With the rapid development of renewable energy, the energy storage cell industry has experienced significant growth, reaching an installed capacity of 21 GW by 2023. Currently, lithium iron phosphate (LFP), lithium nickel cobalt manganese oxide (NCM), and lead-acid batteries (LAB) dominate the market, accounting for 97% of energy storage cell shares. Secondary use lithium iron phosphate (SULFP) and secondary use lithium nickel cobalt manganese oxide (SUNCM) cells are emerging as promising alternatives, extending product lifespans and reducing the demand for new cells, thereby alleviating resource shortages in metals like lithium, nickel, and cobalt. However, energy storage cells are inherently energy-intensive products, accompanied by environmental pollution during production, use, and recycling processes. The promotion and development of these cells often lack sufficient consideration of environmental impacts, and differences in production, recycling methods, and performance during use lead to varied environmental effects, complicating the selection of eco-friendly options. Given that one of the development goals of energy storage cells is to reduce environmental pollution, clarifying the environmental impacts of different energy storage cells is crucial for the sustainable development of the industry.
Previous studies have employed life cycle assessment (LCA) methods to evaluate the environmental impacts of specific products, as LCA is an effective tool for assessing environmental effects from “cradle to grave.” In the energy storage cell field, some researchers have focused on comparing the environmental impacts of new lithium-based cells and LAB. For instance, one study found that new lithium-based cells performed better in most environmental indicators when used as backup power sources, while another study in the home energy storage sector indicated that LAB outperformed lithium-based cells in several impact categories. Additionally, comparisons among different types of lithium-based cells have shown that LFP cells generally have lower environmental impacts than NCM cells in home energy storage applications, though some studies report conflicting results, with LFP emissions slightly higher than NCM in certain scenarios. With the rise of secondary use cells, researchers have begun to assess their environmental impacts, with findings suggesting that secondary use lithium-based cells offer higher environmental benefits compared to LAB. However, existing studies lack comprehensive comparisons of multiple typical energy storage cells, often using varying functional units and system boundaries, making cross-comparisons difficult. Moreover, they do not fully account for the actual recycling rates in China’s energy storage cell industry. Therefore, this study selects lithium-based cells (LFP, NCM), secondary use lithium-based cells (SULFP, SUNCM), and LAB as research objects, establishes detailed life cycle inventories for five typical energy storage cells, and applies LCA methods based on China’s actual recycling situation. Using 1 kWh energy delivered as the functional unit, we comprehensively evaluate the average environmental impacts of these energy storage cells, identify hotspot life cycle stages, and explore the importance of allocation methods, cycle numbers, charge-discharge efficiency, and formal recycling rates. Finally, we assess the emission reduction potential of energy storage cells under future electricity structures to provide data support and decision-making references for the low-carbon development of the energy storage cell industry.
Materials and Methods
According to the ISO 14040 series standards, the LCA method consists of four steps: goal and scope definition, inventory analysis, impact assessment, and interpretation of results.
Goal and Scope Definition
The evaluation objectives include: (1) establishing full life cycle inventories for LFP, NCM, SULFP, SUNCM, and LAB, and comparing the average environmental impacts of five typical energy storage cells in China; (2) identifying the hotspot life cycle stages of energy storage cells; (3) assessing the importance of different recycling methods, battery cycle numbers, charge-discharge efficiency, and formal recycling rates; and (4) determining the emission reduction potential of energy storage cells under future electricity structures.
The evaluation scope covers the functional unit and system boundary. Previous studies often used 1 kWh battery capacity as the functional unit, but this does not account for battery cycle life, failing to reflect the functional performance of energy storage cells and potentially leading to inaccurate evaluation results. The core function of an energy storage cell is to serve as an energy delivery medium. Therefore, this study comprehensively considers battery capacity and cycle numbers, defining the functional unit as 1 kWh energy delivered over the battery pack’s life cycle. The system boundary encompasses the environmental impacts of the five energy storage cells from “cradle to grave,” including battery production, use, and recycling processes. Transportation and infrastructure differences between production facilities are not considered due to their significant variability.
