Comparison of three typical lithium-ion batteries for pure electric vehicles from the perspective of life cycle assessment

Abstract

In the previous study, environmental impacts of lithium-ion batteries (LIBs) have become a concern due the large-scale production and application. The present paper aims to quantify the potential environmental impacts of LIBs in terms of life cycle assessment. Three different batteries are compared in this study: lithium iron phosphate (LFP) batteries, lithium nickel cobalt manganese oxide (NCM) 811 batteries and NCM622 batteries. The results show that the environmental impacts caused by LIBs are mainly reflected in five aspects from eleven evaluation indexes: Abiotic depletion (fossil fuels), Global warming, Human toxicity potential (HTP), Freshwater ecotoxicity potential (FETP) and Marine ecotoxicity potential (METP). The production phase and assembly phase of LIBs are the main sources of Greenhouse gas (GHG) emission, the GHG emissions of NCM622 battery is 156.73 kg CO₂-eq/kWh, which accounts for 35.40% of the total GHG emissions. The study shows that the hydrometallurgy method in the recycling phase may not always be environmentally friendly for NCM batteries, it can increase the indicators of HTP, FETP and METP. The precursor materials in NCM batteries and the electricity consumption of LFP batteries are sensitive factors to environmental impacts, which can be effectively improved by improving the process and optimizing the electricity mixes. Suggestions for process optimization of China’s LIBs industry are proposed based on the future electricity mixes.

Graphical abstract

Introduction

In recent years, China is the leading producer of lithium-ion batteries (LIBs), which rely on essential components such as lithium, cobalt and graphite. The number of battery electric vehicles (BEVs) on the road is predicted to reach over 130 million globally by 2030 (Kapustin and Grushevenko 2020). The requirement for LIBs is anticipated to increase significantly, with an estimated global demand of 9300 GWh by 2030 (Lai, Chen et al. 2022). This growth in the BEV market is expected to be driven largely by China, which in the near future will have significant impacts on the production and the disposal of LIBs. China’s regulations on lithium waste are also being updated in response to the rapid updating of electronics. China faces greater energy pressure compared to developed countries in particularly (Chen, Lai et al. 2022a, b). Therefore, it is critical to accurately estimate the life cycle resource consumption of various LIBs in China to mitigate potential environmental pressures.

Promoting BEVs will help to solve our nation’s problem with energy security (Haustein and Jensen 2018). BEVs use a variety of chemistries and battery architectures, including Li-ion, nickel metal hydride and sodium-nickel chloride (Asef, Milan et al. 2021). At the same time, the advancement of battery technology and commercial potential suggests that LIBs are better option for the growth of the BEVs industry due to their technological maturity and lower manufacturing costs (Diaz-Ramirez, Ferreira et al. 2020). In both mobile and permanent energy storage systems, LIBs are regarded as a crucial component to assist in lowering harmful emissions from the transportation sector by enabling electric mobility (Tourlomousis and Chang 2017).

Currently, there are various types of LIBs available, with lithium iron phosphate (LFP) batteries and lithium nickel cobalt manganese oxide (NCM) batteries being used extensively in BEVs (Shu et al. 2021). In the context of electric passenger vehicles, the predominant LIB chemistry used in China is NCM 622 battery, although there are other types such as NCM 111 and NCM 811 available (Yang, Mu et al. 2020). However, the production and application of these batteries have the potential to emit greenhouse gas (GHG) and environmental damage during their whole life cycle (Manh-Kien, Mevawala et al. 2020). One promising strategy for reducing the environmental impacts of LIBs is secondary use, which can delay disposal and provide commercial and environmental benefits (Ahmadi et al. 2015). It is important to examine environmental effects across entire life cycle, including long lifespan and multiple stages (Kelly et al. 2020).

Additionally, the environmental impacts of LIBs varies depending on the use of various materials, industrial procedures, manufacturing strategies and recycling methods (Du et al. 2017). Du et al. selected 7 distribution methods to study the production and recycling of LIB on the basis of the same data, and proposed that the recycling of lithium-ion batteries must consider the influence of modeling methods and distribution methods (Du et al. 2022a, b). To meet the demands of the LIBs industry, new cathode materials with greater density of energy and capacity are constantly being created (Wang, Wu et al. 2019a, 2019b). Currently, LFP is used as the positive electrode in LFP batteries, while the positive electrodes of NCM batteries consist of nickel, cobalt, and aluminum (Yang et al. 2021). Nevertheless, there is a persistent effort to develop cathode materials with greater energy density and capacity to meet the requirements of LIBs (Chakraborty, Banerjee et al. 2018).

