1. Introduction
In recent years, with the increasing emphasis on environmental protection and the pursuit of sustainable development, the automotive industry has been undergoing a significant transformation. The Chinese government has issued a series of policies to promote the development of new energy vehicles. For example, in October 2021, the State Council’s “Notice on Issuing the Action Plan for Carbon Peaking Before 2030” required that in the transportation industry, green and low-carbon should be one of the key tasks of the industry. It was also clearly stated that by 2030, the proportion of new transportation tools powered by new energy and clean energy would reach about 40%. The General Office of the State Council’s “Notice on Issuing the Development Plan for the New Energy Vehicle Industry (2021 – 2035)” proposed that by 2025, the sales volume of new energy vehicles would reach about 20% of the total sales volume of new cars. Driven by policies and the market, the market share of electric vehicles has increased significantly. As a key component of electric vehicles, the power battery is the guarantee for the sustainable development of electric vehicles. At the same time, the development of electric vehicles will inevitably drive the progress of power batteries. Life cycle assessment (LCA), as a new research tool for carbon footprint tracking and evaluation, can quantitatively analyze the impact on the environment and energy consumption of the research object throughout its life cycle, including raw material acquisition, production and processing of parts, product use, and end-of-life recycling, to achieve the sustainable development of products. This article uses the eFootprint online software system developed in China to establish a life cycle model of lithium-ion power batteries and calculate the LCA results, analyze and evaluate its energy consumption and emissions, and propose corresponding emission reduction measures.
2. Life Cycle Overview
According to the Chinese standard GB/T 24040 – 2008, which is equivalent to the international standard ISO 14040:2006 “Environmental Management – Life Cycle Assessment – Principles and Framework”, life cycle assessment (LCA) is defined as the process of summarizing and evaluating all inputs, outputs, and environmental emissions of the research object throughout its life cycle within the system boundary. LCA evaluation is a quantitative method for the consumption and environmental impact generated during the entire process of a product from cradle to regeneration. When the research object is a power battery, the entire life cycle includes raw material acquisition, monomer battery manufacturing, product use, and recycling after reaching the end-of-life standard. Each of these processes involves energy consumption and environmental pollution emissions. Based on the energy consumption data and pollutant inventory, the environmental impact of the research object will be evaluated according to relevant evaluation indicators, and corresponding energy-saving and emission reduction measures will be proposed. The entire evaluation process includes the following parts: 1) determination of goals and scope; 2) analysis of the inventory of the evaluation object; 3) overall environmental impact assessment; 4) interpretation of the environmental impact results. These parts affect each other, and if a parameter in one part changes, it will affect the final result interpretation. The research framework is shown in Figure 1.
| Process | Description |
|---|---|
| Goal and Scope Definition | Define the purpose, boundaries, and functional units of the LCA study. |
| Inventory Analysis | Collect data on all inputs and outputs of the product system, including energy, materials, and emissions. |
| Impact Assessment | Evaluate the potential environmental impacts of the product system based on the inventory data. |
| Interpretation | Analyze and communicate the results of the LCA study, and identify opportunities for improvement. |
3. Evaluation Tool
This article selects the online LCA analysis software eFootprint developed by Ekotech Environmental Technology Co., Ltd. for the evaluation of lithium-ion power batteries for new energy vehicles. This software is an online LCA data reporting and analysis platform that completes all tasks such as supply chain data survey, database integration, LCA modeling, calculation and analysis, data quality assessment, and LCA result analysis based on the network.
4. Research Object Selection and System Boundary
The research object selected in this article is the lithium iron phosphate battery of BYD’s pure electric vehicle for modeling. The specific parameters are shown in Table 1. To ensure the operability of modeling, the small parts inside the battery that have little impact on the evaluation results have been optimized. The modeling process will be divided into raw material acquisition, manufacturing and assembly, use, and end-of-life recycling stages, and its system boundary is shown in Figure 2.
| Battery Name | Cathode Material | Anode Material | Monomer Voltage | Safety | Energy Density | Cycle Life | Cost |
|---|---|---|---|---|---|---|---|
| Lithium Iron Phosphate | LiFePO4 | Graphite | 3.2V | High | About 125 W – h/kg | About 2300 times | Moderate |
The system boundary includes all the processes and activities related to the life cycle of the LiFePO4 battery, from the extraction of raw materials to the disposal or recycling of the battery at the end of its life. The main processes included in the system boundary are:
- Raw Material Extraction: This includes the extraction of minerals such as lithium, iron, and phosphorus, as well as the production of other materials such as graphite and aluminum used in the battery.