The system boundaries for the five typical energy storage cells are illustrated in Figure 1. For new cells (LFP, NCM, LAB), the system boundary includes battery production, primary use, and battery recycling. For secondary use cells (SULFP, SUNCM), the boundary includes battery production, primary use, component recycling, battery repurposing, secondary use, and battery recycling. Inputs include energy and materials, while outputs include waste and emissions.
Inventory Analysis
The inventory analysis phase involves compiling data on inputs and outputs for each life cycle stage.
Battery Production Stage: The production stage for new cells includes raw material acquisition and battery assembly. Lithium-based battery packs primarily consist of cathode materials, anode materials, electrolyte, separator, casing, and battery management systems. For LFP cells, the cathode material is made from lithium iron phosphate, aluminum foil, binders, etc. For NCM cells, the cathode material comprises nickel-cobalt-manganese oxide compounds, aluminum foil, binders, etc. The anode material for lithium-based cells is mainly graphite and copper foil. In contrast, LAB has a simpler structure, composed of lead, lead alloys, sulfuric acid solution, and electrical control systems. For secondary use cells, cell production is not required; instead, retired power cells are disassembled, components are recycled, and new components are replaced. Thus, the repurposing stage for secondary use cells includes component manufacturing, battery assembly, and component recycling. Life cycle inventory data for the five energy storage cells and their material production processes are detailed in supporting files Tables 1-10.
Battery Use Stage: The use stage involves the application of cells in energy storage systems. Environmental impacts in this stage originate from electricity losses during charge-discharge cycles. Battery charge-discharge processes are influenced by various factors, including battery life and charge-discharge efficiency. Typically, battery life is closely related to cycle numbers, as increased cycles lead to reduced available capacity until the cell becomes unusable. Therefore, this study uses cycle numbers as a measure of battery life. To simplify calculations, formulas from previous research are adopted to estimate capacity loss for lithium-based cells, as shown in Equation (1).
$$ \xi = A \cdot e^{-\frac{E_a}{R \cdot T}} \cdot n^z $$
where ξ is the battery relative capacity loss (%), A is a constant, Ea is the activation energy (J·mol⁻¹), R is the gas constant (J·(mol·K)⁻¹), T is the temperature (K), n is the cycle number, and z is the power-law coefficient. For LFP cells, parameters from Han et al. are used: A, -Ea/R, T, and z values are 0.1825, 1324.65, 298.15, and 0.5878, respectively. For NCM cells, parameters from Li et al. are applied: A·e^(-Ea/(R·T)) and z values are 0.00362 and 0.588, respectively.
The formulas for electricity input, output, and loss during the use stage of lithium-based cells are given by Equations (2), (3), and (4).
$$ E_{\text{In}} = \sum_{i=1}^{n} (1 – \xi_i) \cdot E_I \cdot \text{DoD} \cdot \alpha^{-1} $$
$$ E_{\text{Out}} = \sum_{i=1}^{n} (1 – \xi_i) \cdot E_I \cdot \text{DoD} \cdot \alpha $$
$$ E_{\text{Loss}} = E_{\text{In}} – E_{\text{Out}} = \sum_{i=1}^{n} (1 – \xi_i) \cdot E_I \cdot \text{DoD} \cdot \frac{1 – \alpha^2}{\alpha} $$
where E_In is the total electricity input per unit product over the life cycle (kWh), E_Out is the total electricity output per unit product over the life cycle (kWh), E_Loss is the total electricity loss per unit product over the life cycle (kWh), E_I is the initial nominal capacity per unit energy storage cell (kWh), DoD is the depth of discharge, and α is the charge-discharge efficiency.
