Critical performance indicators of battery performance

The core technical indicators of power lithium-ion batteries include energy, energy density, charge-discharge rate, cycle life, safety, consistency, reliability and many other indicators. Among them, in the case of a given vehicle weight and normal operating conditions, the battery energy determines the cruising range of the new energy vehicle. Battery energy (Wh) is equal to energy density (Wh/L) multiplied by battery volume (L), or specific energy (Wh/kg) multiplied by battery mass (kg). Since new energy vehicle manufacturers must strictly control the space occupied by the battery in the body of a specific model, under the condition of a certain volume of power lithium-ion battery, the higher the energy density of the battery cell, the greater the battery energy and the cruising range The longer it is. Therefore, since 2017, the country began to refer to the energy density of power lithium-ion batteries [the energy density of the battery cell is called the single energy density. After the battery PACK is grouped, the overall energy density will drop significantly. This energy density is called the system Energy density, the national policy assessment is the system energy density] indicator is included in the scope of subsidy assessment to promote the technological development of power new energy vehicles and battery industries. In summary, energy density is the most important indicator considered in the design of power lithium-ion batteries. The consistency of power lithium-ion batteries is another important indicator. The performance indicators of a single battery include energy, internal resistance, open circuit voltage and so on. There are many single cells in series and parallel in the battery system (a Tesla uses as many as 5000 to 7000 cylindrical 18650 cells). If the internal resistance of many single cells cannot be kept highly consistent, when the same current flows, the cells with large internal resistance will heat up, and safety accidents such as explosions will occur. On the other hand, there is a short board effect due to the energy and life of the battery system (determined by the battery with the smallest energy and the shortest life in the system). Therefore, for power lithium-ion battery processing companies, it is necessary not only to process high-energy-density batteries in the laboratory, but also to ensure that the consistency of the processed batteries is strong, in order to meet the requirements of car companies for batteries. To ensure the consistency of the battery, more advanced battery processing equipment, strict process control and related supporting technologies are required. There are often contradictions in the pursuit of various performance indicators of power lithium-ion batteries. For example, increasing battery energy density often reduces battery consistency, improving fast charging performance often reduces battery life, and increasing power often sacrifices battery energy density. To improve performance indicators in multiple aspects at the same time, the company needs to improve its own equipment, technology, and management level, and at the same time choose multiple goals when designing products. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Can lead-acid batteries and lithium batteries be charged together?