Life Cycle Analysis For Lithium-ion Battery Production And Processing

Rechargeable battery

Discuss about the Life Cycle Analysis for Lithium-ion Battery Production and Processing.

The debate on the impact of automotive emissions on environment has been escalating over the past decades. The Olofsson (1) estimates that transportation sector emits 16% of CO₂, which needs drastic reduction. Different legislative stipulations have been passed to facilitate the reduction of the emissions: for example, Euro-6 and Euro-VI emission stipulations for light and heavy vehicles respectively were introduced in 2014 to regulate the emission of NO_x among the new models (1). With increasing fear on debilitation of fossil fuel and pressing issues of energy security, there is a growing interest on the need to improve energy efficiency. Based on the recent developments from auto industry and the government, Gaines et al (2) observe that batteries are considered to be the most suitable in manufacturing as well as marketing electric-drive cars; both “plug-in hybrid electric vehicles (PHEVs)”  and battery electric vehicles (p.3).

According to Gaines et al (2), effective installation of “viable battery systems for electric-driven vehicles” has the efficacy to minimize fossil fuels consumption as well as reducing greenhouse emissions (GHG) (p.3). Nevertheless, so much is yet to be established insofar as electric-drive performance and impacts of batteries on their efficiencies is concerned. Batteries that contain high specific energy and peculiar life cycle remain the fundamental elements that will facilitate successful manufacture of electric-drive vehicles, however. More importantly, scientists consider lithium-ion batteries (Li-ion) to be the main factor that will enhance the penetration of the technology. Nelson et al (3) attest that the nature of electric-drive market is multi-faceted— in terms of engineering execution, consumer preference, and affordability (2).

 Essentially, the impact of such vehicles on the environmental performance is among the key driving factors towards their developments. On the crux of the matter is emission and energy efficiency of battery cells. However, there are some existential trade-offs that are inevitable when deployment of electric-drive vehicle will be effected. The energy trade-off necessitates quantification in developing conventional cars by lightweight materials, which reflects the balance between extra energy incurred in developing lightweight material and the fuel saved in driving it, due to the reduced weight (3).

Like any other product system, the burdens of life-cycle batteries emanates from different life-cycle phases, for example, during production of the material, during production and the usage of the battery, or during battery recycling phase. Adequate information on challenges incurred when developing lithium component materials like iron phosphate, lithium cobalt dioxide, lithium hexafuolorophosphate, and lithium nickel dioxide — including some process information— is still lacking. Due to this absence, estimation of the production energy as well as emissions with regard to the life cycle has been made difficult. This paper provides an overview on the impacts of lithium-ion life cycle batteries. The paper focuses on the burden of battery recycling to the production of active materials, which have not been properly characterized hitherto.

• Goal

Production of active materials: Lithium Carbonate

The objective of this paper is to examine the life cycle impacts of Lithium-ion batteries. Special interest is placed on the burden of the production process and recycling process of Li-ion battery cells. Due to the scarcity of materials used in the manufacturing of Li-ion, the paper dissects recycling processes that have the efficacy to underscore energy efficiency and reduce emissions.

• Life Cycle Assessment

Generally, LCA method is used to dissect the environmental consequences of an entire life cycle that involves production of a given product or service (1). The most common areas, according to Olofsson (1) where the knowledge of LCA is applied include “product development, production processes, and waste management” (p.2). The method has become increasingly significant for environmental communication. On product development, LCA is facilitates assessment of potential hotspots of a product life cycle and improves development of eco-design, which provides a springboard to identify “the most optimal design” at the conceptual phase (1). In order to realize the optimal design it is imperative to avoid hazardous materials, cut down the energy used in production stage, use light materials and high quality features to encourage weight minimization, and use materials that can be upgraded, repaired, recycled, and reused.

• Functional Unit

The use of batteries to develop small-scale electric sources and portable devices has been on upward trajectory. Depending on their capacities, batteries can be used to power a variety of electronic devices and automotive. Young (4) observes that the capability of rechargeable battery to store chemical energy and produce electric energy, as well their durability feature has made it more prevalent in today’s society. Olofsson (1) asserts that when battery cell is connected to an external circuit, “oxidation and reduction reactions occur at the negative and positive electrodes respectively” (p.4). Consequently, the electrons flow towards and the external circuit while the ions flow within electrodes via electrolyte. An electric insulator separates the anode and the cathode, and facilitates the flow of electrons to the external circuit only. The insulator also slows down the reaction process when the cell is connected to an external source. The pendulum of the amount of energy that the battery has swings from state of charge (SOC) to discharge, depending on how the battery is used (4).

