What is the difference between energy storage batteries and power batteries? Some people vividly compare it to "converters" and "generators". According to different application scenarios, the former is mostly used in power systems and requires low cost and long lifespan; The latter mainly provides power for vehicles and pursues high energy density.

 

Although the production lines of the two can be shared, with the rapid development of the energy storage industry, the scale of energy storage power stations can often reach the level of hundreds of megawatts or even gigawatts. Owners are calling for customized and specialized energy storage batteries. In the opinion of Liu Yong, Secretary General of the Energy Storage Application Branch of the China Chemical and Physical Power Industry Association, in the future, energy storage batteries must open up their own independent development track. This is not only a need for cost reduction and efficiency improvement, but also a requirement for safe development.

 

Large capacity is the trend

 

In an electrochemical energy storage system, the cost of batteries accounts for about 60%. In recent years, the scale of the energy storage industry has expanded rapidly, and with the pressure of cost reduction, there is an urgent demand for high economic efficiency of energy storage batteries in the industry.

In 2020, Ningde Times took the lead in launching a 280Ah battery cell with a long cycle life, gradually replacing the original 50Ah-100Ah battery cell and becoming the standard configuration for energy storage project bidding or product procurement. Mainstream battery manufacturers in the industry have followed suit and intensively launched 280Ah or even larger capacity battery cells.

In May this year, Chuneng New Energy released the "Chuneng No.1" product, with a cell capacity of 280Ah and a single cell cycle life of over 10000 times. In August, Xiamen Haichen Energy Storage released its first 300Ah electric energy storage dedicated battery and large cylindrical household energy storage dedicated battery. In October, Yiwei Energy Storage released a new generation of energy storage battery LF560K, further increasing the battery cell capacity to 560Ah. Battery manufacturers are accelerating their competition on the high capacity battery cell circuit.

There are already large customer orders and the market response is very enthusiastic. Delivery will be scheduled for the first quarter of next year. According to Zhang Wancai, the energy storage product manager of Haichen, the development of energy storage dedicated batteries towards larger capacity is one of the technological iteration trends. Large capacity batteries reduce the cost of energy storage systems by diluting the cost of battery structural components, reducing the number of system components in groups, simplifying production line processes, reducing the number of equipment, and reducing labor input.

Regarding this, Liu Yong agrees that the development path of energy storage batteries is to reduce costs and increase efficiency through technological innovation and upgrading. Small capacity batteries are used, with a large number of parallel connections and a larger system installation area. However, using large capacity battery cells can effectively reduce the number of prefabricated cabins, and the cost of electricity consumption can also be reduced to a certain extent, significantly improving the overall investment income of users.

Yuan Dingding, Chief Technical Officer of Yiwei Lithium Iron Lithium Battery, presented a set of data: compared to the previous LF280K energy storage dedicated battery, using LF560K battery can reduce the number of battery cells by 50%, reduce the number of battery pack components by 47%, and improve production efficiency by 30%.

 

Safety is a prerequisite

 

Industry insiders believe that energy storage batteries are entering a period of technological transformation, with high voltage and liquid cooling systems being highly sought after in the market, in addition to large capacity.

At present, more and more domestic manufacturers are starting to produce and develop dedicated energy storage battery production lines, including Sunshine Terrace New Energy, Yiwei Lithium Energy, Penghui Energy, Haichen Energy Storage, Ruipu Lanjun, Chuneng New Energy, and Yuanyuan Power. Battery companies have all released dedicated energy storage batteries to seize the development opportunity.

It is worth noting that the research and development of energy storage batteries must be based on safety, and battery capacity is not blindly pursued. Too large increases safety risks. Increasing capacity can lead to poor heat dissipation performance of the battery itself. At the same time, expanding the battery may cause cell bulging, which can lead to overcharging and thermal runaway, making it difficult to cope. Therefore, it is necessary to balance the thermal management of the battery, "Liu Yong said.

"Safety is the bottom line of the development of the energy storage industry." Industry insiders stressed to reporters that the energy storage industry is still in its early stage of development, and the technical standards and acceptance standards are not perfect enough, so customers are difficult to identify various energy storage and their products. In this situation, some enterprises that do not have the strength blindly embark on large-scale projects, increasing security risks. Large capacity is not infinite amplification, it is necessary to achieve a balance of large capacity, high safety, and long cycle life

Zhang Wancai also stated that battery energy storage is not a source of energy, but rather a transit station with capacity limitations.

So, which scenarios are suitable for small batteries and which scenarios require large batteries? The battery capacity is closely related to the installed capacity and application scenarios of energy storage systems/power stations. For example, large storage systems are usually more suitable for matching large capacity battery cells, which can significantly improve the energy density of energy storage systems. This is a development trend in the large storage market, and small capacity batteries are sufficient for household energy storage.

 

Manufacturing capacity still needs to be strengthened

 

This year, the demand for energy storage market is exceptionally strong, and the supply of 280Ah batteries is facing a tense situation. For manufacturers, whether it is building a dedicated energy storage battery production line or upgrading and transforming the existing power battery production line, it requires a certain expansion period.

It is understood that there are two main processes for the production of energy storage batteries: lamination and winding. The winding process has a high degree of automation and production efficiency. However, the consistency of 280Ah battery cells produced by winding has far higher manufacturing process requirements than 50Ah to 100Ah battery cells.

Large capacity batteries pose great challenges to design and manufacturing capabilities, "Liu Yong explained. Small cells generally use winding technology with high production efficiency, while large cells need to upgrade production lines to meet the required technical parameters. How to ensure the safety, efficiency, and stability of electrochemical material injection during the production process is also crucial, which are currently urgent challenges for energy storage batteries to overcome.

The production efficiency of large cells is lower than that of small cells, which is a physical law. "Zhang Wancai further pointed out that large capacity batteries have put forward new requirements for production equipment. Taking the existing 280Ah intelligent production line of Haichen Energy Storage as an example, the R&D and manufacturing teams have carried out corresponding design and development on all assembly and testing stage process equipment, and have done a lot of work. In the future, creating faster production lines with higher production capacity still requires continuous technical breakthroughs from practitioners.

In addition, the energy storage market has not yet reached the stage of large-scale development. In the first half of this year, the scale of newly planned and under construction new energy storage projects is close to 130 gigawatts per hour, and the actual operating volume is less than 1.5 gigawatts per hour. The energy storage business model is not yet mature, and coupled with the impact of rising prices of upstream raw materials, battery companies are also cautious in expanding production.