For LAB, the total electricity loss over the life cycle is calculated using Equation (5).
$$ E_{\text{Loss}} = \sum_{i=1}^{n} \omega_i \cdot E_I \cdot \text{DoD} \cdot \frac{1 – \alpha^2}{\alpha} $$
where ω_i is the percentage of remaining battery capacity at the start of each cycle. The degradation process of LAB is complex and nonlinear; for simplification, capacity is assumed to decrease linearly during the use stage. Currently, LAB cycle numbers typically range from 500 to 1200, with a value of 850 adopted in this study.
All energy storage cells are assumed to have a depth of discharge of 80%. The charge-discharge efficiency for lithium-based and secondary use lithium-based cells is set at 90% and 88%, respectively, while for LAB, it ranges from 75% to 80%, with a value of 77.5% used. Detailed parameters for the five energy storage cells are summarized in Table 1.
| Battery Parameter | Unit | LFP | NCM | SULFP | SUNCM | LAB |
|---|---|---|---|---|---|---|
| Initial Capacity | % | 100 | 100 | 80 | 80 | 100 |
| Retirement Capacity | % | 60 | 60 | 60 | 60 | 60 |
| Battery Capacity | kWh | 1 | 1 | 1 | 1 | 1 |
| Cell Energy Density | Wh·kg⁻¹ | 167.4 | 224.2 | 149.9 | 214.2 | — |
| Pack Energy Density | Wh·kg⁻¹ | 145.7 | 204.3 | 120.7 | 166.7 | 40 |
| Depth of Discharge | % | 80 | 80 | 80 | 80 | 80 |
| Charge-Discharge Efficiency | % | 90 | 90 | 88 | 88 | 77.5 |
Battery Recycling Stage: Based on the actual situation of battery recycling in China, LFP and NCM cells are primarily recycled using hydrometallurgical processes. The hydrometallurgical recycling process for LFP cells includes battery pretreatment (crushing and sorting), acid leaching, filtration, impurity removal, iron phosphate precipitation, powder distillation, lithium solution purification, and lithium precipitation. Recycled products include lithium carbonate, iron phosphate, non-ferrous metals, and plastics. For NCM cells, the hydrometallurgical process involves battery pretreatment, roasting and acid leaching, impurity removal, purification, leaching, and extraction. Recycled products include lithium carbonate, nickel sulfate, cobalt sulfate, manganese sulfate, non-ferrous metals, and plastics. LAB are recycled using pyrometallurgical processes, which include battery pretreatment, smelting of lead-containing materials, and acid gas recovery. Recycled products include lead, sulfuric acid, and plastics. The weight of cells before and after use is assumed to remain unchanged.
Life Cycle Impact Assessment
The levelized environmental impact of energy (LEIOE) is calculated by dividing the average environmental impact per unit product over its full life cycle by the total electricity output per unit product over its life cycle, as shown in Equations (6) and (7).
$$ \text{LEIOE} = \frac{\text{EI}_{\text{Unit}}}{E_{\text{Out}}} $$
$$ \text{EI}_{\text{Unit}} = \text{EI}_{\text{pro}} + \text{EI}_{\text{use}} + \left[ \rho \cdot \text{EI}_{\text{rec}} + (1 – \rho) \cdot \text{EI}_{\text{dis}} \right] $$
where EI_Unit is the average environmental impact per unit product (using 1 kWh nominal capacity cell as the unit product), EI_pro is the environmental impact of the production stage per unit product, EI_use is the environmental impact of the use stage per unit product, ρ is the formal recycling rate, EI_rec is the environmental impact of the recycling process per unit product, and EI_dis is the environmental impact of the disposal process per unit product (lithium-based cells are disposed of as general municipal solid waste, while LAB are treated as hazardous waste). The formal recycling rate for lithium-based cells is 20%, and for LAB, it is 90%.
