gas adsorption of 4.0 m 2 /g or more.
7. A negative electrode material slurry for a lithium-ion secondary cell, comprising the negative electrode material for a lithium-ion secondary cell according to claim 1 , an organic binder, and a solvent.
8. A negative electrode for a lithium-ion secondary cell, comprising a current collector and a negative electrode layer, the negative electrode layer comprising the negative electrode material for a lithium-ion secondary cell according to claim 1 .
9. A lithium-ion secondary cell, comprising a positive electrode, an electrolyte, and the negative electrode for a lithium-ion secondary cell according to claim 8 .
10. A method for manufacturing a negative electrode material for a lithium-ion secondary cell, the method comprising:
a process of heating natural graphite particles until a temperature of the natural graphite particles is from 1000° C. to 1300° ° C.; and
a process of cooling the natural graphite particles after the heating until a temperature of the natural graphite particles is less than 400° C.,
the heating and the cooling being performed in a non-oxidizing atmosphere, respectively.
11. The method for manufacturing a negative electrode material for a lithium-ion secondary cell according to claim 10 , which is a method for manufacturing the negative electrode material for a lithium-ion secondary cell according to claim 1 .