There has been considerable attention given to conducting life cycle assessment (LCA) research on LIBs in recent years, particularly in terms of the resource utilization and environmental impacts (Liu, Liu et al. 2021). However, many studies have mainly focused on the production phase of the battery and have not taken into account the potential impacts of recycling phase (Nordelof et al. 2016). Additionally, few studies have investigated the overall environmental impacts of LIBs throughout the entire life cycle (Wang, Deng et al. 2020). Instead, most of the available research have concentrated on a single stage of the life cycle. For example, some studies have examined the environmental impacts of NCM batteries, indicating that the material development phase contributes the most to energy utilization, potential for global warming and acidification (Sun, Luo et al. 2020). The production of NCM111 batteries, which involves cathode materials and aluminum manufacturing has been identified as a primary source of contamination by researchers (Dai, Kelly et al. 2019).

Scholars have also studied the environmental effects of various LIBs. MajeauBettez et al. assessed the environmental impacts of NCM batteries, NiMH batteries and LFP batteries during the manufacturing process and found that NiMH batteries posed the greatest environmental load (Majeau-Bettez et al. 2011). Smith et al. proved that solid-state batteries exhibit lower carbon emissions than LIBs during the manufacturing stage (Smith, Ibn-Mohammed et al. 2021). Oliveira et al. used SimaPro software to evaluate several environmental variables of the LMO batteries and LFP batteries (Oliveira et al. 2015). Besides, several studies examining the environmental effects of LIBs from other angles. For instance, Zackrisson et al. assessed the effect of LFP batteries produced using various solvents on the environment, which revealing that water exhibits superior performance than N-methyl-2-pyrrolidone (NMP) (Zackrisson et al. 2010). While numerous research have looked into the effects on the environment of LIBs, less focus has been placed on the long-term environmental impacts of different types of LIBs throughout their life cycles.

The LCA method is employed in this studies to quantify possible environmental impacts of three typical batteries, namely LFP batteries, NCM 811 batteries and NCM622 batteries. This methodology comprehensively evaluates the environmental hotpots, which describes a technique for systematic analysis used to quantify the collection of raw materials, manufacturing, use of resources, transportation, disposal and any potential environmental effects from recycling (Arshad, Lin et al. 2022). Energy consumption is calculated based on battery capacity decay and cycle life during the use phase. The potential contributions of this article are as follows:

• (1) The “cradle-to-grave” LCA is conducted for three typical LIBs in China, providing a complete and transparent life cycle list for all life cycle stages and understand which LIBs are more environmentally friendly for BEVs.

• (2) Through sensitivity analysis to evaluation indicators that have great influence for LIBs on the environmental impacts. Besides, the GHG emissions of the current and future LIBs production are calculated under hybrid energy structure.

• (3) Further exploring the environmental performance of the recycling processes for LFP and NCM batteries, providing technical support for related green manufacturing and full life cycle management.

Methodology

The LCA technique is employed to the extent of ISO 14040–14044 standards to analyze the whole life cycle of the product, process, service or activity, and estimates its environmental effects in a quantitative manner (Daniele Landi 2022). The models are developed by SimaPro 9.0 software, which integrates the Ecoinvent 3.0 database (Suh et al. 2016) and provides midpoint and endpoint impact assessment methods, such as Eco-indicator 99, Impact 2002+, CML IA and ReCiPe to analyze the environmental impacts. Each of method includes several categories of effects, such as climate change and acidification which are widely used in LCA. In this study, the CML-IA v3.05 method (Silvestri, Forcina et al. 2020) is used to assess the environmental impacts. The evaluation will strictly adhere to the international standard ISO 14044 to ensure the accuracy of the findings (Hua, Zhou et al. 2020).