Data sources include environmental impact assessment reports, open-source data from literature, and the Ecoinvent 3.8 database. The CML-IA baseline method is used to assess the life cycle environmental impacts of the five cells. Eight environmental impact categories are evaluated, as listed in Table 2.
| Environmental Impact Indicator | Abbreviation | Unit |
|---|---|---|
| Abiotic depletion potential | ADP | kg Sb eq |
| Abiotic depletion potential-fossil fuels | ADP-ff | MJ |
| Global warming potential (GWP100 a) | GWP | kg CO₂ eq |
| Human toxicity | HT | kg 1,4-DB eq |
| Acidification potential | AP | kg SO₂ eq |
| Eutrophication potential | EP | kg PO₄ eq |
| Ozone layer depletion | ODP | kg CFC-11 eq |
| Photochemical oxidation | PO | kg C₂H₄ eq |
Sensitivity Analysis of Influencing Factors
Environmental Impact Allocation Methods: Given the multifunctionality of battery life cycles, including primary and secondary use, economic allocation methods are used to distribute environmental impacts between primary and secondary products, compared with physical characteristics, 50/50, and cut-off allocation methods: (1) Economic allocation: Based on the economic value of primary and secondary products, the allocation coefficient is calculated by dividing the secondary product price by the primary product price. Currently, secondary cell prices are about 33% of new cells, yielding an allocation coefficient of 33%. (2) Physical characteristics allocation: Based on the service weight of products, the allocation coefficient is derived from the total energy delivered during secondary use divided by the sum of energy delivered during primary and secondary use. Using formulas from the battery use stage, the allocation coefficient is 59%. (3) 50/50 allocation: Assuming that when product secondary use is widespread, environmental impacts from production and recycling stages are evenly allocated to primary and secondary use stages, with a coefficient of 50%. (4) Cut-off allocation: No specific coefficient; the battery multi-life cycle system is divided at the repurposing stage. All environmental impacts from the production stage are attributed to the primary product (coefficient 0), while all impacts from the recycling stage are attributed to the secondary product (coefficient 1).
Other Influencing Factors: Additional factors include battery cycle numbers, charge-discharge efficiency, and formal recycling rate. Battery cycle numbers significantly affect electricity consumption during the use stage; charge-discharge efficiency influences electricity loss and output; and formal recycling rate affects the average environmental impact of the recycling stage. Sensitivity analysis is conducted for these three factors.
Future Electricity Structure
Both new lithium-based cells, secondary use lithium-based cells, and LAB use electricity during production, use, and recycling processes. Clean electricity sources like solar and wind can significantly reduce the environmental impact of electricity. China is promoting the development of new energy, leading to a gradual cleaning of the electricity structure, which helps lower the life cycle environmental impacts of cells. Therefore, based on the “China 14th Five-Year Power Development Plan Research” report, future electricity structures are set for 2025, 2035, and 2050, and their impact on the carbon emissions of energy storage cells is assessed.
Results and Discussion
Environmental Impact Results of Energy Storage Cells
Comparison of Environmental Impact Results: The LCA results for the five energy storage cells based on the economic allocation method are presented in Table 3 and Figure 2. LFP cells perform best in terms of environmental impact, while LAB have the highest impact. Specifically, LFP cells slightly exceed SULFP cells only in the HT indicator but outperform other cells in all other indicators, reducing environmental impacts by over 3%. SULFP cells rank second in environmental benefits, with GWP indicator 5% higher than NCM cells but 1% to 61% lower in the other seven indicators. Additionally, SULFP cells outperform SUNCM and LAB in all indicators. NCM and SUNCM cells have mixed performances; NCM cells have 4% to 15% higher ADP, HT, and ODP indicators than SUNCM cells but are 3% to 15% lower in the other five indicators. Overall, the environmental impact potentials from low to high are: LFP, SULFP, NCM, SUNCM, and LAB. This indicates that when considering only environmental impact, LFP cells are more desirable for development.