- Battery Manufacturing: The manufacturing process involves the production of battery components such as electrodes, electrolyte, separator, and the assembly of these components into a battery cell.
- Battery Use: This stage includes the use of the battery in an electric vehicle or other applications, including charging and discharging cycles.
- End-of-Life Recycling or Disposal: At the end of its life, the battery can be recycled to recover valuable materials or disposed of in an environmentally friendly manner.
5. Lithium-Ion Power Battery Evaluation Model Construction Checklist
The evaluation model of the lithium iron phosphate battery is constructed for the positive electrode, negative electrode, separator, electrolyte, coolant, and shell, and is divided into raw material acquisition, manufacturing and assembly, use, and end-of-life recycling stages. During the modeling and checklist establishment process, some contents will be slightly adjusted.
5.1 Battery Production Stage
Through literature collection and database invocation, the consumption of each component of the lithium iron phosphate battery is shown in Table 2. With the help of literature, it is known that each kilogram of lithium iron phosphate battery consumes 8.61 MJ of thermal energy and 12.3 kW·h of electrical energy in the production and manufacturing stage. Based on the above values, the research object in this article consumes a total of 4429.38 MJ of thermal energy and 5914.32 kW·h of electrical energy. The electrical energy consumed in the production and assembly stage is about 2.69 MJ/kg, totaling 1298.789 MJ.
| Battery Component | Material | Consumption/kg | Consumption Type | Upstream Source Data |
|---|---|---|---|---|
| Negative Electrode | Graphite | 75.316 | Raw Material/Material | CLCD – China – ECER 0.8 |
| Aluminum | 60.451 | Raw Material/Material | Ecoinvent 3.1.0 | |
| Lithium Hexafluorophosphate | 4.856 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Water | 1.338 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Positive Electrode | Oxalic Acid Iron | 114.956 | Raw Material/Material | CLCD – China – ECER 0.8 |
| Lithium Carbonate | Raw Material/Material | Ecoinvent 3.1.0 | ||
| Lithium Iron Phosphate Dihydrogen Phosphate | Raw Material/Material | Ecoinvent 3.1.0 | ||
| Carbon Black | Raw Material/Material | CLCD – China – ECER 0.8 | ||
| Aluminum Foil | 98.109 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| PVDH | 5.054 | Raw Material/Material | Ecoinvent 3.1.0 | |
| Lithium Carbonate | 3.221 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Oxalic Acid Iron | 2.131 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Water | 1.635 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Electrolyte | Lithium Hexafluorophosphate | 13.379 | Raw Material/Material | CLCD – China – ECER 0.8 |
| Ethylene Carbonate | 38.649 | Raw Material/Material | Ecoinvent 3.1.0 | |
| Dimethyl Ester | 38.649 | Raw Material/Material | Ecoinvent 3.1.0 | |
| Separator | Polypropylene | 9.415 | Raw Material/Material | Ecoinvent 3.1.0 |
| Polyethylene | 1.487 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Shell | Polypropylene | 6.442 | Raw Material/Material | CLCD – China – ECER 0.8 |
| Steel | 7.433 | Raw Material/Material | Ecoinvent 3.1.0 | |
| Glass Fiber | 1.487 | Raw Material/Material | CLCD – China – ECER 0.8 | |
| Coolant | Ethylene Glycol | 4.955 | Raw Material/Material | CLCD – China – ECER 0.8 |
5.2 Battery Use Stage
In this study, the energy consumption in the use stage includes two parts: one is the energy E1 required by the power battery during driving, and the other is the energy loss E2 other than the effective efficiency during the charging and discharging process. The formulas for calculating E1 and E2 are as follows:
E1 = 30% ✖ Mb/Mv ✖ Db ✖ Eb/φ
E2 = Db ✖ Eb ✖ (1-φ)
where is the weight of the battery system (kg), Mv represents the total mass of the vehicle (kg), Db represents the total mileage that can be used in the life cycle (km), Eb is the power consumption per unit distance of the battery (kW·h/km), and φ is the charging and discharging effective efficiency (%) of the battery.
