DC-AC hybrid rapid heating method for lithium-ion batteries at high state of charge operated from low temperatures

Alternating current (AC) preheating strategy for lithium ion batteries (LiBs) at high state of charge (SOC) is prone to exceeding their voltage limit and risking their health. To address these problems, DC-AC hybrid rapid heating method is proposed to preheat LiBs at high SOC operated from low temperatures. In the proposed method, a fractional order circuit model is adopted to derive a total impedance of a LiB which is used to calculate the optimal excitation parameters of a DC-AC preheating at different conditions. Experimental results demonstrate that the proposed strategy can preheat a LiB from −20 °C to 10.02 °C within 443s and a series-connected LiB pack from −19.26 °C to 10.97 °C within 395s at an average heat generation rate of 4.07 °C/min and 4.6 °C/min, respectively. No appreciable capacity fade for the LiB is observed after the proposed method is used to preheat LiBs after 210 cycles.