Lithium ion secondary battery active material, lithium ion secondary battery electrode, lithium ion secondary battery, electronic device, electric power tool, electric vehicle, and power storage system

An electrode for lithium ion secondary batteries, the electrode comprising an active material capable of storing and releasing lithium ions and satisfying the following conditions (A) to (D):

• (A) the active material being a Li complex oxide or a Li complex oxoacid salt that contains lithium, oxygen, and at least one of the elements of Groups 2 to 15 of the long-form periodic table;
• (B) the active material containing a plurality of primary particles having a particle size distribution (median diameter:
• nm) with 1 m<D10<65 nm, 5 nm<D50<75 nm, and 50 nm<D90<100 nm;
• (C) the active material having a plurality of pores between the plurality of primary particles, wherein the maximum peak pore size A (nm) in a pore size distribution as measured by a mercury intrusion technique is 10 nm≦A≦75 nm;
• and
• (D) the ratio B/A of the maximum peak pore size A (nm) and the crystallite size B (nm) determined from the half width of the X-ray diffraction pattern of the active material as measured by X-ray diffractometry is 0.5<B/A≦1.

An active material for lithium ion secondary batteries, the active material capable of storing and releasing lithium ions and satisfying the following conditions (A) to (D):

• (A) the active material being a Li complex oxide or a Li complex oxoacid salt that contains lithium, oxygen, and at least one of the elements of Groups 2 to 15 of the long-form periodic table;
• (B) the active material containing a plurality of primary particles having a particle size distribution (median diameter:
• nm) with 1 nm<D10<65 nm, 5 nm<D50<75 nm, and 50 nm<D90<100 nm;
• (C) the active material having a plurality of pores between the plurality of primary particles, wherein the maximum peak pore size A (nm) in a pore size distribution as measured by a mercury intrusion technique is 10 nm≦A≦75 nm;
• and
• (D) the ratio B/A of the maximum peak pore size A (nm) and the crystallite size B (nm) determined from the half width of the X-ray diffraction pattern of the active material as measured by X-ray diffractometry is 0.5<B/A≦1.