Taking the actual vehicle battery as the benchmark, the battery capacity is set to 60.48 kW·h. The functional unit of the operation and use stage is selected as 200,000 km. It is considered that the power consumption of the electric vehicle in the use stage is linearly related to the mass of the whole vehicle. The power consumption per 100 km of the vehicle given by the Ministry of Industry and Information Technology is 11.81 kW·h. The modeling process fully considers the charging and discharging efficiency and the service life of the battery, and estimates that the charging and discharging effective efficiency is 90.1%. The power consumption of the lithium iron phosphate battery in the entire life cycle of the use stage is calculated to be 26322.22 kW·h.
5.3 Battery Recycling Stage
The positive electrode, electrolyte, and negative electrode of the lithium iron phosphate battery contain relevant chemically active materials, and also have certain corrosiveness and environmental unfriendliness, and should be recycled in a timely manner to avoid polluting the external environment. At present, the main recycling methods for end-of-life batteries are hydrometallurgical and pyrometallurgical recycling. In this article, according to its structural characteristics, the hydrometallurgical recycling method will be adopted, mainly recovering the metal materials in the positive electrode. The quality of the electrolyte decreases after long-term use, and the material recovery rate of other components is low and difficult to recycle. Therefore, the above components will be ignored in this article, and the recovery rate of the positive electrode material is set to 90%. The material list required for recycling 1 kW·h of this battery is shown in Table 3.
| Quantity | Unit | Recycling Material |
|---|---|---|
| 0.045 | kg | Natural Gas |
| 0.36 | kg | Sodium Hydroxide |
| 0.615 | kg | Ammonium Hydroxide |
| 5.15 | kg | Concentrated Water |
| 4.94 | kg | Hydrochloric Acid |
6. LCA Evaluation Result Analysis
6.1 Evaluation Indicators
A total of 8 environmental impact indicators are selected in this article for the green and sustainable evaluation of the lithium iron phosphate power battery throughout its life cycle. Among them, the indicators used to evaluate sustainability include global warming potential (GWP), primary energy consumption (PED), water resource consumption (WU), abiotic resource consumption (ADP), and ozone layer depletion (ODP); the indicators used to evaluate greenness include acidification potential (AP), eutrophication potential (EP), and respirable inorganic matter (RI).
6.2 Evaluation Results
Through the previous collection and collation of lithium iron phosphate data lists, a life cycle model was established using LCA software, and 1 item of lithium iron phosphate battery was modeled and calculated on eFootprint. The LCA data analysis list results are obtained. Table 4 shows the LCA indicator results of the lithium iron phosphate battery (1 item), Table 5 shows the indicator results of the lithium iron phosphate battery (production stage) (1 item), and Table 6 shows the indicator results of the lithium iron phosphate battery (end-of-life stage) (1 item).