| Impact Category | Unit | LFP | NCM | SULFP | SUNCM | LAB |
|---|---|---|---|---|---|---|
| ADP | kg Sb eq | 4.37×10⁻⁶ | 1.16×10⁻⁵ | 4.50×10⁻⁶ | 1.11×10⁻⁵ | 3.06×10⁻⁵ |
| ADP-ff | MJ | 2.53 | 3.03 | 3.01 | 3.44 | 7.70 |
| GWP | kg CO₂ eq | 2.78×10⁻¹ | 3.16×10⁻¹ | 3.33×10⁻¹ | 3.69×10⁻¹ | 8.21×10⁻¹ |
| HT | kg 1,4-DB eq | 2.37×10⁻¹ | 4.48×10⁻¹ | 2.24×10⁻¹ | 3.87×10⁻¹ | 5.35×10⁻¹ |
| AP | kg SO₂ eq | 1.39×10⁻³ | 1.82×10⁻³ | 1.56×10⁻³ | 1.88×10⁻³ | 4.00×10⁻³ |
| EP | kg PO₄ eq | 3.21×10⁻⁴ | 4.25×10⁻⁴ | 3.79×10⁻⁴ | 4.80×10⁻⁴ | 8.88×10⁻⁴ |
| ODP | kg CFC-11 eq | 2.50×10⁻⁹ | 6.80×10⁻⁹ | 2.90×10⁻⁹ | 6.11×10⁻⁹ | 8.04×10⁻⁹ |
| PO | kg C₂H₄ eq | 5.38×10⁻⁵ | 7.21×10⁻⁵ | 6.09×10⁻⁵ | 7.50×10⁻⁵ | 1.56×10⁻⁴ |
Due to higher cycle numbers and charge-discharge efficiency, LFP cells deliver more electricity over their life cycle, resulting in the lowest environmental impact. SULFP and NCM cells have similar electricity outputs, leading to comparable environmental impacts. However, NCM cells use significant amounts of rare metals in production, causing higher ADP, HT, and ODP indicators than SULFP cells. SUNCM and LAB, with lower cycle numbers and charge-discharge efficiency, have high environmental impacts. Overall, secondary use cells show potential in alleviating resource shortages but are significantly affected by low cycle numbers and efficiency, requiring further improvement in environmental benefits.
LFP cells demonstrate clear environmental advantages over NCM cells, and SULFP outperforms SUNCM. Moreover, China faces extreme scarcity in key metal resources like nickel, cobalt, and manganese, with import dependencies exceeding 70%, 80%, and 90%, respectively. This不利于 large-scale production of NCM cells. Therefore, LFP cells are more suitable for expanded production, reducing reliance on scarce metals and increasing the proportion of LFP in secondary use cells, thereby lowering the environmental impact of secondary use lithium-based cells.
Additionally, our results differ from some previous studies. For example, discrepancies with Fan et al. and Le Varlet et al. arise from inconsistencies in functional units and system boundaries. Jasper et al. and Yudhistira et al. did not account for differences in charge-discharge efficiency, assuming all cells had the same efficiency, leading to underestimation of environmental impacts for LAB and secondary use cells. This highlights the need for unified functional units and system boundaries, as well as the importance of charge-discharge efficiency in environmental impact assessments, which we explore further below.
Life Cycle Stage Contributions: Figure 3 illustrates the environmental impact contributions of each life cycle stage for the five energy storage cells. Positive values indicate environmental burdens, while negative values represent reduced impacts. The production stage (including production and repurposing) contributes significantly to ADP, HT, and ODP indicators, accounting for 44% to 235%. Due to the use of copper foil, copper, and battery management systems, lithium-based cell production stages contribute highly to ADP and HT indicators. The production processes of these materials consume large amounts of fossil fuels, water, and mineral resources, while releasing heavy metals, dust, and particulate matter harmful to human health. LAB impacts are attributed to lead and copper consumption. Factors affecting ODP include lithium carbonate, graphite, electrolyte, natural gas, and battery management systems, but all five cells have low ODP values, indicating minimal ozone depletion potential.
