Abstract: An electrochemical device includes a positive electrode plate and an electrolytic solution. The electrolytic solution includes a phosphorus additive represented by Formula I: A mass percent of the phosphorus additive represented by Formula I in the electrolytic solution is A %. The electrolytic solution further includes a first additive. The first additive includes at least one of fluoroethylene carbonate or vinylene carbonate. The positive electrode plate includes a positive active material; the positive active material includes an M element; the M element includes at least one of Al, Mg, Ti, or B; a mass percent of the M element in the positive active material is X %; and 0.0001?X/A?40. The electrochemical device is highly stable to thermal shocks.