Writer： admin Time：2025-12-06 14:30:59 Browse：6℃
In the power generation-side energy storage scenario, the safety issues of energy storage batteries are amplified due to four core characteristics: "large-scale grouping, long-term grid connection, complex operating conditions, and exposure to extreme environments." The risks are not limited to individual cell failures, but may trigger "chain reactions" that threaten the safety of the entire energy storage station, surrounding environment, and the power grid.
In the power generation-side energy storage scenario, the safety issues of energy storage batteries are amplified due to four core characteristics: "large-scale grouping, long-term grid connection, complex operating conditions, and exposure to extreme environments." The risks are not limited to individual cell failures, but may trigger "chain reactions" that threaten the safety of the entire energy storage station, surrounding environment, and the power grid. Specific safety issues can be expanded into five dimensions: risks from the cells themselves, system grouping risks, operating condition adaptation risks, environmental adaptation risks, and operational and maintenance risks. Each type of risk corresponds to the unique characteristics of the power generation-side scenario:
The cell is the smallest unit of an energy storage battery, and its material characteristics or manufacturing defects may gradually be exposed during long-term operation in the power generation scenario, becoming the "trigger" for safety accidents. Compared to power batteries, the power generation side requires higher "long-term stability" for cells, so the following risks are more pronounced:
The commonly used lithium iron phosphate (LiFePO4) batteries in power generation, while safer than nickel-cobalt-manganese (NCM) batteries, may still trigger thermal runaway under the following conditions during long-term operation at "high state of charge (SOC, e.g., over 90%)" or "full power charge/discharge":
The structure of the positive material (such as LiFePO4) collapses under long-term high voltage, releasing oxygen;
The electrolyte decomposes at high temperatures (e.g., above 60°C) or high voltage, producing flammable gases such as CO and HF;
Lithium dendrites form on the negative electrode (especially during low-temperature charging or deep discharge at low SOC), piercing the separator and causing internal short-circuiting.
Energy storage cells need to operate for more than 20 years on the power generation side, and material aging accelerates, increasing the likelihood of thermal runaway over time.
Small manufacturing defects (such as burrs on the current collector, wrinkles in the separator, or moisture retention) in the cells may not manifest in 5-8 years of use in power batteries but will be amplified during 20 years of long-term cycling on the power generation side:
Burrs on the current collector gradually wear down the separator, ultimately causing an internal short circuit;
Moisture retention reacts with the electrolyte, generating gases that cause the cell to swell, thereby exerting pressure on adjacent cells and causing system-wide failures.
Power generation-side energy storage systems are often large-scale, GWh-level plants, requiring thousands to tens of thousands of cells to be connected in series/parallel into a "module - battery cluster - battery room" three-tier structure. This "large-scale grouping" feature makes it easy for the failure of a single cell to spread through "heat, electricity, and fire" in three pathways, creating systemic risks. This is the core pain point in power generation-side safety:
In large-scale energy storage stations, cells are densely arranged (e.g., a single battery room may house hundreds of modules) with typically only 10-20 cm spacing. To maximize energy density, cooling space is limited. If a single cell undergoes thermal runaway (with temperatures reaching over 800°C), it can spread through three main pathways:
Heat conduction: High temperatures are transferred to adjacent cells via metal brackets and cables, triggering their thermal runaway;
Heat radiation: Flames directly radiate to surrounding modules, igniting flammable materials like electrolytes;
Gas explosion: Flammable gases (such as CO, CH4) released from thermal runaway accumulate in the enclosed battery room. Once they reach the explosive limit (e.g., CO volume fraction of 12.5%-74%), a spark can trigger an explosion, spreading throughout the station.
For example, in 2021, a fire at an energy storage station in California occurred when thermal runaway in a single cell spread throughout the battery cluster in just 10 minutes, ultimately destroying the entire station.
