According to incomplete statistics from relevant institutions, as of September this year, more than 26 expansion projects related to the production of energy storage batteries and power batteries have been announced, with a total investment of over 290 billion yuan and a total production capacity of 820GWh.

The process and product goals pursued by energy storage cells and power cells are different - power batteries pursue high energy density and do not require high life expectancy; while energy storage batteries pursue long life and high consistency, while high power requirements are not high. There are certain differences between the two, and less and less can be shared on the production line. In the planning of many leading lithium battery companies, setting up production lines for energy storage batteries has been put on the agenda. So what are the differences between energy storage batteries and power batteries?

Different applicable scenarios

Real-world applications have different requirements on the performance and service life of the two

Lithium-ion batteries can be divided into consumer, power and energy storage batteries according to the application field. At present, power batteries and energy storage batteries are the areas with the greatest development potential for lithium batteries in the future. Batteries used for electric vehicles and batteries used for energy storage devices are essentially energy storage batteries.

There is no difference in technical principles between energy storage batteries and power batteries, but due to different application scenarios, practical applications have different requirements for their performance and service life.

Power and energy storage battery system products can be divided into cells, modules and battery packs according to different product forms. Cells are the core basic building blocks of power battery products. A certain number of cells can be formed into modules and further assembled into battery packs. The final form of application in new energy vehicles is battery packs.

System structure and cost structure of energy storage battery and power battery

The complete electrochemical energy storage system is mainly composed of battery pack, battery management system (BMS), energy management system (EMS), energy storage converter (PCS) and other electrical equipment.

The battery pack is the most important part of the energy storage system; the battery management system is mainly responsible for the monitoring, evaluation, protection and balance of the battery; the energy management system is responsible for data acquisition, network monitoring and energy scheduling; the energy storage converter can control the storage battery. It can perform the conversion of AC and DC during the charging and discharging process of the battery pack.

In the cost structure of the energy storage system, the battery is the most important part of the energy storage system, accounting for 60% of the cost; by the energy storage inverter, accounting for 20%, and the EMS (energy management system) cost accounting for 10%, The cost of BMS (battery management system) accounts for 5%, and the others are 5%.

Power battery PACK refers to the battery pack of new energy vehicles, which provides energy for the operation of the whole vehicle. Vehicle power battery PACK basically consists of the following five systems: battery module, battery management system, thermal management system, electrical system and structural system.

The cost of the power battery system consists of comprehensive costs such as cells, structural parts, BMS, boxes, accessories, and manufacturing costs. The battery cell accounts for about 80% of the cost, and the cost of the pack (including structural parts, BMS, box, accessories, manufacturing costs, etc.) accounts for about 20% of the cost of the entire battery pack.

Difference between energy storage battery and power battery BMS

In the battery pack, BMS (Battery Management System) is the core, which determines whether the various components and functions of the battery pack can be coordinated, and is directly related to whether the battery pack can provide power output for electric vehicles safely and reliably. Of course, the connection process, space design, structural strength, system interface, etc. of the structural parts also have an important impact on the performance of the battery pack.

The energy storage battery management system is similar to the power battery management system, but the power battery system is on a high-speed electric vehicle, and has higher requirements for the battery's power response speed and power characteristics, SOC estimation accuracy, and the number of state parameter calculations. The relevant adjustment functions also need to be implemented through the BMS.

The cycle life of energy storage batteries and power batteries is very different

Depends on material, compaction density, etc.

There is a big difference in the cycle life requirements of power batteries and energy storage batteries. Taking an electric vehicle as an example, the theoretical life of a ternary lithium iron phosphate battery pack is 1200 times. According to the frequency of use, it is fully charged and discharged once every three days and 120 times a year. The calendar life of the ternary lithium battery reaches ten years.

The energy storage battery is charged and discharged more frequently. Under the premise of the same 10-year calendar life, there is a higher requirement for the cycle life. If the energy storage power station and household energy storage are charged and discharged at a frequency of once a day, the energy storage lithium battery The cycle life is generally required to be greater than 3500 times. If the charge and discharge frequency is increased, the cycle life requirement is usually required to reach more than 5000 times.

From the perspective of battery structure, factors such as material type, positive and negative electrode compaction density, moisture, coating film density and other factors will affect the battery cycle performance.