The application relates to the technical field of batteries, and provides an electrochemical device, which comprises a positive
electrode sheet, a negative
electrode sheet and a separator, the negative
electrode sheet comprises a negative electrode
current collector and a negative electrode
active layer located on at least one side surface of the negative electrode
current collector, the negative electrode
active layer comprises a negative electrode active material, the negative electrode active material comprises a
silicon-based material; the separator comprises a base film and a
ceramic layer arranged on at least one side surface of the base film, the
ceramic layer comprises a plurality of interval distributed stripes and a plurality of interval areas located in the middle of adjacent stripes, the width of the stripe is A1 mu.m, and the width of the interval area is A2 mu.m; the electrochemical device satisfies the relationship formula 0.06 <= A * C <= 0.9, wherein A is A1 / A2, and C is the
mass content of
silicon elements in the negative electrode active material. The scheme effectively alleviates the
volume expansion of the
silicon negative electrode, improves the charging and discharging efficiency, reduces the minimum residual
power level capable of effective discharging, and improves the available
discharge depth.