Electrode, secondary battery, battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus

An electrode comprising

• an active material layer on a current collector, wherein:
• the active material layer includes spherical secondary active material particles each comprising a plurality of first primary particles and planular secondary active material particles each comprising a plurality of second primary particles,
• the spherical secondary active material particles are each included in a first region of the cathode active material layer, and the planular secondary active material particles are each included in a second region of the cathode active material layer that is farther from the current collector than the first region,
• the first primary particles have an average particle diameter that is larger than an average particle diameter of the second primary particles, and
• the spherical secondary active material particles have an average degree of circularity that is larger than an average degree of circularity of the planular secondary active material particles.

A battery pack comprising:

• a secondary battery;
• a control section controlling a used state of the secondary battery;
• and
• a switch section switching the used state of the secondary battery according to an instruction of the control section, wherein:
• the secondary battery includes:
• a cathode including a cathode active material layer on a cathode current collector,
• an anode, and
• an electrolytic solution,
• the cathode active material layer includes spherical secondary active material particles each comprising a plurality of first primary particles and planular secondary active material particles each comprising a plurality of second primary particles,
• the spherical secondary active material particles are each included in a first region of the cathode active material layer, and the planular secondary active material particles are each included in a second region of the cathode active material layer that is farther from the cathode current collector than the first region,
• the first primary particles have an average particle diameter that is larger than an average particle diameter of the second primary particles, and
• the spherical secondary active material particles have an average degree of circularity is larger than an average degree of circularity of the planular secondary active material particles.