The use stage dominates ADP-ff, GWP, AP, EP, and PO indicators, contributing 58% to 92%, and also contributes 18% to 58% to HT and ODP indicators. This is due to fossil fuel use in electricity production. Power generation, especially from fossil fuels like coal, natural gas, and oil, not only depletes non-renewable resources but also emits large quantities of greenhouse gases and other pollutants, leading to water eutrophication. Additionally, high cycle numbers and low charge-discharge efficiency result in more electricity output and loss during the use stage, making it the primary contributor in most indicators.
The recycling stage reduces environmental impacts but, due to substantial electricity and natural gas consumption, shows lower reductions in ADP-ff and GWP indicators, only 0.2% to 5.7%. Thanks to the recovery of metals like copper and aluminum and cathode materials, other indicators see reductions of 1.8% to 143.1%, far exceeding ADP-ff and GWP. Furthermore, LAB recycling benefits are much higher than lithium-based cells, attributable to LAB’s more mature recycling industry chain and higher formal recycling rate. In contrast, lithium-based cells have a formal recycling rate only 22% of LAB, indicating a need for improvement in the recycling industry chain. Overall, the use stage has the largest environmental impact, while the recycling stage performs well but requires enhancement in energy use.
Sensitivity Analysis of Influencing Factors
Environmental Impact Allocation Methods: Using the economic allocation method as a baseline, the sensitivity analysis results for allocation methods are shown in Figure 4. The results indicate that the choice of allocation method significantly affects environmental impacts, particularly in ADP, HT, and ODP categories. Under the cut-off allocation method, secondary use products have the lowest environmental impact. Compared to economic allocation, cut-off allocation reduces environmental impacts by 35% to 91% in ADP, HT, and ODP indicators and by over 6% in other indicators. This is because the production and recycling stages contribute significantly to ADP, HT, and ODP indicators. Cut-off allocation attributes all production stage impacts to primary products and all recycling stage benefits to secondary products, making secondary use cells’ environmental impacts lower than new lithium-based cells. Thus, cut-off allocation favors the promotion and development of secondary products.
Conversely, when using the 50/50 allocation method, secondary use lithium-based cells’ environmental impacts exceed those of new lithium-based cells. This method is more suitable for products where secondary use is common. However, the secondary use lithium-based cell market is still emerging, and using 50/50 allocation amplifies the environmental impact of secondary use cells, posing challenges to widespread adoption and appearing unfair. Therefore, assessing product environmental impacts requires careful consideration of market actualities and development stages to ensure accuracy and fairness.
Moreover, since primary use processes deliver less electricity than secondary use processes, physical characteristics allocation has a higher coefficient than 50/50 allocation. However, primary use often occurs in electric vehicles with higher performance demands, leading to faster capacity decay and lower electricity output. Thus, allocating environmental impacts solely based on electricity output from primary and secondary use is unfair. Future work should establish metrics to quantify the value of electricity output in primary and secondary use to optimize allocation ratios.
Analysis of Other Factors: Sensitivity analysis results for battery cycle numbers, charge-discharge efficiency, and formal recycling rate are shown in Figure 5. The results show that battery cycle numbers have relatively low sensitivity, ranging from 6.72% to 24.79%, and decrease further with increasing cycle numbers. Specifically, even a 10% change in cycle life only alters environmental impacts by 0.34% to 1.25%. Compared to cycle numbers, charge-discharge efficiency has higher sensitivity, and sensitivity increases with efficiency improvements. Every 5% increase in charge-discharge efficiency reduces environmental impacts by 18% to 71%, with sensitivity as high as 367% to 1373%. The formal recycling rate has the lowest sensitivity; a 5% increase reduces environmental impacts by only 0.03% to 0.27%, with sensitivity merely 0.63% to 5.45%.