Goal and scope

As shown in Fig. 1, scope of “cradle-to-grave” is employed in this study to evaluate the environmental effects of three types of LIBs, considering battery recycling and utilization. The performance parameters of the three battery systems are shown in Table 1. The power capacity of the LFP battery system is almost identical to the NCM battery system. The energy density of LFP battery is 121 Wh/kg, the energy density of NCM622 battery is 149 Wh/kg, and NCM811 battery have an energy density of 154 Wh/kg. In this study, the total mass of key components of the battery is calculated by setting the mass of 1 kWh LFP battery pack at 7.49 kg, the 1 kWh NCM622 battery pack at 5.76 kg, and 1 kWh NCM 811 battery pack at 5.33 kg.

Fig. 1

The battery’s system boundaries during its entire life cycle

Table 1 The performance parameters of the three battery systems

The functional unit (FU) is established as the rated capacity of 1 kWh battery pack, which is commonly utilized unit in previous LCA studies. To make the environmental effects of various batteries comparable, all the gathered data must be converted to FU (Wu et al. 2021). The LIB is made up of the single cell, shell, wire and battery management system. The cathode, anode, electrolyte and diaphragm are the four most crucial components of the LIB used in BEVs (Tian, Qin et al. 2020). The weight of the NCM622 battery is 161.3 kg, the overall mass of the LFP battery is 209.7 kg, and the total mass of the NCM811 battery is 149.2 kg. Table 2 shows the mass ratios of different components of three types of batteries.

Table 2 The mass ratios of different components of three types of batteries

The system boundary is shown in Fig. 2, which includes the raw material extraction, component production, battery manufacturing, transportation, use and end of life stage. The battery production phase requires the preparation of raw materials, including the production of cathode materials and the refining of lithium. Then the battery cells, copper rods, battery management system, etc. are assembled to form the battery system. This process includes winding, cutting, winding shaping, laminating, and other processes (Wang, Yu et al. 2019a, 2019b). The transportation stage includes the transport of raw materials from the origin to the manufacturing factory and the transport of used batteries from the collection center to the recycling plant. According to (Zackrisson et al. 2016), it can be assumed that a common waste battery collection center is 500 km away from the recycling plant in the European context. The same assumption is made for the average distance between Chinese cities. Truck transportation is the primary means of transportation.

Fig. 2

System boundaries of a LFP batteries and b NCM batteries

The energy consumption in the use stage is mainly caused by the decrease in charge and discharge efficiency and quality loss (Pellow, Ambrose et al. 2020). Meanwhile, the charge and discharge efficiency of the battery will decrease with the increase in the number of cycles (Picatoste, Justel et al. 2022). The total driving distance (L) of the electric vehicle in the use phase is expressed with the initial driving distance per charge (D₀), the capacity decay rate (r) and the number of cycles (c). The total driving distance (L) of the BEVs in the use phase is defined as follows (Deng et al. 2019):

$$L = D_{0} \times \left( {c - \frac{{rc^{2} }}{2}} \right)$$

(1)

The total energy consumption (E) in the use stage is related to factors such as battery efficiency ($\eta_{{{\text{battery}}}}$), battery charging efficiency ($\eta_{{{\text{charger}}}}$), discharged energy ($E_{{{\text{discharged}}}}$), and total driving distance (L). To simplify the study, it is assumed that the charge and discharge efficiency in the use stage is 80% and will not decrease with the increase of the number of cycles. The total energy consumption in the use stage is expressed as follows (Deng et al. 2019):

$$E = L \times \frac{{E_{{{\text{discharged}}}} }}{{D\eta_{{{\text{battery}}}} \eta_{{{\text{charger}}}} }}$$

(2)

The mainstream process of recycling LIBs in Chinese enterprises is hydrometallurgy method, which has the characteristics of low energy consumption, high recovery rate and relatively mature process (Du et al. 2022a, b). The hydrometallurgical process can be divided into three different steps: Pretreatment, leaching and metal recovery. After the battery is discharged, disassembled and crushed, the final product is obtained by hydrometallurgical technology through low temperature leaching, purification and separation. The hydrometallurgy recycling method is used in this research. The production and recycling of other electric vehicle components are not considered in this study.

Life cycle inventory

Life cycle inventory (LCI) analysis is the crucial step in constructing an input and output list for a product system to analyze its environmental impacts (Qiao et al. 2017). LCI data can be obtained directly through experimentation (Bobba et al. 2018), cooperation with companies (Koroma, Costa et al. 2021), indirectly through sources of literature, LCA software and databases (Wernet et al. 2016). To ensure data completeness and representation, we have conducted a field survey of three leading LIB factories and two recycling enterprises in China to collect primary LCI data. The data used in this study are mainly from technical data sheets and literature readings (Sun et al. 2017). Ecoinvent 3.0 database has supplemented the inventory data. Data sources for three types of LIBs are listed in Table 3, and the detailed date list of three types of LIBs can be found in Tables 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18.

