Secondary battery, battery pack, vehicle, and stationary power supply

A secondary battery, comprising:

• an aqueous electrolyte;
• a positive electrode;
• and
• a negative electrode, the negative electrode comprising a negative electrode active material, the negative electrode active material comprising a Ti-containing composite oxide, at least one element A selected from the group consisting of Hg, Pb, Zn, and Bi being present on a surface of the negative electrode, and an average of molar ratios (A/(A+Ti)) of the element A being more than or equal to 5% and less than or equal to 40%, each of the molar ratios being a molar amount of the element A to a sum between the molar amount of the element A and a molar amount of Ti on the surface of the negative electrode, according to scanning electron microscopy-energy dispersive X-ray spectroscopy.