Environmental concerns over the burning of fossil fuels have made electric vehicles (EVs) a growing trend in personal transportation in the United States and globally. Yet even with a downturn in US auto sales in 2020 during the COVID pandemic, EV sales in the United States still grew while sales of other vehicles waned.
The most important EV component is its rechargeable lithium-ion battery. Manufacturing equipment used in the processing of lithium for these batteries will, as a result, be needed to meet this exponentially growing demand. Manufacturing equipment is required to mix slurries, make electrodes, and assemble the battery’s cells to build a lithium-ion battery. In fact, only a handful of companies specialize in making industrial equipment for working with lithium and other raw materials that go into these vehicle batteries, with most of these located in Asia.
However, the Inflation Reduction Act passed by the US Congress in August 2022 requires that a certain portion of the processing and extraction of materials take place within the United States or its free-trade partner nations. With this encouragement to develop North American lithium-ion battery manufacturing, equipment makers in the United States will likely keep busy as they seek to keep up with the surging demand for their products.
Lithium-Ion Battery Operation, Production & Recycling
Rechargeable lithium-ion batteries weren’t first used to power vehicles; many are still used for other purposes. They became commercially available as rechargeable batteries for consumers in the early 1990s, after safety issues regarding the instability of lithium were largely resolved through the use of lithium ions rather than the use of the metal itself. Lithium-ion batteries are used for powering mobile phones, laptops, and an assortment of other electrical devices, along with powering EVs.
These electrochemical batteries consist of anodes, cathodes, electrolytes, separators, and dual current collectors, one positive and one negative. The lithium is stored in the anode and cathode. Electrolytes carry lithium ions with a positive charge from the anode to the cathode and back again through the separator. The moving lithium ions create free electrons at the anode, which then charges the positive current collector. This electrical current flows from this positive current collector and through the device being powered to the negative current collector, while the separator blocks the flow of electrons within the battery.
Lithium-Ion Battery Production
Production amounts to about a quarter of the cost of lithium-ion battery manufacturing. Manufacturers use the equipment for each of the three main stages of fabrication: making the electrodes, assembling the cells, and configuring these cells within the battery. Each stage also has sub-processes, from coating the anodes and cathodes to the final packaging of the end product.
Stage One: Making Electrodes
The first stage involves forming a homogeneous slurry by mixing electrode materials with a conductive binder into a solvent. The anode is made from a carbon-based material, while the cathode contains lithium metal oxide. So as not to contaminate these two active materials, anodes and cathodes are typically fabricated in different parts of the plant.
The current collector is coated on both sides by the slurry, in either a constant or recurrent manner, with aluminum foil covering the cathode and copper foil covering the anode. This process entails using implements like anilox rollers, doctor blades, or slot dies, with the electrode coating’s thickness controlled by a coating machine.
Once coated, the foil gets fed directly into a drying oven, where the solvent evaporates. Following this, a calendaring process occurs, compressing the coated foils through a pair of rotating rollers. This adjusts the electrodes’ physical properties.
The finished electrodes are cleaned before being fed into slitting machines following calendaring. The electrodes are then sliced into slim strips before recoiling them. These coils next go into a vacuum oven, where any leftover moisture and solvent are removed.
Equipment used in making electrodes includes:
- Calendaring or roll-pressing equipment
- Coating machinery
- Equipment used in this first stage includes:
- Industrial dryers
- Machines for cutting electrodes
- Mixers for making slurry
- Vacuum drying ovens
Stage 2: Assembling Cells
After preparing the electrodes, they’re brought into a dry room for sub-processing assembly of the cell’s internal structure, which involves layering the separator between the anode and cathode. With this stage of lithium-ion battery manufacturing, equipment is typically automated. The terminals or cell tabs are then connected to the assembled cell structure with safety devices, welding it in place via a laser or ultrasonic process. This subassembly inserts into the cell housing, which is either a pouch or metal casing, depending on the design of the cell. A laser welder or other heating process seals the housing, leaving a gap where the electrolyte can be injected.
Using a high-precision dosing needle, the housed cell is filled with electrolytes before it’s sealed. As moisture will cause the decomposition of the electrolyte with toxic gasses emitted as a result, this process must be carried out in a dry room. Through the application of pressure to the cell, a capillary effect is activated. A batch or serial number is then applied to the case, labeling the finished cell.
Equipment used in assembling cells includes:
- Die cutting machinery
- Electrolyte filling equipment
- Sealing and tab welding machinery
- Stacking equipment
- Winding machine
Stage 3: Configuring Cells
After injecting electrolytes into the battery’s cell, the configuration process tests the cells by charging and then discharging them. These cells make contact with spring-loaded pins in information racks to precisely charge or discharge them. This embeds lithium ions into the graphite crystal structure on the anode, forming a protective layer between the electrode and electrolyte. The protective film will affect how long the battery lasts and its performance.
After this configuration, cell performance and other characteristics are monitored for quality control over up to three weeks. This aging process uses first high, then normal, temperatures, with the cells stored in shelves or cabinets. If no significant change is noted over this period, the cells are considered fully functional.
Once aged, cells are tested at an end-of-line test rig. They’re taken to this testing station to be discharged to determine their capacity measurement. Other tests can also be carried out, including internal resistance measurements, leakage tests, optical inspections, and further pulse tests. Once successfully completed, after these tests, the cells are assembled into battery packs, which are considered ready for end use.