• Materials available in Lithium-ion batteries/ components

Li et al (5) state that LCA is the most appropriate method when it comes to comparing alternative technological systems, since it entails broad assessment of life cycle of a product or a service, including production of materials, service provision, and maintenance. The paper focuses on quantitative elements of LCA. The paper relies on Gaines et al analysis of GREETZ 2.7 model to examine impact of Lithium-ion batteries. Dunn et al (6) hold that Li-ion batteries have been considered efficient in contemporary as well as future battery technology because they quintessentially have high volumes of energy and gravimetric power. The interplay flow of lithium ions between anode and cathode forms the central basis of Li-ion batteries mechanism. The electrodes are made up of conducting foil. Between the electrodes lies electrolyte. The active component of electrode is made of intercalation materials that have the efficacy to host Li-ions without dismantling their structures. Most chemistries prefer using graphite to make cathode material (4).

Generally, Lithium is extracted from spodumene or brine-lake deposits (2). Due to energy consumption and economic purposes, brine-lake resources are considered to be more efficient and have the capacity to meet the surging demand of for Li-ion automotive batteries. During the extraction process, extensive pumping of brine from brine well “into a solar evaporation pond” occurs and the brine is left to concentrate (2). Once sufficient evaporation and concentration has occurred, pumping of brines to successive ponds follows until crystallization and precipitation of sodium chloride and other salts takes place (4). After pumping the brine into 4-5 ponds, addition of slake lime— to precipitate calcium and magnesium salts— follow. This results to the production of magnesia and gypsum. When more slake-lime is added to the successive ponds, depletion of calcium, magnesium, and sodium salts occurs until brine with capacity of 0.5% lithium can be redirected to a manufacturing plant that extracts lithium from lithium carbonate.

• Spodumene

Another source of lithium is spodumene. Based on Gaines et al analysis (2), spodumene is a mineral that consist of “lithium aluminium inosilicate— LiAl(SiO3)” (p.6). Due to efficiency concerns, its production from minerals has drastically reduced. Eventually, new cost-effective technique, which involves “production from salars,” has been discovered (1). Nevertheless, producers still consider extraction from mineral deposits, in pursuit of achieving supply diversification and reducing reliability of the external suppliers (4). Besides extracting and processing the ore and raw spodumene must be subjected to a temperature of 1000^oC in order to effectively transform alpha to beta and facilitate percolation “using sulphuric acid” (2). The next process involves recovering of lithium in form of lithium salts.

The materials that are used in making cathode are manufactured through oxidation of lithium carbonate at a very high temperature. Another chemical used in the process is Lithium hydroxide, which requires special handling during mixing process. Reactions in solid state at a range of temperatures between 600 to 800^oC are a fundamental requirement to ensure there is maximum crystallization and that suitable structures are obtained (3). Iriyama et al (7) assert that fossil energy is the most suitable for this process. Structural as well as physical features like packing density and morphology are the key determinants in establishing the appropriateness of the material that should be used in cathode for Lithium-ion cells (1).

The most commonly used materials in anode production are soft carbon, hard carbon, graphite, and mesocarbon micro-bead (6). Essentially, a temperature of 2700^oC is needed for graphitization of synthetic graphite materials (2). The process involves huge consumption of energy, particularly fossil fuels. In the recent past, there has been usage of amorphous carbon layer as a robust way of protecting carbonaceous anode cells against corrosion during cell working periods. According to Casas et al (8) process also involves usage of gas-phase substances like methane and propylene, which need to be exposed to a temperature of 700^oC to crack them (1).

Other materials that have been widely used to supplant graphite anodes in the recent past are components of “Lithium titanate (Li₄Ti₅O₁₂).” Li₄Ti₅O₁₂ is preferred due to its high-energy supply. To produce Li₄Ti₅O_1, a reaction of Titania—TiO₂ and Li₂CO₃ is conducted in crystalline structure, at a temperature of 859^oC, in the air (1). The process is less energy-intensive compared to the graphite production. Another advantage of Li₄Ti₅O₁ is that it does not react with the electrolyte. Li₄Ti₅O₁ anode also allows faster charge/discharge, insofar as the diffusion lengths are not long. However, for Li₄Ti₅O₁ anode to be effective, according to Oloffson (1), they have to be used with “high potential cathodes” to minimize the “open circuit voltage (OCV)” (p.22). The weight of the material may also be disadvantageous in locomotive purposes.