Table 3 Data sources for three types of LIBs

Cathode material is an important part of LIBs, which directly determined its energy density and service life. The cathode material of 1 kWh NCM811 battery is 1.63 kg, accounting for 26.3% of the total material input. The cathode material of 1 kWh NCM622 battery is 1.77 kg, accounting for 26.8% of the total material input. The cathode material of NCM battery is mainly obtained by hydrothermal method from ternary precursor and lithium hydroxide (LiOH), in which LiOH derives from lithium ore (Soge, Willoughby et al. 2021). The cathode material of 1 kWh LFP battery is 2.11 kg, accounting for 25.2% of the total input material. The cathode material of LFP battery is mainly obtained by ferric sulfate, LiOH and phosphoric acid (H₃PO₄) under constant temperature condition. The anode material is graphite. The selected binder material is polyvinylidene fluoride (PVDF). The electrolyte consisted of lithium hexafluorophosphate (LiPF₆) and ethylene carbonate (EC). The main component of the shell is aluminum. Cathode collector has the function of loop formation and stable control performance. Aluminum foil is used for cathode collector. Anode collector is made of copper foil by pyrometallurgy.

The molded cathode and anode materials are coated, dried and rolled. The energy consumption in the battery assembly stage is shown in Table 4, among which the energy consumption in the drying stage accounts for the largest proportion. The transportation phase is carried by truck, and the study assumes that the transport distance is 500 km. In the context of this study, considering the capacity of 28 kWh LIBs with efficiency of 80% are used for 2500 days in BEVs. The modeling information mainly refers to the battery cycle number and capacity fade experiment of BEVs (Dong, Fu et al. 2020).

Table 4 Energy consumption of three batteries assembly in China (Lai, Gu et al. 2022)

Life cycle impact assessment

Due to the fact that LIBs have become the growing issue in recent years, the assessment of its environmental impacts on the whole life cycle is helpful to provide the LIBs industries with an appropriate reference value. The production of LIBs is a complicated process that uses resources, produces waste and releases different exhaust gases. Based on the above methods, this study uses SimaPro 9.0 software to construct the LCA model. To fully assess the environmental effects of LIBs, the CML-IA v3.05 (Silvestri, Forcina et al. 2020) is used to assess the impact of the three types of battery systems on the environment.

Interpretation

By life cycle interpretation, the primary contributing factors and essential components of LIBs are discovered. The environmental indexes of CML-IA method are discussed: Abiotic depletion (AD), Abiotic depletion (fossil fuels) (ADF), Global warming (GWP), Ozone layer depletion (ODP), Human toxicity potential (HTP), Freshwater ecotoxicity potential (FETP), Marine ecotoxicity potential (METP), Terrestrial ecotoxicity potential (TETP), Photochemical ozone creation potential (POCP), Acidification potential (AP) and Eutrophication potential (EP). The sensitivity analysis is carried out to identify the most sensitive substances to environmental impacts. By quantifying the energy consumption in the production phase, the change in environmental indicators caused by the increase of 10% in the baseline case is explored. Besides, this paper creates the scenario analysis based on the future electricity mixes to provide reference for realizing the China’s carbon peaking and carbon neutrality goals.

Results and discussion

Life cycle assessment results

Table 5 displays the comparison of 11 ecological indicators across the entire life cycle of three types of LIBs, which highlights the major contributing processes of the production phase and assembly phase. The transportation process is the major contributor to METP, GWP and ADF. Furthermore, the LFP batteries consume more energy than the NCM batteries. This is because the energy density of LFP batteries is lower than NCM batteries, which consumes more energy during the transport phase. As the development of LIBs moves toward high nickel content, it is important to consider the ecological indexes of AP and POCP, this is because the preparation of raw materials for ternary precursors, such as nickel sulfate (NiSO₄) and cobalt sulfate (CoSO₄), involves the use of concentrated sulfuric acid. The reaction of concentrated sulfuric acid results in the production of SO₂, and NiSO₄ can be used as catalyst to improve the rate and efficiency of hydrogenation and oxidation reactions, which are the main component affecting AP and POCP. The EP of LFP batteries is higher than NCM622 and NCM811 batteries. This is because the primary raw material for the positive electrode generates ammonium-containing waste liquid during the production phase. Besides, in the case of LFP battery systems, almost all ADF and TETP occur during the use phase and the GHG emissions in the assembly stage is higher than the production stage, where the main energy is electricity.

