Abstract: A method for detecting a state of an energy storage device (e.g. lithium-ion battery) is provided, which includes acquiring at least one of a change signal of a temperature or a change signal of a pressure inside the energy storage device, and determining the state of the energy storage device based thereon. The method may further include triggering a warning when the state of the energy storage device meets a preset condition, such as when the energy storage device is determined to be in an irreversible state, an internal short circuit state, a safety valve opening state, or a thermal runaway state. A detection device implementing the detection method is also provided, which comprises a sensing module and an analyzing module. The sensing module is arranged at an interior position of the energy storage device, and can include an optical sensor and/or an electrical sensor.

Abstract: An in-situ and in-operando internal state detecting system for an energy storage device comprises a first acoustic signal-emitting acoustic signal emission module, an interior-residing optical sensing module, and a first input optical signal-providing signal demodulation module. The optical sensing module receives a second acoustic signal when the first acoustic signal transmits inside the energy storage device, and outputs a first optical signal, which is demodulated and analyzed by the signal demodulation module to obtain acoustic feature information. Optionally, the signal demodulation module also provides a second input optical signal, and the optical sensing module outputs a second optical signal, which is analyzed by the signal demodulation modulation module to obtain optical feature information.