Sandwich self-heating structure-based lithium-ion battery system and its application in the fuel cell bus for Beijing Winter Olympic Games

Hydrogen fuel cell vehicles (HFCVs), consisting of dual energy sources of fuel cell system (FCS) and lithium-ion battery system (LIBS), have become the technological frontier of electric vehicles due to the advantages of no mileage anxiety, fast hydrogen refueling, and zero emissions. However, the deterioration of battery performance at low temperatures makes it difficult to start the FCS and seriously hinders the application range of HFCVs. Herein, a sandwich self-heating structure-based LIBS is proposed to realize rapid self-heating and performance recovery of the LIBS without relying on external energy and achieve a fast cold start of the HFCV at extremely low temperatures. Furthermore, the proposed LIBS were successfully applied to all fuel cell buses in the core area of the 2022 Beijing Winter Olympic Games in batches. Firstly, compared with the mainstream heating methods, this sandwich self-heating structure has the advantages of fast heating speed (5.9 degrees C/min), high heating effi-ciency (78.75 %), and good temperature uniformity. More importantly, this structure has a small impact on the life and energy density of the LIBS. Secondly, in response to the severe road conditions in the Winter Olympic Games area, we matched the FCS and sandwich self-heating LIBS parameters based on multi-objective optimi-zation and realized fast cold start and rapid performance improvement of fuel cell buses. Thirdly, the sandwich self-heating structure can realize the cold start of FCS with a smaller LIBS, which provides a new possibility to reduce the cost and light weight of HFCVs. Finally, the configuration is also applicable to pure electric vehicles, showing great application potential.