The voltage and current in a grouped energy storage system are extremely high (e.g., a battery cluster may have voltages exceeding 1500V, and charge/discharge currents can reach thousands of amperes), meaning electrical safety risks are far higher than in small-scale energy storage:
Overcharging/Overdischarging causing cell damage: If the consistency of cells in a group is poor (e.g., significant capacity or internal resistance deviation), certain cells may overcharge (voltage exceeding 3.65V) during charging, leading to electrolyte decomposition. Similarly, during discharge, cells with lower capacity may discharge too quickly, and excessive voltage drop (below 2.0V) leads to lithium dendrite growth, which can trigger safety accidents.
Faults in connections and cables: Long-term operation at high currents can cause contact resistance to increase at cell terminals, module connectors, or cable joints (due to oxidation or loosening). This can lead to localized overheating (temperatures may exceed 150°C), igniting surrounding insulating materials and triggering fires.
The core task of power generation-side energy storage is to "smooth out fluctuations in renewable energy" and "respond to grid frequency regulation." This requires frequent switching between complex operating conditions such as "high-rate charge/discharge," "wide SOC range," and "current fluctuations." These conditions intensify "stress damage" to batteries, indirectly leading to safety problems:
Under grid frequency regulation, energy storage batteries may need to charge or discharge at a high rate (e.g., 2C-5C within 10-30 seconds). For a 100MWh system, this means outputting 200-500MW power. At this time, polarization effects are significant, generating a large amount of joule heat:
If the cooling system cannot dissipate the heat in time, the internal temperature of the cell may rise above 60°C within 1 minute, exceeding the electrolyte decomposition threshold (usually 65°C), triggering thermal runaway;
High rates also accelerate lithium dendrite growth on the negative electrode, making it 3-5 times more likely to pierce the separator compared to standard 1C rates.
During extreme fluctuations in renewable energy output (e.g., sudden drops in solar power output on cloudy days or wind power surges during storms), energy storage batteries may need to frequently charge/discharge within a wide SOC range (e.g., 10%-90%, or even 5%-95%):
Low SOC (≤10%) risks: Insufficient lithium content on the negative electrode leads to collapse of the carbon structure, and lithium dendrites are more likely to form, increasing short-circuit risks;
High SOC (≥90%) risks: Excessive de-lithiation of the positive material (such as LiFePO4) leads to reduced structural stability and increased oxygen release; at the same time, electrolyte reactions at the positive electrode interface intensify, leading to the breakdown of the solid electrolyte interface (SEI) film and triggering exothermic side reactions.
This wide range operation accelerates battery degradation (2-3 times faster than the conventional 20%-80% SOC range), and material damage accumulates, gradually reducing the thermal runaway triggering threshold.
Power generation-side energy storage stations are often located outdoors (e.g., near photovoltaic bases or wind farms), requiring them to withstand extreme conditions such as high temperatures, low temperatures, high altitudes, humidity, and dust. These environmental factors directly compromise battery safety performance:
High-temperature environment (e.g., 40-50°C in summer in southern regions): Battery room temperatures may exceed 55°C, exceeding the battery’s normal operating temperature limit (usually 45°C), leading to:
Reduced electrolyte viscosity, lowered ion conductivity, and increased polarization heat;
Reduced thermal stability of the positive material, reducing the thermal runaway threshold from over 200°C to below 150°C.
Low-temperature environment (e.g., -20 to -30°C in northern winters): Battery internal resistance increases significantly (2-3 times higher than at room temperature). Charging at low temperatures leads to faster lithium dendrite formation on the negative electrode surface, and battery charging/discharging efficiency drops. If large current charging is forced, localized overheating may occur, triggering safety incidents.
High altitude (e.g., Qinghai, Tibet photovoltaic stations at altitudes over 3000m): Air is thinner, and heat dissipation efficiency is lower (30% lower than on plains). The battery room temperature rises, and low air pressure reduces the sealing performance of the battery room, allowing
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