Table 5 LCA results of 1 kWh LFP batteries, NCM622 batteries and NCM811 batteries (CML-IA)

The LCA findings reveal that the environmental impacts caused by LIBs is mainly reflected in five aspects from eleven evaluation indexes: HTP, FETP, GWP, ADF and METP. The three LIBs have the most substantial environmental contamination during the production phase of the five stages, which is followed by the use phase, assembly phase and transport phase. In addition, the study shows that the hydrometallurgy recycling of LFP batteries can effectively relieve the environmental impacts. As for the NCM622 batteries and NCM811 batteries, the hydrometallurgy recycling results in greater HTP, FETP and METP. The main reason is that NCM batteries contain heavy metals, during the recycling phase, toxic and harmful metal elements and substances can cause pollution to human health and the environment. This proved that the recycling stage is not always a stage of offsetting environmental pollution.

The research finding reveals that NCM622 batteries have higher GHG emissions than NCM811 batteries, as demonstrated by Fig. 3. In contrast, LFP batteries exhibit significantly lower GHG emissions at 136.79 kg CO₂-eq/kWh, indicating that Prioritizing LFP battery utilization can effectively cut GHG emissions. Moreover, the study founds the GHG emissions contribution of various components in the production of LIBs. The results indicate that the assembly of NCM811 batteries resulted in GHG emissions of 47.21 kg CO₂-eq/kWh, accounting for 31.63% of the total GHG emissions. Notably, the production phase and assembly phase are the primary contributors to GHG emissions across all phases of LIBs. The main reason is that the precursor of NCM batteries require heavy metal salts such as NiSO₄ and CoSO₄ will generate a large amount of GHG. The main energy consumed during the battery assembly stage is electricity.

Fig. 3

GHG emissions at five stages of LIBs

To ensure the accuracy of the experimental results, we compare the GHG emissions with previous studies in Fig. 4. The GHG emissions of different LIBs are significantly different, ranging from 49 to 124 kg CO₂-eq/kWh. In this research, the GHG emissions of NCM811 battery during assembly are 47.52 kg CO₂-eq/kWh. This is because NCM811 battery have higher nickel content, which requires more energy to extract and process than cobalt and manganese. The difference in the GHG emissions during battery assembly phase is mainly due to difference in grid structure. The difference in the GHG emissions of the rest of the battery is due to the difference in the background data source and the choice of production equipment. As shown in Fig. 4, GHG results in the production stage are in the middle of literature estimates.

Fig. 4

Comparison of GHG emissions in the battery production phase

Abiotic Depletion (ADP fossil) (ADF) is an evaluation index to measure the consumption of fossil energy (Yang, Lan et al. 2022). Figure 5 shows the ADF values for the three types of LIBs. Compared with LFP batteries, NCM811 and NCM622 batteries produce more severe ADF burden. The ADF of LIBs is mainly produced in the battery production, assembly and use stage. This is because the battery production and assembly stages consume huge amounts of energy, such as coal, oil and electricity to make metals such as steel, lithium and cobalt. Besides, coal power is still the main way used in China.

Fig. 5

ADF of three types of batteries during battery entire life cycle

Human toxicity potential (HTP) is an evaluation index that measures how hazardous substances affect the human body (Smith et al. 2020). Figure 6 shows the HTP values for the three types of LIBs. The production phase is the main source of HTP for NCM622 and NCM811 batteries, the HTP of NCM battery mainly comes from the thermal radiation produced by the heavy metal in the cathode and aluminum shell. On the other hand, the HTP of LFP batteries mainly comes from the assembly phase, because the thermal radiation comes from energy consumption, it is dominated by electricity.

