The energy storage industry is developing rapidly, and the demand for energy storage batteries is increasing. Enterprises are adopting technological innovations and continuously improving battery capacity. From 280Ah to 300Ah, and then to 580Ah, the battery capacity continues to expand, showing an obvious trend towards large-scale. This trend has had a positive impact on the energy storage industry, but it also brings a series of challenges and safety hazards.
Profit and Challenges of Large-capacity Energy Storage Batteries
Industry experts have conducted a profit model analysis of energy storage projects, and the results show that the emergence of large batteries reduces the overall system cost and improves the economic return of projects. Therefore, the design of large battery cells has become the main development direction of future energy storage batteries. The design of high-capacity batteries not only reduces the cost of battery housing and cover plate, but also improves the material utilization rate, thereby enhancing the price competitiveness of the battery.
However, large-capacity batteries also come with a series of challenges. When the battery capacity reaches 320Ah, the internal temperature of the battery may exceed 800℃, which is higher than the decomposition temperature of lithium iron phosphate. This poses great challenges to the safety, energy design, and production processes of the battery.
Balance between Safety and Energy Density of Energy Storage Batteries
The research and development of energy storage batteries often face the “impossible triangle” problem, that is, it is impossible to achieve high energy density, high cycle times, and high safety simultaneously. Among them, energy density is the primary issue that cannot be ignored in battery design. Improving energy density means that the battery must choose thinner separators and use materials under extreme pressure compaction and areal density. This extreme design makes it more difficult for the battery to absorb liquid, which affects cycle performance and also results in thinner separators and reduced safety performance of the materials.
Therefore, battery manufacturers need to find a balance between energy density and safety. High energy density may bring certain safety risks, while excessive emphasis on safety may reduce product competitiveness.
System-level Safety of Large-capacity Energy Storage Batteries
The application of large-capacity batteries is a double-edged sword. Although they reduce costs and accelerate market development, they also bring a series of technical issues and safety hazards. The system-level safety of large energy storage batteries covers multiple aspects, including cell safety design, thermal propagation isolation design, system warning mechanism design, and fire-fighting system design.
From the perspective of cell components, with the improvement of automated equipment, the production control capability of cell manufacturers has continuously improved. At the same time, the improvement of automated detection equipment and methods provides better means for safety screening before the cells are shipped. In the field of materials, the application of membrane systems with better heat resistance and stability, as well as auxiliary additives, is expected to enhance the safety and stability of the battery.
However, from an electrochemical perspective, lithium-ion batteries still cannot guarantee absolute safety. Therefore, future safety design must adopt systematic solutions, including system design, safety warnings, and firefighting measures.
Since it is unlikely for lithium-ion energy storage batteries to self-ignite after losing control, the ability of integrators to control open flames is critical. The initial loss of control will produce hydrogen and carbon monoxide, both of which are flammable, so energy storage integrators need to take measures to ensure that fires can be quickly controlled in case of failure.
In conclusion, the development of large battery cells in energy storage batteries brings huge opportunities, but also challenges and safety hazards. By considering energy density, safety, and system-level safety comprehensively, the energy storage industry can find a balance between large and safe battery cells and promote further development of energy storage technology.