A lithium-ion battery, or Li-ion battery, is a type of rechargeable battery that stores energy by moving lithium ions between materials inside the battery. Compared to other rechargeable batteries, Li-ion batteries usually store more energy, have higher energy density, and last longer. In the 30 years after Li-ion batteries were first sold in 1991, their energy storage per unit volume tripled, while their cost dropped by ten times. By late 2024, the world used more than 1 terawatt-hour of Li-ion battery power each year, and production was more than twice that amount.

The invention and use of Li-ion batteries have greatly influenced technology, as recognized by the 2019 Nobel Prize in Chemistry. These batteries power portable electronics, such as laptops, cell phones, and electric cars. They are also used for large-scale energy storage, in military and aerospace systems, and in many other devices. Li-ion batteries come in many different sizes and shapes, depending on the device or manufacturer. Most have a standard voltage of 3.6 or 3.7 volts.

In the 1970s, M. Stanley Whittingham created the first rechargeable Li-ion battery using a titanium disulfide cathode and a lithium-aluminum anode, but it was not safe and never sold. John Goodenough later improved this design by using lithium cobalt oxide as a cathode in 1980. Akira Yoshino made the first modern Li-ion battery in 1985, using a carbon anode instead of lithium metal. This design was commercialized in 1991 by a team at Sony and Asahi Kasei. Whittingham, Goodenough, and Yoshino were awarded the 2019 Nobel Prize in Chemistry for their work on Li-ion batteries.

Li-ion batteries can be dangerous because they contain flammable materials. Researchers are working to make safer versions, such as solid-state batteries that do not use flammable electrolytes. Recycling Li-ion batteries can create harmful waste from toxic metals and may also pose fire risks. Mining for lithium and other minerals used in batteries can cause environmental problems, such as high water use in dry regions or the use of minerals linked to conflicts, like cobalt. These issues have led scientists to explore more efficient ways to use minerals or find alternatives, such as lithium iron phosphate batteries or non-lithium batteries like sodium-ion or iron-air batteries.

There are at least 12 different types of Li-ion battery chemistries. These batteries can be designed to store more energy or deliver more power. Handheld electronics often use lithium polymer batteries, which have a gel-like electrolyte, a lithium cobalt oxide cathode, and a graphite anode. These materials provide high energy storage. Other chemistries, such as lithium iron phosphate, lithium manganese oxide, and lithium nickel manganese cobalt oxide, may last longer and provide more power. These materials are widely used in electric vehicles, which help reduce greenhouse gas emissions when paired with renewable energy. Another type, lithium nickel cobalt aluminum oxide, is also used in electric vehicle batteries.

History

One of the earliest examples of research into lithium-ion batteries was a CuF₂/Li battery developed by NASA in 1965. The breakthrough that led to the first modern lithium-ion battery was made by British chemist M. Stanley Whittingham in 1974. He used titanium disulfide (TiS₂) as a cathode material, which has a layered structure that can absorb lithium ions without changing its structure much. Exxon tried to commercialize this battery in the late 1970s but found the process expensive and complex. TiS₂ is sensitive to moisture and releases toxic hydrogen sulfide (H₂S) gas when exposed to water. Additionally, the batteries were likely to catch fire on their own because of the presence of metallic lithium in the cells. For these reasons, Exxon stopped developing Whittingham’s battery.

In 1980, scientists Ned A. Godshall and others, as well as Koichi Mizushima and John B. Goodenough, tested other materials and replaced TiS₂ with lithium cobalt oxide (LiCoO₂, or LCO). This material has a similar layered structure but offers a higher voltage and is more stable in air. It was later used in the first commercial lithium-ion battery, though it did not solve the problem of flammability.

Early lithium-ion batteries used lithium metal anodes, but these were eventually abandoned because lithium metal is unstable and can form tiny branches called dendrites, which can cause short circuits. The solution was to use an intercalation anode, similar to the cathode, which prevents lithium metal from forming during charging. Jürgen Otto Besenhard first demonstrated lithium ions reversing into graphite anodes in 1974. However, the solvents he used, such as carbonates, broke down quickly, leading to short battery life. Later, in 1980, Rachid Yazami used a more stable solid organic electrolyte called polyethylene oxide.