Fig. 6

HTP of three types of batteries during battery entire life cycle

Marine ecotoxicity potential (METP) refers to the adverse effects of toxic chemical emissions on marine ecosystems, including the accumulation and discharge of substances like mercury, copper, lead and radioactive elements (Jackson et al. 2016). Figure 7 illustrates the METP impact of three types of LIBs. The results reveal that the highest METP impact is during the production and assembly stages of cathode materials. This is due to the presence of heavy metal pollutants in cathode production and toxic pollutants produced during the assembly stage. The precursor of the NCM battery contains heavy metals such as nickel, cobalt and manganese. At the same time, during the production process, the LIBs will produce waste water, which may contain heavy metals, organic substance, acid and alkali and other harmful substances, causing certain pollution to the soil and water resources.

Fig. 7

METP of the entire life cycle for three LIBs

As shown in Fig. 7, negative values represent existence of enviromental benefits under corresponding impact category. During the recycling stage, the environmental benefit of LFP batteries is higher than NCM batteries. The main reason is that the hydrometallurgical recycling Li, Fe and Al from the spent LFP batteries can alleviate the METP. Pyrolysis is considered as an alternative recovery method to pretreatment, which can decompose organic substances such as PVDF under high temperature conditions and facilitate subsequent hydrometallurgical processes. However, the pyrolysis separation electrode may affect the recycling of materials and produce wastewater.

Freshwater ecotoxicity potential (FETP) is a measure of the impact of pollutants on freshwater ecology. It refers to the interdependent relationship between all biological communities and physical and chemical environment within the given water area, formed through the cycling of substances (Aurisano, Albizzati et al. 2019). Figure 8 presents the FETP impact of three types of LIBs. The causes of FETP during the battery “Production stage” are consistent with those of METP, which involve the presence of heavy metal pollutants and toxic substances.

Fig. 8

FETP of the entire life cycle for three LIBs

Sensitivity analysis

The sensitivity analysis highlights that the production stage of LIBs materials has the most significant impact on environmental sustainability, particularly for cathode materials. To ensure the accuracy of the model, expert consultation is utilized to assume that the cathode active material’s mass and battery energy density remain unchanged despite variations in the material’s chemical properties. By analyzing the sensitivities of LFP batteries and NCM batteries over their life cycles, identifying the key parameters that have high sensitivity and impact the model output.

In this study, the 10% floating interval is used to quantify the battery input and present the results in Fig. 9 and Fig. 10. For LFP batteries, eight sensitive parameters are selected according to the floating ratio of environmental indicators by quantifying input list, namely NMP, electricity, glucose, H₃PO₄, ethylene carbonate, lithium chloride, aluminum ingot, and battery separator. For NCM622 and NCM811 batteries, eight sensitive parameters are selected according to the floating ratio of environmental indicators, namely electricity, lithium carbonate (Li₂CO₃), aluminum, oxygen, sodium hydroxide (NaOH), sheet rolling, battery separator and NiSO₄, among which input of nickel sulfate is the key parameter in the production stage. The findings reveal that electricity is the most sensitive factor throughout the entire life cycle of LFP batteries. For NCM batteries, the precursor material in the cathode material is identified as the most sensitive factor. This is because increasing the NiSO₄ content during the production of precursor material will lead to higher consumption of steam, LiOH and oxygen.

Fig. 9

Sensitivity analysis diagram of LFP battery

Fig. 10

Sensitivity analysis diagram of NCM battery

Scenario analysis

Table 6 indicates the main sources for electricity production in the next 30 years in China, which are thermal power (67.9%), hydropower (17.0%), wind power (6.0%), nuclear power (5.6%) and photovoltaic power (3.5%) in 2020 (CEC 2021). In particular, coal plays a dominant role in thermal power. Consequently, the authors assume that thermal power is completely fueled by coal. The energy consumption and environmental emissions are calculated using the ecoinvent 3.0 database. It is predicted that wind power and photovoltaic power will be the main power generation methods in China by 2050. As demonstrated in Fig. 11, the study reveals that wind power has the greatest potential for reducing greenhouse gas emissions. Besides, increasing the proportion of clean energy sources in the production of LFP batteries can effectively mitigate environmental impacts, especially for METP and GWP. The study has found that TETP did not change significantly as the proportion of clean energy increased, this is because during the construction of power stations, the surface environment is destroyed and reformed, involving the emission of carbon dioxide, methane and other gases buried below the surface.