• Inventory analysis

The first step of manufacturing Li-ion battery involves processing cathode paste, which is obtained from purchased LiCoO₂ powder and binder powder, among other additives, followed by intense pumping to the coating machine (2). During the second stage, coating machines facilitate the spreading of the paste into a thickness of 200-250 μm on each side of the aluminium foil. 25-40% of the thickness is lost during drying process (2). To achieve a uniform thickness, coated sheet has to be compressed.

In the third stage, production of graphite paste takes place, and then distributed on copper foil to develop anodes. Another important activity in this stage is the trimming off the foil edges. Splicing in of the new foil may also result to loss of some quantity of the material since taped area have to be scraped, which can be redirected to recycling machines (4). The fourth stage involves wounding up of the anode, cathode, and the insulator layers, and then fixing them into rectangular or cylindrical casing. Happening at the fifth stage is the filling of the cells with electrolyte and purchased paste from a chemical supplier (1).

During the sixth stage, attachment of safety devices, seals, insulters, and valves, followed by plication of the cells is done. At the seventh stage, fabrication of fully discharged cells is conducted by charging them with a cycler. Cyclers have the capacity to supply high current for electric car batteries. The stage also involves conditioning and testing—charging and discharging them repeatedly to authenticate product quality (6). Energy is involved at this stage and caution is paramount at this stage to outbreak of fires due to large capacity of the batteries that are tested. The main purpose of the eighth stage is to fit the cells with electronic circuit gadgets to control the process of charging and discharging (2). At the final stage, non-homogenous electrode devices, defective cells, and other left overs are dumped to the scrap. Scrap materials may be recycled.

Recycling of batteries has become more dynamic due to diversification of feedstock, which includes several types of batteries, some of which are inimical to human health in particular and the environment in general. According to Gaines (2), “recycling electronic consumer batteries” keeps the companies operational until car batteries are disposed for recycling in huge volumes (p.9). The disposal of automotive batteries makes the recycling process efficient and improves standardization exercise. Income obtained from cobalt recovery stimulates the recycling process (3). However, due to decline in the use of cobalt, other initiatives to make the recycling process lucrative business must be identified.

Through the recycling process, several materials can be recovered at different stages of production. For instance, smelting process has the efficacy to retrieve the basic elements and salts. Smelting process occurs at very high temperatures and involves burning of carbon anodes and electrolytes as reductant (2). Cobalt and nickel, which are the valuable metals recovered from the process, are redirected to the refining plant to make them more conducive for any purpose. Other elements that are contained in the slag like lithium are used for additive function. Hydrometallurgical process is the main method that is used to recover lithium from the slag (2). The process of recovering battery grade materials demands a high uniform feed since contamination of the feed with impurities may be detrimental to the product quality. Therefore, component must be separated through effective variety of chemical and physical technique to ensure that all active elements are recovered. Other active materials may need to be purification to make them appropriate for reuse in new battery cells. However, the separator cannot be reused since its material cannot be recycled. While many papers have discussed recycling of Lithium-ion batteries, only a few companies, 3 to be exact, have detailed germane information that could be used in current analysis. These processes are analysed below:

Umicore is a European battery processing company. It gathers used batteries and dispose them to its processing plant, which is designated in Sweden. Once the materials are collected, they are smelted. The next step is combustion of organic materials in the batteries like carbon electrodes, plastics, and electrolyte solvents. The combustion steers the smelter and carbon is used a reductant for some metals. Recovered elements, nickel and cobalt, are shipped to a refinery plant in Belgium, where CoCl₂ is manufactured. After processing CoCl_2, it is transported to South Korea to manufacture LiCoO₂ for battery cells. Recovery of nickel and cobalt helps makes the process efficient, considering that at least 70% of the energy required for their extraction from the sulphide ores is saved. The production process also prevents emission of Sulphur oxide gase. However, the aluminium and lithium elements from the smelting process flows into the slag, which has low value uses. The subjection of waste gases to extremely high temperatures ensures that they are not released into the environment. According to the company, out of 93% recovered lithium-ion batteries, 69% is metal, 10% is carbon, and 14% is plastic (2).

