An end cover assembly, a battery, and an electric device are provided. The end cover assembly is applied to a battery and includes an end cover, a breather valve, and a protective patch. The end cover has a first side facing inside of the battery and a second side opposite the first side and includes a first channel in communication with the first side and the second side. The breather valve includes a gas-permeable membrane in gas communication with the first channel. The gas-permeable membrane includes a gas-permeable portion opened towards the second side of the end cover. The protective patch is provided on the second side of the end cover and covers the gas-permeable portion. The battery includes the end cover assembly. The electric device includes the battery.