Preparation method of low-temperature and high-energy-density lithium ion battery

The invention discloses a preparation method of a low-temperature energy type lithium ion power battery. The preparation method of the low-temperature rechargeable lithium ion power battery cell comprises the steps of pole piece manufacturing, secondary rolling, liquid injection, standing, secondary liquid injection, formation, standing and capacity grading. According to the invention, the processis simple to operate, materials with excellent low-temperature dynamics are selected, the process of secondary rolling and secondary liquid injection is adopted, the sufficient wettability of an electrolyte and positive and negative electrode active materials is improved while the high energy density is ensured, and the electrochemical reaction is facilitated. The electrolyte with a proper low-temperature additive is selected, so that the uniformity, compactness and stability of the generated SEI film are ensured, and the charging and discharging of the battery cell are prevented from being influenced by overlarge im