Since the unit environmental impact of the use stage is unaffected by cycle numbers, changes in cycle numbers only affect the unit environmental impacts of production and recycling stages. However, the use stage contributes over 78% to the GWP indicator, resulting in low sensitivity to cycle numbers. In contrast, improving charge-discharge efficiency not only reduces electricity loss in the use stage, directly lowering GWP, but also increases electricity output over the life cycle, reducing unit environmental impacts in production and recycling. Thus, enhancing charge-discharge efficiency significantly affects the full life cycle environmental impact. Changes in the formal recycling rate only influence the average environmental impact of the recycling stage, leading to the lowest sensitivity. In summary, improving charge-discharge efficiency is an effective measure to reduce the environmental impact of energy storage cells.
Future Emission Reduction Potential of Energy Storage Cells
Environmental impact results based on electricity structures for 2021, 2025, 2035, and 2050 are shown in Figure 6. The results indicate that as the electricity structure becomes cleaner, the environmental impacts of cells steadily decrease. Compared to 2021, the electricity structures in 2025, 2035, and 2050 reduce greenhouse gas emissions of the five energy storage cells by 31% to 34%, 52% to 57%, and 72% to 79%, respectively. Notably, the decline in environmental impacts for these cells is slightly lower than the decrease in electricity impact factors but generally consistent. This is because greenhouse gas emissions in the use stage decrease proportionally with the impact factor (coefficient 1), while production and recycling stages also decrease proportionally, though with coefficients less than 1. Since the use stage is the main contributor to the GWP indicator, reducing the electricity impact factor significantly lowers cell environmental impacts. Therefore, cleaning the electricity structure is crucial for improving the full life cycle environmental impact of energy storage cells.
Furthermore, some studies suggest that secondary use cells have lower environmental impacts than new cells, which contradicts our findings. This discrepancy arises from differences in research scenarios; those studies are based on photovoltaic (PV) and energy storage system integration, whereas our study focuses on use-stage electricity from the national grid. In PV-integrated scenarios, the use stage relies entirely on clean energy, resulting in zero emissions, so cell environmental impacts stem only from production and recycling stages. When considering only these two stages in our study, secondary use cells indeed have lower environmental impacts than new cells. Thus, the conclusions are essentially consistent. Overall, integrating PV and other clean energy systems with energy storage systems can reduce use-stage emissions to zero, lowering greenhouse gas emissions of energy storage cells by 78% to 92%, representing an effective measure for promoting low-carbon development of energy storage systems.
Conclusions
Based on the CML-IA baseline method and considering eight environmental impact categories for five energy storage cells, the environmental impact potentials from low to high are: LFP, SULFP, NCM, SUNCM, and LAB. The use stage contributes the most, accounting for 58% to 92% in ADP-ff, GWP, AP, EP, and PO indicators, and 18% to 58% in HT and ODP indicators.
The cut-off allocation method, compared to economic allocation, reduces the environmental impact of secondary use cells by 6% to 91%, favoring the promotion and development of secondary use products. Improving battery charge-discharge efficiency is crucial for reducing greenhouse gas emissions of energy storage cells, with sensitivity exceeding 367%, while battery cycle numbers and formal recycling rates have limited effects, with sensitivity below 25%.
Under the electricity structures of 2025, 2035, and 2050, all five cell types can significantly reduce greenhouse gas emissions by over 31%, 52%, and 72%, respectively, indicating that promoting the cleaning of the electricity structure is essential for lowering the environmental impact of energy storage cells. Additionally, integrating energy storage systems with PV and other clean energy systems is a key emission reduction pathway, capable of reducing full life cycle greenhouse gas emissions by over 78%.
To promote the low-carbon sustainable development of the energy storage cell industry, we recommend prioritizing the development of LFP cells and increasing R&D investment in improving charge-discharge efficiency. Furthermore, advancing the clean transformation of the electricity structure and combining with clean energy systems like PV are critical paths to reduce the environmental impact of energy storage cells.