A method for dynamic characterization of an electrochemical system (such as a lithium-ion battery) is provided, comprising exciting an electrochemical system with a plurality of double-pulse sequences, each comprising a constant-current discharge pulse, a constant-current charge pulse having the same pulse width and pulse amplitude, and a zero-current period between the pulses; and calculating an impulse response, using a recursive or matrix-based method, to dynamically characterize the electrochemical system. A constant state-of-charge is maintained in the electrochemical system. Therefore the signal-to-noise ratio is high due to the repetition of the driving sequence. This method may be employed for on-line determination of the impedance spectrum of an electrochemical system, since the cycling profile can be easily integrated into charge/discharge profiles. Batteries (and other devices) can be diagnosed at high speed and with high accuracy. The double-pulse sequence is robust for fairly noisy systems.