| Environmental Impact Type Indicator | Impact Type Indicator Unit | LCA Result | Uncertainty |
|---|---|---|---|
| Climate Change (GWP) | kg CO2 eq | 7.27E – 02 | 0.99% |
| Primary Energy Consumption (PED) | MJ | 1.24E + 00 | 1.09% |
| Non – biotic Resource Consumption Potential (ADP) | kg antimony eq | 4.63E – 06 | 6.19% |
| Water Resource Consumption (WU) | kg | 1.10E + 00 | 2.38% |
| Acidification (AP) | kg SO2 eq | 2.74E – 04 | 0.49% |
| Eutrophication Potential (EP) | kg PO43 – eq | 5.47E – 05 | 0.31% |
| Respirable Inorganic Matter (RI) | kg PM2.5 eq | 9.33E – 05 | 1.65% |
| Ozone Layer Depletion (ODP) | kg CFC – 11 eq | 2.92E – 09 | 3.33% |
| Process Name | GWP | PED | ADP | WU | AP | EP | RI | ODP |
|---|---|---|---|---|---|---|---|---|
| Positive Electrode | 3.95e – 2 | 6.55e – 1 | 3.95e – 7 | 4.06 – 1 | 1.58e – 4 | 3.76e – 5 | 3.98e – 5 | 1.62e – 9 |
| Negative Electrode | 8.87e – 3 | 1.73e – 1 | 4.08e – 6 | 3.87e – 1 | 1.36e – 5 | 5.26e – 6 | 1.17e – 5 | 1.28e – 9 |
| Electrolyte | 4.68e – 3 | 1.01e – 1 | 6.43e – 9 | 7.26e – 2 | 8.00e – 6 | 1.41e – 6 | 2.00e – 5 | 7.88e – 9 |
| Separator | 3.49e – 3 | 8.22e – 2 | 2.37e – 8 | 1.20e – 2 | 1.11e – 5 | 1.06e – 6 | 5.12e – 6 | 0.99e – 9 |
| Process Name | GWP | PED | ADP | WU | AP | EP | RI | ODP |
|---|---|---|---|---|---|---|---|---|
| End – of – life Lithium Iron Phosphate Monomer Battery | 3.89e3 | 5.53e4 | 4.65e – 1 | 5.57e4 | 1.86e1 | 2.24e0 | 2.24e1 | 3.22e – 3 |
7. LCA Result Analysis
7.1 Energy Consumption Analysis and Evaluation
From the above indicator results, it can be found that in the production stage of the lithium iron phosphate battery, the component with the largest energy consumption contribution is the battery positive electrode, and the energy consumption contribution of the lithium-ion active material inside is the largest. It can be concluded that in the battery production process, the substances related to lithium iron phosphate in the positive electrode contribute the most to the LCA results, mainly because of the consumption of crude oil and coal in the raw material acquisition stage. In the battery production and assembly process, the processes with the largest energy consumption contributions are the formation and drying of the battery, which mainly consume thermal energy and electrical energy. It is calculated that about 0.42 MJ of electrical energy and 0.49 MJ of thermal energy are consumed per kilogram of monomer battery production. In the assembly process, about 2.18 MJ of electrical energy and 2.42 MJ of thermal energy are consumed per kilogram of monomer battery. Inside the battery composition, the acquisition of raw material aluminum consumes a large amount of energy, and in the battery system, there is a relatively large amount of aluminum material, accounting for about 35% of the total battery mass. It takes 432 MJ of energy to produce 1 kg of aluminum. In the use stage, the direct energy consumption of the power battery is electrical energy, and its functional unit energy consumption in the use stage can be calculated as 0.189 MJ/km.
7.2 Emission Analysis and Evaluation
In the production stage, the stage with the most emissions in the lithium iron phosphate battery is the shell production, followed by the positive electrode production and negative electrode production. During the production of the battery shell, there are more particulate matters, which are mainly caused by the production process of the raw material aluminum. At present, China produces Al2O3 through the combined method and sintering method, resulting in more particulate matter, dust, and other pollutants. In the use stage, due to the production of electrical energy, nitrogen oxides, sulfur oxides, PM10, PM2.5, etc. are the main emission pollutants.
8. Conclusion
Through the above analysis, the life cycle assessment results of lithium iron phosphate can be improved and waste emissions can be reduced through the following two means.
8.1 Improving the Preparation Process of Lithium Iron Phosphate
By controlling the sintering process to optimize and improve the compaction density and using lithium compensation technology to improve the cycle performance, a positive electrode material with high capacity, high compaction, and good electrochemical performance can be obtained. In the mixing and ball milling processes, ethanol or pure water can be used as the ball milling agent, and the conductive performance can be improved by using small particle sizes, carbon coating, and adding nanotubes.
8.2 Changing the Power Production Structure
By developing and applying new power production technologies and clean energy and reducing the utilization rate of thermal power generation, the emission of pollutants into the air environment can be reduced.
In summary, through the comprehensive life cycle assessment of the lithium iron phosphate battery, it is possible to identify the key factors affecting energy consumption and emissions in each stage, and then take corresponding improvement measures to promote the green and sustainable development of the lithium iron phosphate battery and contribute to the development of the new energy vehicle industry and environmental protection. Future research can focus on further optimizing the production process and recycling technology of lithium iron phosphate batteries, as well as exploring the application and combination of more clean energy sources to continuously reduce the environmental impact of lithium iron phosphate batteries throughout their life cycle.