The development of high-capacity energy storage power stations has brought economic benefits, but it has also brought more serious security challenges. As capacity increases, resulting in increased battery energy release and safety risks.
In recent years, the frequency of fire and explosion accidents in energy storage power stations has increased, which has attracted widespread attention. The energy storage industry attaches importance to battery safety and is committed to improving the safety performance of energy storage power stations.
1. Market for high-capacity cells
In recent years, China's energy storage industry has experienced explosive growth. In order to better seize the market and seek higher economic benefits, the top 10 energy storage battery cell companies continue to optimize the structure and design of energy storage batteries to achieve greater energy density and longer service life. Sort out some of the leading energy storage manufacturing companies, and large capacity development has also become an important trend at present.
- SVLOT produces special cells for storage of 325Ah laminated short knife L500. The thickness is only 21MM, which is 2/3 thinner than the 280Ah energy storage cells.
- Envision AESC's 315Ah energy storage cell products increase energy density by 11% while maintaining the same size.
- The 320Ah large-scale energy storage batteries produced by Great Power has increased the monomer's capacity by 14%.
- EVE introduced a 560Ah ultra-high-capacity energy storage cell that can store 1.792kWh of energy in a single battery.
However, large capacity has also brought new challenges to the development of energy storage batteries. As capacity increases, so does the energy density inside the batteries, leading to higher energy release and more serious safety risks. In recent years, fires and explosions have occurred in energy storage power stations, and even serious employee casualties have occurred.
The safety of energy storage systems has always been a concern for everyone. It is generally believed that lifepo4 battery is relatively safe, and this is true for small lithium iron phosphate batteries. But for large-capacity batteries, the internal temperature can exceed 800 degrees, which exceeds the temperature at which the lithium iron phosphate cathode decomposes.
For small batteries, because there is a chain reaction in the middle, there is a partition, and the cathode material basically does not decompose until more than 500 degrees, so small batteries are not in this range. However, the capacitive battery can reach 700-900 degrees, and it can break through, crossing this separator and causing the cathode material to decompose.
Today's energy storage batteries are basically more than 300 Ah hours, which is still very dangerous. On the one hand, we must expand capacity and reduce costs, and on the other hand, we must maintain the bottom line of security risks. How to balance both?
2. The industry takes battery safety seriously
While energy storage power stations are developing in the direction of large capacity, energy storage safety and fire protection will also face more severe tests, and safety is the bottom line of the development of the energy storage industry. Since 2011, there have been more than 70 security incidents worldwide.
In 2022, there were also 17 accidents worldwide, excluding home energy storage. Two major causes of explosions in power stations: On the one hand, the root cause of the combustion explosion of lithium-ion batteries is the thermal runaway of the batteries. If the safety and quality of energy storage batteries cannot be guaranteed, it is easy to escape heat under general conditions of abuse.
On the other hand, the battery energy storage system contains BMS, PCS, transformers and related relay protection equipment and communication equipment. There may be quality defects, irregular installation and commissioning processes, unreasonable settings, inadequate insulation and other factors, which directly or indirectly cause safety problems in the energy storage system.
In the event of an accident, in addition to the hazards caused by the fire and explosion itself, toxic chemicals may also be released to create chemical hazards. Even when relevant personnel repair or rescue energy storage systems, electrical or physical hazards may occur. Increased demand for energy storage temperature control and fire protection.
Due to the frequent accidents of energy storage power stations, China's energy storage safety standards are closer to global standards. With continuous improvement and tightening, the importance of energy storage fire protection and temperature control systems is expected to be significantly enhanced, and it is expected to usher in further development.
3. The current state of battery technology
At present, high-energy batteries such as high-nickel ternary should not be the focus of development, and there is uncertainty about whether all-solid-state batteries can succeed. At present, it seems that lithium iron phosphate batteries have high safety, long life, neither nickel nor cobalt and other metals, can become the main force, but to continuously improve cost performance.
Theoretically, lithium iron phosphate is not absolutely safe, but relatively safe. Safety accidents currently seen in energy storage power stations often occur in the absence or delay of early warning. In addition, existing fire protection measures are not configured for fire, which ultimately leads to serious accidents.
Of course, with the key position of energy storage in the "dual carbon" goal and the increase of operational projects, energy storage safety supervision and related research have also been paid attention to. The explosion index of lithium iron phosphate in high-capacity batteries is twice that of ternary batteries. Faced with a variety of energy storage technology routes, many experts said.
Although there are many battery technology routes at present, these existing technologies will not be the mainstream route in the future, and disruptive technologies will certainly appear in the future. In the future, the goal of electrochemical energy storage technology is "low cost, long life, high safety, and easy recycling", which needs to be disruptive innovation and breakthrough in technology.
4. Improve the safety of energy storage power stations
In order to improve the safety of energy storage power stations, a series of measures need to be taken:
First of all, the construction of an early warning system should be strengthened, including real-time monitoring of temperature, voltage, current, pressure and other parameters of energy storage power stations to ensure that potential safety risks can be detected and responded to in a timely manner.
Secondly, in view of the special nature of energy storage power stations, special fire protection measures and emergency plans are established to deal with emergencies such as fires.
In addition, it pays attention to the design and process of the battery system, and adopts advanced thermal insulation materials and heat dissipation technology. Effectively control battery temperature and energy release to reduce safety hazards. At the same time, strengthen personnel training and management to ensure that operators have the necessary safety knowledge and skills to respond appropriately to various emergencies.