▎ 摘　　要

NOVELTY - Pole piece comprises substrate which includes a current collector (01) and a protective layer (02) disposed on the surface of the current collector. An active material layer (03) is also provided on the protective layer. The protective layer includes an inactive material. The inactive material includes an inorganic material, and satisfies: the content of iron in the inorganic material is less than or equal to 100ppm, the sodium content is less than or equal to 400ppm, the content of potassium is less than or equal to 100ppm, and the content of calcium is less than or equal to 400ppm. USE - The pole piece is useful in electrochemical device (claimed). ADVANTAGE - The pole piece can simultaneously improve the safety and cycle performance of the electrochemical device. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an electrochemical device. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a pole piece structure. Current collector (01) Protective layer (02) Active material layer (03)