This method has been commonly used in battery processing since 1993 in Canada to manufacture Lithium-ion batteries for different purposes (3). In 2009, Toxco Company was granted a licence by the US Department of Energy to reprocess Lithium-ion battery cells at plant designated at Ohio (2). Through mechanical and chemical recycling process, products obtained from the process are “copper cobalt, fluff, and cobalt filter cake” (2). Copper cobalt is used to extract metals like copper, cobalt, nickel, and aluminium. On the other hand, cobalt filter cake is reused to coat appliances. Sodium Chloride was added to the resultant solution in order to precipitate Li₂Co_3. The mechanical and chemical recycling process ensures that the emission is minimized. One benefit of this process is that it is not energy-intensive. Besides, it is possible to recycle at least 60% of the battery pack materials and 10 percent reused. The fluff consists of 25% of the battery pack: it is first landfilled, and then the plastic can be retrieved when their capacity is high enough to ensure there is efficiency (2).

Orengon Company is the developer of this process. The company has partnered with RSR, a recycling company in Texas. Eco-Bat process consumes less energy hence it more efficient. The process involves reusing of electrolyte solvent and salts. Like other recycling processes, reusing the separator is impossible. The metal elements are retrieved and used for recycling. Battery pack casing may also be reused, but the process will depend on the system of configuration in place. The process is a quintessentially possibility of design-for-recycling method. Extraction of electrolyte if facilitated by using supercritical CO₂, which carries away the salt and can be reused. The CO₂ used in this process can be obtained from burning waste. The leftovers from the structure can be broken down into small fragments to enhance the separation process. This process ensures that active elements are recovered and the new battery is manufactured with minimal treatment. About 80% of the materials used in the process can be recycle. However, the method requires additional separation process to process a mixed feed and to produce high quality final products.

This section provides a brief evaluation of inventory development based on cradle-to-gate (CTG) life cycle performance of Lithium-ion battery. This involves investigation of alternative fuels as well as advanced automotive technology. Total energy cycle analysis remains the germane approach in this process, which includes plug and the vehicle cycle. The complete energy phases include (a) energy cycle, which is composed of categories, pump-to-wheel (PTW) and wheel-to-pump stages, (b) automotive cycle, which involves battery production. Gaines (2) uses GREET “1.8d.0 and GREET 2.7” to assess the total energy cycle of PHEV20 to establish that there is significant difference between life cycle energy use and the vehicle cycle. At  PHEV20, WTP accounts for 23% while PTW accounts for 61%. This reflects the entire environmental score. Large amount of life cycle energy used during battery processing cannot be retrieved during recycling. Nevertheless, materials like copper, aluminium, nickel, and still were able to be recycled.

Moot discussion on environmental impact is corollary to any type of technological development that involves switching from fossil energy. The main challenge with using lithium-ion battery cells is that there is scarcity of lithium. Lithium-ion battery cells are the only material that can be used in manufacturing electric vehicles, with no substitute. The main contentious issue is what will happen in the event that there is scarcity of lithium. There is still no satisfying evidence that the rate at which lithium is processed will be consistent with rate at which electric vehicles will be manufactured. The geographical location is another factor. Currently, lithium deposits are only concentrated in Bolivia and Chile, though other countries like China, Belgium, and Canada have reserves in lower capacity. Manganese, cobalt, and nickel, which are possible elements in the cathode foils, are also scarce. Expansion of electric vehicles may easily lead to their depletion. On the other hand, copper is very expensive and may not be cost-effective.

The research on how to extract sufficient lithium ores should be intensified. Since there is no actual data that could be used to determine the actual thickness that may result to crash, an investigation should be carried out to fill the gap. The life cycle lengths and their impacts to the environment should further be investigated to establish the best techniques of recycling lithium and reducing emission. Besides, the  durability of batteries should be validated with effective experiments, which are faster and efficient. Since cooling process is vital stage in battery pack, the choice of cooling system should be made with a lot of care to reduce the volume of impurities during the process.

Conclusion

Based on the results obtained from the assessment of life cycle of Li-ion, it is evident that recycling of materials used to recycle lithium significantly reduces the amount of energy used in the production of the material. This is a significant step towards achieving energy efficiency and reducing emissions. However, there is still lack of credible process that can effectively result to voluminous extraction and processing of lithium ions.

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