An electrical device comprising a power generating element containing: a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on the surface of a positive electrode current collector; a negative electrode in which a negative electrode active material layer containing a negative electrode active material is formed on the surface of a negative electrode current collector; and a separator, wherein the coating amount of the negative electrode active material layer is from 3 to 11 mg/cm 2 , the negative electrode active material layer contains a negative electrode active material represented by the following formula : [Numerical formula 1] α Si-containing alloy + β carbon material in the formula, α and β represent % by weight of each component in the negative electrode active material layer, 80 ≤ α + β ≤ 98, 3 ≤ α ≤ 40, and 40 ≤ β ≤ 95, the positive electrode active material layer contains a positive electrode active material represented by the following formula : [Numerical formula 2] e solid solution positive electrode active material in the formula, e represents % by weight of each component in the positive electrode active material layer, and 80 ≤ e ≤ 98, the solid solution positive electrode active material is represented by the following formula : [Numerical formula 3] Li 1.5 [Ni a Mn b Co c [Li] d ]O z in the formula, z = 3, a + b + c + d = 1.5, 0.1 ≤ d ≤ 0.4, and 1.1 ≤ [a + b + c] ≤ 1.4, and one or more kinds of elements M selected from the group consisting of Nb, Sn, W, Mo, and V are present on particle surfaces of the solid solution positive electrode active material in an amount satisfying 0.002 ≤ [M]/[a + b + c] ≤ 0.05 when a, b, and c are the molar composition ratio in the formula and the molar amount of presence of the element M is represented by [M]. a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on the surface of a positive electrode current collector; a negative electrode in which a negative electrode active material layer containing a negative electrode active material is formed on the surface of a negative electrode current collector; and a separator, wherein the coating amount of the negative electrode active material layer is from 3 to 11 mg/cm 2 , the negative electrode active material layer contains a negative electrode active material represented by the following formula : [Numerical formula 1] α Si-containing alloy + β carbon material in the formula, α and β represent % by weight of each component in the negative electrode active material layer, 80 ≤ α + β ≤ 98, 3 ≤ α ≤ 40, and 40 ≤ β ≤ 95, the positive electrode active material layer contains a positive electrode active material represented by the following formula : [Numerical formula 2] e solid solution positive electrode active material in the formula, e represents % by weight of each component in the positive electrode active material layer, and 80 ≤ e ≤ 98, the solid solution positive electrode active material is represented by the following formula : [Numerical formula 3] Li 1.5 [Ni a Mn b Co c [Li] d ]O z in the formula, z = 3, a + b + c + d = 1.5, 0.1 ≤ d ≤ 0.4, and 1.1 ≤ [a + b + c] ≤ 1.4, and one or more kinds of elements M selected from the group consisting of Nb, Sn, W, Mo, and V are present on particle surfaces of the solid solution positive electrode active material in an amount satisfying 0.002 ≤ [M]/[a + b + c] ≤ 0.05 when a, b, and c are the molar composition ratio in the formula and the molar amount of presence of the element M is represented by [M]. <EOS>