NEGATIVE ELECTRODE MATERIAL, NEGATIVE ELECTRODE ACTIVE MATERIAL, NEGATIVE ELECTRODE FOR LITHIUM ION BATTERY, AND LITHIUM ION BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a negative electrode material for a lithium ion battery having excellent preservation characteristics while providing an average layer surface space of a (002) plane that is larger than that of a graphite material.SOLUTION: A negative electrode material is provided for a lithium ion battery, and an average layer surface space dof a (002) plane that is calculated by an X-ray diffraction method using a CuKα ray as a radiation source is 0.340 nm or more. A chemical adsorbed water ratio A calculated by the following procedures is 0.5% or less. (1) The negative electrode material according to this embodiment is held for 120 hours under a condition that a temperature is 40°C and a relative humidity is 90%RH. (2) (A) a step of holding the negative electrode material for one hour under a condition at a temperature of 130°C and in a nitrogen atmosphere, and (B) a step of raising a temperature of the negative electrode material after the step (A) from 40°C to 540°C at 10°C/minute under the nitrogen atmosphere to measure a weight reduction amount of the negative electrode material, are sequentially performed by using a thermogravimetry measurement device to calculate the chemical adsorbed water ratio A from the following formula. The chemical adsorbed water ratio A[%]=100×(Y-Y)/X where X represents a weight of the negative electrode material after the step (A), and Yrepresents a weight of the negative electrode material at 150°C at the step (B), and Yrepresents a weight of the negative electrode material at 250°C at the step (B).