LITHIUM-ION SECONDARY BATTERY

This lithium-ion secondary battery may have a positive electrode, a negative electrode, a separator present between the positive electrode and the negative electrode and an electrolytic solution. The negative electrode may contain silicon or a silicon compound and a binder, and the binder may contain polyimide. When the negative electrode after discharging is observed by nuclear magnetic resonance (NMR) spectroscopy using a single-pulse magic-angle spinning method (SP-MAS method) and peaks are separated by a Gaussian function, a Lorentzian function or a Voigt function, an NMR spectrum of a solid7 Li nucleus may have a first peak, and the first peak may have a peak top in a chemical shift range of 0.5 ppm or more and 1.5 ppm or less with Li in LiCoO2 set to −0.5 ppm.