Abstract: The present embodiment provides a lithium ion secondary battery including a positive electrode containing LiaNixCoyMzO2 (0.9?a?1.2, 0.3?x?0.8, 0.2?y+z?0.7, where M is a metal element other than Li, Ni, and Co) as a positive active material, and a negative electrode containing non-graphitic carbon as a negative active material. In this lithium ion secondary battery, at a portion where the positive electrode and the negative electrode face each other, a basis weight (P) of the positive active material and a basis weight (N) of the negative active material satisfy a relational expression of 0.65?P/N?1.05.

Abstract: An energy storage device according to an aspect of the present invention includes: a negative electrode including a negative substrate made of pure aluminum or an aluminum alloy, a conductive layer directly or indirectly layered on the negative substrate and containing a conductive agent, and a negative active material layer containing a negative active material capable of occluding lithium ions at a potential of 0.05 V vs. Li/Li+ or lower; and a positive electrode opposed to the negative electrode and including a positive substrate and a positive active material layer directly or indirectly layered on the positive substrate, and the negative active material layer is layered on the negative substrate and the conductive layer so as to include a region in contact with the negative substrate and a region in contact with the conductive layer.

Abstract: An energy storage device includes a negative electrode having a negative active material layer containing amorphous carbon as an active material, a curve attained by determining a rate of change (dQ/dV) in a potential (V) of the amorphous carbon in a discharge capacity (Q) of the amorphous carbon per unit quantity based on a result attained by measuring the potential (V) with respect to the discharge capacity (Q) and representing the rate of change (dQ/dV) with respect to the potential (V) has one or more peaks in a range in which the potential of the amorphous carbon is 0.8 V or more and 1.5 V or less, and a potential of the negative electrode at time of full charge is 0.25 V or more with respect to a lithium potential.

Abstract: An energy storage device includes a negative electrode having a negative active material layer containing amorphous carbon as an active material, a curve attained by determining a rate of change (dQ/dV) in a potential (V) of the amorphous carbon in a discharge capacity (Q) of the amorphous carbon per unit quantity based on a result attained by measuring the potential (V) with respect to the discharge capacity (Q) and representing the rate of change (dQ/dV) with respect to the potential (V) has one or more peaks in a range in which the potential of the amorphous carbon is 0.8 V or more and 1.5 V or less, and a potential of the negative electrode at time of full charge is 0.25 V or more with respect to a lithium potential.

Abstract: The present embodiment provides a lithium ion secondary battery including a positive electrode containing LiaNixCoyMzO2 (0.9?a?1.2, 0.3?x?0.8, 0.2?y+z?0.7, where M is a metal element other than Li, Ni, and Co) as a positive active material, and a negative electrode containing non-graphitic carbon as a negative active material. In this lithium ion secondary battery, at a portion where the positive electrode and the negative electrode face each other, a basis weight (P) of the positive active material and a basis weight (N) of the negative active material satisfy a relational expression of 0.65?P/N?1.05.