CPC H01M 4/525 (2013.01) [C01G 51/66 (2013.01); C01G 53/66 (2013.01); H01M 10/0525 (2013.01); C01P 2002/32 (2013.01); C01P 2002/52 (2013.01); C01P 2002/72 (2013.01); C01P 2002/77 (2013.01); C01P 2002/85 (2013.01); C01P 2002/88 (2013.01); C01P 2004/04 (2013.01); C01P 2006/40 (2013.01); C01P 2006/42 (2013.01); H01M 2004/028 (2013.01)] | 5 Claims |
1. A lithium ion secondary battery comprising:
a positive electrode active material comprising lithium cobalt oxide,
wherein a dQ/dV vs V curve in a range of greater than or equal to 4.0V and less than or equal to 4.8V is obtained by differentiating capacitance (Q) with respect to voltage (V) in a charge curve,
wherein the dQ/dV vs V curve comprises both a first peak and a second peak in a range of greater than or equal to 4.0V and less than or equal to 4.2V,
wherein the positive electrode active material has a crystal structure with a space group of P2/m between the first peak and the second peak,
wherein the dQ/dV vs V curve comprises a third peak in a range of greater than or equal to 4.5V and less than or equal to 4.7V, and
wherein a height of the third peak is less than a height of each of the first peak and the second peak.
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