Equipment used in configuring cells includes:
- Aging cabinets
- Battery formation testers
- Battery testing equipment
- Grading machinery
This grading and testing equipment accounts for about 70 percent of the total equipment cost, though this varies depending on how much of the process is automated process.
Lithium-Ion Battery Applications & Development
Because of their energy efficiency, high power-to-weight ratio, performance at high temperatures, and low self-discharge, lithium-ion batteries are used in the majority of portable consumer electronic products. Lithium-ion batteries offer higher energy per unit of mass than any other type of energy storage system. These days, most EVs and hybrids also use lithium-ion batteries for similar reasons, though they vary chemically from their smaller cousins in consumer products. Due to their higher cost, researchers are still working on extending these batteries’ lifecycles and addressing safety concerns regarding overheating.
Lithium-Ion Battery Recycling
Additionally, most components within lithium-ion batteries are recyclable. Even so, the cost of recovery continues to challenge the industry. For this reason, in 2019, the US Department of Energy (DOE) began sponsoring the Lithium-Ion Battery Recycling Prize. Partnering with the National Renewable Energy Laboratory and Advanced Manufacturing Office, the DOE wants to make the recycling of lithium-ion batteries more economically viable.
Lithium-Ion Battery Recycling Prize seeks to do this by:
- Enabling US-based recyclers to achieve economies of scale through the provision of higher volume feedstocks.
- Attracting investment from local and state entities, both private and public, to collect, store and transport used lithium-ion batteries at scale.
- Conceptualizing and developing solutions to achieve a 90 percent recovery of materials from discarded lithium-ion batteries.
- Bringing together technologies with innovators and businesses to create practical and comprehensive solutions to challenges currently faced by the supply chain for lithium-ion battery recycling.
Because the EV industry is less than two decades old in the United States, very few of these batteries have reached the end of their lifecycles. This will change as more EVs rapidly enter the auto market, offering an ever-increasing supply of batteries to be recycled. The benefits of recycling lithium-ion batteries are twofold: it keeps hazardous materials out of the waste stream and reintroduces these critical materials for battery production back into the supply chain. While the material will be reprocessed similarly to raw materials once removed from the batteries, a few recycling methods are utilized to separate the materials.
These fall into the following general categories:
- Smelting processes recover base elements or salts and are currently operational at scale for multiple types of batteries, including lithium-ion and nickel-metal hybrids. Smelting burns off the organic material, which includes the carbon anodes and electrolytes. Valuable metals recovered from the process are then sent to be refined for reuse. Other materials like lithium remain in the slag, often used as a concrete additive.
- Direct recovery involves separating components in a series of physical and chemical processes, where all material can be recovered. This process uses lower temperatures and minimal energy.
- Intermediate recovery processes that accept multiple battery types yet recover materials more efficiently than smelting look to be the best bet until the number of lithium-ion batteries discarded grows to a point where they can be recycled alone at scale.
The main stumbling block with recycling the materials used in lithium-ion batteries involves efficiently recovering high-value materials like lithium. EV battery design thus must consider disassembly and recycling to make their production sustainable. Recycling them will become simpler and more economically viable through the standardization of design, materials, and batteries.
Elements Within Lithium-Ion Batteries
An important part of recycling involves knowing what elements are recoverable in a lithium-ion battery. Manufacturing equipment that breaks down particles in raw lithium can also be modified to work in material recovery efforts for lithium-ion batteries. Procedures for recovering these materials are being tested and developed.
Some experimental recovery methods on these materials include:
- Lithium cobalt oxide, which has been used in lithium-ion batteries since the 1980s as cathode material, can be dispersed in a water solution containing 0.2 percent sodium hexametaphosphate.
- Lithium manganese oxide can also be dispersed in 0.2 sodium hexametaphosphate, along with an optimal 3-minute exposure to ultrasound.
- Lithium titanate is often used as the anode material for fast-recharging lithium titanate batteries, with the powdered material dispersed within de-ionized water with 0.2 percent sodium hexametaphosphate; though ultrasound was used, it didn’t improve dispersion. A similar experiment with lithium titanate used a de-ionized water solution with a 0.2 percent phosphoric acid instead of sodium hexametaphosphate.
Particle size distribution (PSD) of the materials used in lithium-ion batteries is important. The size of the particles affects both coulombic efficiency and the capacity of a battery. Reducing the PSD increases the surface area in specific areas, which changes the characteristics of the battery while also altering the size of voids between particles to reduce the battery’s capacity.
Prater Industries: Lithium-Ion Battery Manufacturing Equipment
The need for lithium and other minerals used by the EV industry continues to grow exponentially. Prater Industries makes particle reduction equipment ideal for processing the raw or recycled materials used in lithium-ion battery manufacturing. Equipment like Prater’s fine grinding mills is currently in use by manufacturers for grinding material for lithium-ion batteries’ anodes and cathodes. Our CLM air classifier mill is also used for milling lithium and recovering material from spent batteries.
We also make a wide array of customizable industrial equipment and tailor whole systems for processing or recovering the bulk powdered and solid minerals the EV industry needs. With our many decades of experience designing custom systems for such material applications, Prater looks to supply industrial equipment and systems for humanity’s future. We invite you to contact us today to learn more about how Prater equipment can support lithium-ion battery manufacturing and recycling.