In 1985, Akira Yoshino at Asahi Kasei Corporation discovered that petroleum coke, a less graphitized form of carbon, could reversibly absorb lithium ions at a low voltage without damaging its structure. Its stability comes from amorphous carbon regions that hold its layers together. Although petroleum coke has lower capacity than graphite (~Li₀.₅C₆, 186 mAh g⁻¹), it became the first commercial intercalation anode for lithium-ion batteries because of its long-lasting performance. In 1987, Yoshino patented the first commercial lithium-ion battery using this anode. He paired it with LiCoO₂ as the cathode and a carbonate ester-based electrolyte. The battery was assembled in a discharged state, making it safer and cheaper to produce. In 1991, Sony began selling the first rechargeable lithium-ion batteries using Yoshino’s design. The following year, a joint venture between Toshiba and Asahi Kasei Co. also released a lithium-ion battery.

Significant improvements in energy density occurred in the 1990s when Yoshino’s soft carbon anode was replaced first with hard carbon and later with graphite. In 1990, Jeff Dahn and colleagues at Dalhousie University (Canada) reported that lithium ions could reversibly enter graphite in the presence of ethylene carbonate solvent, which is solid at room temperature and mixed with other solvents to form a liquid. This discovery completed the design of the modern lithium-ion battery.

In 2010, global lithium-ion battery production capacity was 20 gigawatt-hours. By 2016, it reached 28 GWh, with 16.4 GWh in China. In 2020, global production capacity was 767 GWh, with China accounting for 75%. Production in 2021 is estimated to be between 200 and 600 GWh, and predictions for 2023 range from 400 to 1,100 GWh.

In 2012, John B. Goodenough, Rachid Yazami, and Akira Yoshino received the IEEE Medal for Environmental and Safety Technologies for developing the lithium-ion battery. In 2019, Goodenough, Whittingham, and Yoshino were awarded the Nobel Prize in Chemistry for their work on lithium-ion batteries. Jeff Dahn received the ECS Battery Division Technology Award (2011) and the Yeager Award from the International Battery Materials Association (2016).

Design

The negative electrode in a typical lithium-ion battery is made of graphite. The positive electrode is usually a metal oxide or phosphate. The electrolyte is lithium salt dissolved in an organic solvent. The negative electrode (anode during discharge) and the positive electrode (cathode during discharge) are separated by a material that prevents them from touching and causing a short. The electrodes are connected to the circuit through metal pieces called current collectors.

During charging, the roles of the negative and positive electrodes switch (anode and cathode). However, in battery design discussions, the negative electrode is often called "the anode" and the positive electrode "the cathode."

In its fully lithiated state (LiC₆), graphite has a theoretical capacity of 1339 coulombs per gram (372 mAh/g). The positive electrode is usually one of three types: a layered oxide (like lithium cobalt oxide), a polyanion (like lithium iron phosphate), or a spinel (like lithium manganese oxide). Experimental materials include graphene-containing electrodes, but these are not yet used in commercial batteries due to high costs.

Lithium reacts strongly with water to produce lithium hydroxide (LiOH) and hydrogen gas. To avoid this, batteries use a non-aqueous electrolyte and are sealed to keep moisture out. The non-aqueous electrolyte is a mix of organic carbonates, such as ethylene carbonate and propylene carbonate, containing lithium ion complexes. Ethylene carbonate helps form a protective layer on the carbon anode, but since it is solid at room temperature, a liquid solvent like propylene carbonate is added.

The electrolyte salt is almost always lithium hexafluorophosphate (LiPF₆), which provides good ionic conductivity and stability. The hexafluorophosphate anion protects the aluminum current collector used for the positive electrode. A titanium tab is welded to the aluminum collector. Other salts, like lithium perchlorate (LiClO₄) and lithium bis(trifluoromethanesulfonyl)imide (LiC₂F₆NO₄S₂), are used in research but not in larger batteries because they are incompatible with aluminum collectors. Copper, with a nickel tab, is used for the negative electrode’s current collector.

Current collector designs vary: foil, mesh, foam, etched surfaces, or coatings to improve electrical performance.

The choice of materials affects a lithium-ion battery’s voltage, energy density, lifespan, and safety. Researchers are exploring new designs using nanotechnology to improve performance, such as nano-scale electrode materials and alternative structures.

The materials in the electrodes are compounds containing lithium atoms. While thousands of materials have been tested, only a few are used in commercial batteries. All commercial lithium-ion batteries use intercalation compounds as active materials. The negative electrode is usually graphite, sometimes mixed with silicon to increase capacity. The electrolyte is lithium hexafluorophosphate dissolved in organic carbonates. The positive electrode may use materials like LiCoO₂, LiFePO₄, or lithium nickel manganese cobalt oxides.

