POWER STORAGE ELEMENT

To provide a power storage element in which an electrode is prevented from being bent by pressing.SOLUTION: A power storage element includes an electrode including a foil-shaped electrode base material, and an active material layer superimposed on the electrode base material and containing a particulate active material, and the particle size D50 and the particle size D90 of the active material satisfy a relational expression of 0.39 ≤ particle size D50 / (particle size D50 + particle size D90) ≤ 0.43 (In the formula, the particle size D50 is the particle size at which the volume integration is 50% in the particle size distribution, and the particle size D90 is the particle size at which the volume integration is 90% in the particle size distribution).SELECTED DRAWING: Figure 1 【課題】電極がプレスによって曲がることが抑制された蓄電素子を提供する。【解決手段】箔状の電極基材と、該電極基材に重ねられ且つ粒子状の活物質を含む活物質層と、を有する電極を備え、活物質の粒径Ｄ５０と粒径Ｄ９０とは、０．３９≦粒径Ｄ５０／（粒径Ｄ５０＋粒径Ｄ９０）≦０．４３の関係式を満たす（式中、粒径Ｄ５０は、粒度分布にて体積積算が５０％となる粒径であり、粒径Ｄ９０は、粒度分布にて体積積算が９０％となる粒径である。）、蓄電素子を提供する。【選択図】図１