An energy storage device according to one aspect of the present invention includes: a negative electrode including a negative electrode substrate and a negative active material layer layered directly or indirectly on a surface of the negative electrode substrate; and a positive electrode. The negative active material layer contains a negative active material. The negative active material contains non-graphitizable carbon. In one direction of the negative electrode substrate, at least one end edge side of the negative active material layer is thicker than a central portion present between the one end edge side and the other end edge side facing the one end edge side. When a true density of the non-graphitizable carbon is A [g/cm.sup.3], an amount of charge B [mAh/g] of the negative electrode in a fully charged state satisfies the following formula 1.

[1]$-173\text{XA+1588}\le \text{B}\le \text{-830A+1800}$

An energy storage device according to one aspect of the present invention includes: a negative electrode including a negative electrode substrate and a negative active material layer layered directly or indirectly on a surface of the negative electrode substrate; and a positive electrode. The negative active material layer contains a negative active material. The negative active material contains non-graphitizable carbon. In one direction of the negative electrode substrate, at least one end edge side of the negative active material layer is thicker than a central portion present between the one end edge side and the other end edge side facing the one end edge side. When a true density of the non-graphitizable carbon is A [g/cm.sup.3], an amount of charge B [mAh/g] of the negative electrode in a fully charged state satisfies the following formula 1.

[1]$-173\text{XA+1588}\le \text{B}\le \text{-830A+1800}$

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a lithium-nickel composite oxide. A first O1s spectrum, a second O1s spectrum, a b1s spectrum, a S2p spectrum, a F1s spectrum, and a Ni3p spectrum are detectable by a surface analysis of the positive electrode by X-ray photoelectron spectroscopy. The first O1s spectrum has a peak within a range of binding energy that is greater than or equal to 528 eV and less than or equal to 531 eV. The second O1s spectrum has a peak within a range of binding energy that is greater than 531 eV and less than or equal to 535 eV.

A negative electrode material for a secondary battery includes a matrix containing silicon oxide, a composite oxide of one or more doping elements selected from an alkali metal, an alkaline earth metal, and a post-transition metal, and silicon, or a mixture thereof; and silicon nanoparticles dispersed and embedded in the matrix.

Provided in the present disclosure are a positive electrode material used for a lithium ion battery. The positive electrode material comprises substrate particles, a first cladding layer that covers the substrate particles, and a second cladding layer that covers the first cladding layer; the substrate particles contain LiNi.sub.xMn.sub.y Co.sub.zM.sub.1-x-y-zO.sub.2; the first cladding layer contains lithium cobalt oxide; and the second cladding layer contains an oxide of a transition metal.

A secondary battery according to an embodiment of the present disclosure is a secondary battery including a cathode in which a cathode material is applied onto a cathode current collector, wherein the cathode material includes an irreversible additive and a cathode active material, and the irreversible additive includes lithium nickel oxide (LNO) having a trigonal crystal structure within an operating range from 3.0 V or more to 4.0 V or less in the secondary battery.

A secondary battery according to an embodiment of the present disclosure is a secondary battery including a cathode in which a cathode material is applied onto a cathode current collector, wherein the cathode material includes an irreversible additive and a cathode active material, and the irreversible additive includes lithium nickel oxide (LNO) having a trigonal crystal structure within an operating range from 3.0 V or more to 4.0 V or less in the secondary battery.

A negative electrode for a lithium metal battery includes a metal current collector substrate. A lithium metal layer is formed on at least one surface of the metal current collector substrate. A pre-lithiation layer is formed on the lithium metal layer. The pre-lithiation layer includes a prelithiated active material.

The use of a blend of a lithium nickel oxide and a lithium manganese iron phosphate as an active material composition in the cathode of a lithium secondary electrochemical cell for automotive applications, such as hybrid and electric vehicles. This blend allows decreasing the porosity of a lithium manganese iron phosphate-based cathode. It also allows improving the detectability of a gas release in the cell in case of an abnormal operation of the cell. It allows lowering the cell impedance at a low state of charge, typically less than 30%, and reducing the impedance increase of the cell during the cell lifespan.

The present invention provides an active electrode material comprising a mixture of (a) at least one niobium oxide and (b) at least one mixed niobium oxide; wherein the mixed niobium oxide has the composition M1.sub.aM2.sub.1-aM3.sub.bNb.sub.12-bO.sub.33-c-dQ.sub.d, wherein: M1 and M2 are different; M1 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi and mixtures thereof; M2 is Mo or W; M3 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≤a<0.5; 0≤b≤2; −0.5≤c≤1.65; 0≤d≤1.65; one or more of a, b, c and d does not equal zero; and when a, b, and d equal zero, c is greater than zero. Such materials are of interest as active electrode materials in lithium-ion or sodium-ion batteries.