During discharge, the negative electrode (anode) sends electrons to the positive electrode (cathode) through the external circuit. At the anode, lithium ions and electrons are produced. Lithium ions move through the electrolyte, while electrons travel through the circuit to the cathode, where they combine with the cathode material. The electrolyte allows lithium ions to move but does not participate in the reaction. Discharging reduces the cell’s chemical potential, transferring energy to the external circuit.

During charging, electrons flow from the positive electrode to the negative electrode through the external circuit. An external power source provides energy, which is stored as chemical energy in the cell. Lithium ions move from the positive to the negative electrode, where they are absorbed into the electrode material through a process called intercalation.

As lithium ions move between the electrodes, these batteries are sometimes called "rocking-chair batteries" or "swing batteries."

The following equations show the chemical reactions (left to right: discharging; right to left: charging):

Negative electrode (graphite):
Positive electrode (lithium-doped cobalt oxide):
Full reaction:

Overdischarging can cause lithium cobalt oxide to produce lithium oxide through an irreversible reaction:

Overcharging up to 5.2 volts may create cobalt (IV) oxide, as shown by x-ray diffraction:

The energy stored in a lithium-ion battery is calculated by multiplying voltage by charge. Each gram of lithium holds 13,901 coulombs of charge. At 3 volts, this equals 41.7 kJ per gram of lithium, or 11.6 kWh per kilogram. This is slightly more than gasoline’s energy, but lithium-ion batteries are heavier due to additional materials.

The voltages in these reactions are higher than those needed to electrolyze water.

During discharge, lithium ions carry current from the negative to the positive electrode through the non-aqueous electrolyte and separator.

During charging, an external power source applies a higher voltage to the cell, forcing electrons to flow from the positive to the negative electrode. Lithium ions also move from the positive

Battery designs and formats

Lithium-ion batteries can have different levels of structure. Small batteries contain only one battery cell. Larger batteries connect cells in parallel to form a module. These modules are then connected in series and parallel to create a pack. Multiple packs may be connected in series to increase the voltage.

Batteries may include temperature sensors, heating and cooling systems, voltage regulator circuits, voltage taps, and charge-state monitors. These parts help reduce safety risks such as overheating and short circuits.

On a larger scale (0.1–5 mm), most commercial lithium-ion batteries use foil current collectors. Aluminum is used for the cathode because it forms a protective layer in LiPF6 electrolytes. Copper is used for the anode because lithium does not combine with it.

Lithium-ion cells come in different shapes, which can generally be grouped into four types:

• Coin cells have a strong metal casing, often made of stainless steel. They have low energy storage and are used mainly in devices like watches, calculators, and research tools. Coin cells are more commonly used for primary lithium-metal batteries.
• Small cylindrical cells have a solid body without terminals and are used in e-bikes, older laptop batteries, and electric vehicles. They usually follow standard sizes.
• Large cylindrical cells have a solid body with large threaded terminals.
• Flat or pouch cells have a soft, flat shape and are used in cell phones and newer laptops. These are lithium-ion polymer batteries.
• Rigid plastic cells with large threaded terminals are used in electric vehicle traction packs.

Cylindrical cells are made by rolling layers of positive electrode, separator, negative electrode, and separator into a single spool, similar to a "swiss roll" or "jelly roll." This is then placed inside a container. One benefit of cylindrical cells is faster production. A drawback is that they may have uneven temperature distribution when used at high discharge rates.

Pouch cells lack a case, which allows them to have the highest energy storage per weight. However, many applications require containment to prevent expansion at high charge levels and for structural support. Both rigid plastic and pouch-style cells are sometimes called prismatic cells because of their rectangular shapes. Three main battery types are used in modern electric vehicles: cylindrical cells (e.g., Tesla), prismatic pouch cells (e.g., LG), and prismatic can cells (e.g., LG, Samsung, Panasonic, and others).

Lithium-ion flow batteries use cathode or anode materials suspended in water or organic solutions.

As of 2014, the smallest lithium-ion cell was pin-shaped, with a diameter of 3.5 mm and a weight of 0.6 grams, made by Panasonic. Coin cells are available for LiCoO2 batteries and are usually labeled with a "LiR" prefix.

The average voltage of LCO (lithium cobalt oxide) chemistry is 3.6 volts when using a hard carbon cathode and 3.7 volts when using a graphite cathode. The graphite version has a more consistent voltage during use.

Uses

Lithium-ion batteries are used in many different ways, such as in consumer electronics, toys, power tools, and electric vehicles.

Less common uses include providing backup power for telecommunications systems. These batteries are also sometimes considered for storing energy for the power grid, but as of 2020, they were not yet cost-effective when used in large amounts.

Some submarines have lithium-ion batteries installed for their operations.

