“High & Large energy storage” has gradually become a new trend in the development of the lithium battery energy storage industry.
A new trend
“High” refers to the high-voltage level and large-capacity battery cells of the energy storage system, “Large” refers to the current popular large-capacity lithium battery cells in the ESS industry, which can greatly increase the energy density of the energy storage system and is one of the important trends in system development choices.
At present, ” High & Large cells ” mainly refers to the 280Ah large battery cells, which seems to be becoming a “new hot” in the large-scale energy storage market.
Era of 280ah cells
The era of 280Ah large cells for energy storage batteries has been opened !
Recently, some lithium battery manufacturers have expanded the production of 280Ah batteries, some have deployed 5 lithium battery manufacturing production lines, built a new generation of energy storage lithium battery production bases, and expanded the production of 280Ah and other power storage application battery products.
In addition, energy storage products in the marine market have also been applied to 280Ah series cells and various battery packs, which shows that large-capacity cells have gradually become a new trend.
There are currently more than 10 cell companies in China manufacturing 280Ah battery products, most of which are 280Ah lithium iron phosphate battery products.
Larger capacity cell
Whether it is a cylindrical lithium battery or a square lithium battery, it is gradually developing towards a larger capacity of a single cell.
Cylindrical lithium batteries have been continuously developed from 18650 to 21700, 4680 and other large cylinders, and square lithium batteries have changed from VDA size cells, to MEB platform cells, and then to the current stage of blade batteries.
The direction of technological evolution is mainly to continuously improve the capacity of single lithium battery cells. The gradual upgrading of the single cell capacity of the prismatic cell from the traditional 50/100Ah to 280Ah also conforms to the above evolution trend.
CATL’s 280ah batteries
Looking back at the history of 280Ah batteries, in 2020, CATL launched its 271Ah & 280Ah batteries with long cycle life, and completed UL 9540A testing and mass production. Based on this long-life battery technology, CATL launched an outdoor liquid-cooled electric cabinet in 2020.
This product uses a 280Ah lithium iron phosphate battery with a discharge rate of 1C and a cycle life of 10,000 times. However, CATL never imagined that it would open the era of energy storage 280Ah batteries.
280Ah large batteries is in rapidly increasing: in January 2022, China HN issued a tender announcement for the procurement and leasing of energy storage batteries, requiring that the cell capacity should not be less than 280Ah, Solar company also purchases 150/280/300Ah lithium battery cells for photovoltaic energy storage systems.
This shows that large-capacity cells have become the “standard” for of high-profile and large-scale energy storage market orders in the energy storage lithium battery cells development.
Core standards of BESS ?
Can 280Ah cells become one of the core standards of battery ESS? What is the optimal solution for the battery cell capacity of the energy storage system?
There is still some controversy in the industry, because it is different from China, the ternary cells of Samsung SDI and LG Chem in foreign countries do not exceed 120Ah, especially Tesla has brought the advantages of small lithium battery cells to the extreme.
The 280Ah battery is derived from the power battery. However, the difference between the sector of energy storage batteries and the sector of power batteries is somewhat large, so whether 280Ah batteries can become the mainstream standard of energy storage batteries remains to be verified.
Enterprises that choose 210Ah large-capacity energy storage cells believe that “cells should not only pursue large capacity, but should consider safety and long cycle life.
They choose 210Ah energy storage cells mainly based on investment cost considerations, the use of large-capacity cells should also consider the high security requirements of the power grid for the energy storage system.
Disadvantages
Generally speaking, the energy density of large-capacity cells is higher, the heat dissipation is relatively more difficult, and the consistency control of the energy storage system is more difficult, which is a disadvantage.
The disadvantage of small-capacity cells is that when multiple series and parallel connections are required in the system integration process, it is impossible for BMS and EMS to collect operating data for each node.
If data collection is performed for each cell, then the cell management technology is more complex and the integration cost is high.
Due to the limitations of BMS, the energy storage cell should be larger, but it is not the larger the better. Because the larger the battery cell, the larger the energy, and once there is a risk, the rate and total amount of energy released are greater.
So you can’t blindly pursue the capacity. The general principle should be to combine the elements of high safety and long cycle life.
At present, the 280Ah capacity is generally recognized as a unified specification in the short term. With the iteration of technology, cell capacity may continue to increase, but size and capacity will gradually form a fixed standard.
From the perspective of energy storage system integrators, the battery cell specifications in the market will gradually be required to be unified.
Advantages & technical challenges
280Ah battery has obvious advantages, but there are still certain technical challenges
At present, 280Ah large-capacity batteries are gradually recognized by the large-scale energy storage market. This trend is still obvious, including four advantages:
- Reduce the number of parallel connections;
- Can support larger hour-service energy storage systems;
- Easy & better BMS management;
- Cost advantage for mass application
Compared with batteries with a capacity of 50-100Ah, the advantages of large cells of 280Ah and above are mainly concentrated in:
- The use of pack components is reduced, which has a natural cost advantage; the volumetric energy density is higher;
- The large-capacity cells improve the safety of the BMS;
- The use of large-capacity cells enables the integration of the assembly process on the energy storage system to be more simplified, which can greatly save the cost of land infrastructure and containers.
Based on the above advantages, 280Ah cells are accelerating the replacement of traditional 50Ah and 100Ah battery cells in wind-solar power generation, power grids, shared energy storage and some large-scale mobile ESS applications that pursue low cost, large capacity and safety.
In terms of production process, 280Ah large cells mainly have two processes: lamination and winding. Among them, the advantages of winding are high degree of automation, high production efficiency, and the production line efficiency can reach 9-11PPM.
R & D, production challenges
However, the 280Ah battery produced by the winding process has poor consistency, and there are problems such as C angle when the mechanical stress of the battery increases and the thickness increases.
Due to the larger contact surface of the electrode sheet, there are no problems such as mechanical stress and C angle, and the produced large cell products have better consistency and longer cycle life.
The shortcomings of the lamination process mainly include the removal of electrode burrs and the low production efficiency. At the same time, the yield rate is not as good as that of the winding process.
In all, the large-scale single battery cells also bring certain challenges to product development and production.
- The first is the increase in the size and capacity of the battery, which leads to the deterioration of the heat dissipation performance of the battery itself.
- Second, the bulging problem of the battery is more obvious than that of the small-sized battery.
- Finally, the production efficiency of the 280Ah large battery is low, which is much lower than 50 and 100Ah square cells.
In this case, the large-scale development of 280Ah will inevitably require more cell design innovations, especially innovations in thermal balance and electrical balance design, and innovations in thermal management technology.