Table 6 Electricity mix in the next 30 years in China

Fig. 11

The power optimization diagram of LFP battery

Currently, various methods are used to prepare cathode materials for NCM batteries, such as coprecipitation, hydrothermal, sol–gel, solid phase and combustion methods. The coprecipitation method involves dissolving the metal salt solution with nickel, cobalt and manganese, precipitating each component according to the stoichiometric ratio, and obtaining the precursor through extraction and filtration treatment. The precursor is transformed into the ternary cathode material through high-temperature burning. In this study, the sol–gel method is employed to prepare the positive electrode material of ternary lithium battery, using lithium acetate, nickel acetate, manganese acetate and acetic acid as raw materials. The optimization diagram of the two ternary lithium batteries are shown in Fig. 12. The results indicates that the sol–gel method has significant reduction in five environmental impacts indexes, including AD, POCP, AP, FETP and HTP.

Fig. 12

Percentage diagram of material optimization for NCM battery precursors

Conclusions

In this paper, the material consumption and energy input lists of three LIBs used in BEVs are collected and sorted out. The life cycle resource consumption index and environmental impact index of LFP, NCM622 and NCM811 batteries are calculated by using the SimaPro software and CML-IA method. The main conclusions are summarized as follows:

• 1 The environmental impacts of three types of LIBs are mainly generated in the production and assembly stage, followed by the use stage. The production phase and assembly phase of LIBs are the main sources of GHG emission, the GHG emissions of NCM622 battery is 156.73 kg CO2-eq/kWh, which accounts for 35.40% of the total GHG emissions. The transportation stage has the least environmental impacts, and is the main contributor to METP, GWP and ADF. The environmental damage in the whole life cycle of three batteries is mainly reflected in the following five aspects: METP, GWP, HTP, ADF and FETP. It is found that hydrometallurgy recycling of LFP batteries can effectively relieve the environmental pressure. NCM622 and NCM811 batteries have obvious environmental benefits on METP, HTP, GWP and ADF, but at the same time increase the environmental impacts of HTP, FETP and METP.

• 2 The environmental impacts of LFP batteries under different power combinations over the next 30 years is studied. It is found that increasing the proportion of clean energy use in production Stage could effectively ease the environmental burden, especially METP and GWP. TETP are the lowest change rates among the 11 indexes, which is mainly related to the way of energy development and utilization. Giving priority to the use of wind power has positive effect on China’s goal of carbon neutrality. Sensitivity analysis shows that the precursor of NCM battery is the key factor to produce environmental impacts. In this study, the sol–gel method is used instead of hydrothermal method to prepare cathode materials, which could effectively improve the environmental impacts.

• 3 Given that China’s electricity mix is still dominated by coal, LFP batteries are more environmentally friendly for BEVs. This study provides a reference for understanding the environmental risks of LIBs for BEVs, and provides a path reference for realizing the goal of carbon neutrality of LIBs in China: (a) Using green electricity and increasing the proportion of clean energy; (b) Optimizing the production process of LIBs, especially the production of cathode materials; (c) Strengthening the technical management of recycling phase, which can effectively reduce resource and energy consumption.

NCM batteries rely on precious metals such as nickel, cobalt and manganese, have achieved high energy density but pose significant environmental risks. On the other hand, LFP batteries are more eco-friendly but still have lower energy density compared to ternary lithium batteries. In future, priority should be given to green electricity and optimizing production processes to alleviate the environmental impacts of LIBs.

Appendix

See Tables 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18.

Table 7 Materials and energy flows for LFP battery cathode material manufacturing per kWh

Table 8 Materials and energy flows for LFP battery anode material manufacturing per kWh

Table 9 Production of the electrolyte for the LFP battery requires both material and energy flows

Table 10 Materials and energy flows for NCM811 battery cathode material manufacturing per kWh

Table 11 Materials and energy flows for NCM811 battery anode material manufacturing per kWh

Table 12 Production of the electrolyte for the NCM811 battery requires both material and energy flows

Table 13 Materials and energy flows for NCM622 battery cathode material manufacturing per kWh

Table 14 Materials and energy flows for NCM622 battery anode material manufacturing per kWh

Table 15 Production of the electrolyte for the NCM622 battery requires both material and energy flows

Table 16 Inventory information on the hydrometallurgy technique of recycling 1 kWh LFP battery

Table 17 Inventory information on the hydrometallurgy technique of recycling 1 kWh NCM811 battery

Table 18 Inventory information on the hydrometallurgy technique of recycling 1 kWh NCM622 battery