Performance

Lithium-ion batteries can use different materials for their positive and negative electrodes. These choices affect the battery’s energy density and voltage.

The open-circuit voltage of lithium-ion batteries is higher than that of water-based batteries, such as lead–acid, nickel–metal hydride, and nickel–cadmium batteries. As batteries are used and age, their internal resistance increases. This change depends on the voltage and temperature at which the batteries are stored. Higher internal resistance causes the voltage at the battery’s terminals to drop when the battery is under load, which limits the maximum current it can provide. Over time, increasing resistance may prevent the battery from meeting normal discharge current demands without causing a large voltage drop or overheating.

Batteries with lithium iron phosphate positive electrodes and graphite negative electrodes have a nominal open-circuit voltage of 3.2 V and a typical charging voltage of 3.6 V. Batteries with lithium nickel manganese cobalt (NMC) oxide positive electrodes and graphite negative electrodes have a nominal voltage of 3.7 V and a maximum charging voltage of 4.2 V. Charging is done at a constant voltage while limiting the current (charging with a steady current until the battery reaches 4.2 V, then continuing at a constant voltage until the current nearly stops). Charging usually stops when the current is about 3% of the initial charge current. In the past, lithium-ion batteries took at least two hours to fully charge. Modern batteries can now be fully charged in 45 minutes or less. In 2015, researchers showed a small battery with a 600 mAh capacity could reach 68% of its full charge in two minutes, and a 3,000 mAh battery could reach 48% in five minutes. The latter battery had an energy density of 620 W·h/L. This battery used heteroatoms bonded to graphite molecules in the anode.

Battery performance has improved over time. From 1991 to 2005, the energy capacity per dollar of lithium-ion batteries increased more than ten times, from 0.3 W·h per dollar to over 3 W·h per dollar. From 2011 to 2017, improvements averaged 7.5% each year. Between 1991 and 2018, the cost of lithium-ion batteries dropped about 97%, while their energy density more than tripled. Improvements in energy density helped lower costs. Energy density can also increase through chemical changes, such as replacing graphite with silicon in the anode. Silicon anodes improved with graphene nanotubes helped achieve record battery energy densities of up to 350 Wh/kg and lower electric vehicle prices to compete with gasoline-powered vehicles.

Batteries of the same size and shape but with different chemistries may have different energy densities. Jelly roll cells usually have higher energy density than coin or prismatic cells of the same Ah capacity because their layers are packed more tightly. Among cylindrical cells, larger cells generally have higher energy density, though this depends on the thickness of the electrode layers. A disadvantage of large cells is reduced heat transfer from the cell to its surroundings.

An experimental evaluation in 2021 tested a "high-energy" type 3.0 Ah 18650 NMC cell. The test measured round-trip efficiency, which compares the energy stored in the battery during charging to the energy released during discharging. Round-trip efficiency is the percentage of energy that can be used compared to the energy used to charge the battery.

A different experiment in 2017 reported a round-trip efficiency of 85.5% at a 2C charge rate and 97.6% at a 0.1C charge rate.

Lifespan

The lifespan of a lithium-ion battery is usually measured by how many full charge and discharge cycles it can complete before it no longer works well. This is often called "cycle life," and it is defined as the number of cycles needed for the battery to lose 20% of its original capacity. Storing lithium-ion batteries in a fully charged state can also reduce their ability to hold charge and increase resistance, mainly because a layer called the solid electrolyte interface (SEI) keeps growing on the anode. "Calendar life" refers to the total time a battery lasts, including both use and storage. Battery cycle life depends on factors like temperature, how fast it is charged or discharged, and how full it is charged. In real-life uses, such as smartphones or electric cars, batteries are rarely fully charged or discharged, so using full cycles to define lifespan can be confusing. To help clarify, scientists sometimes use "cumulative discharge," which is the total amount of charge (measured in ampere-hours, or Ah) a battery provides over its lifetime. This method adds up partial cycles as fractions of a full cycle. Battery degradation during storage is influenced by temperature and how full the battery is. Storing a battery at 100% charge and high temperatures (over 50 degrees Celsius) can cause a sudden drop in capacity and gas production. Multiplying cumulative discharge by the battery's rated voltage gives the total energy it provides over its life. This helps calculate the cost of energy (including charging costs) per kilowatt-hour.

As a battery ages, it gradually loses its ability to hold charge (called Ah capacity) and its internal resistance increases (which lowers the voltage it can produce during use).

Lithium-ion batteries degrade through several processes, some during use, some during storage, and some all the time. Degradation is strongly affected by temperature: it is minimal at room temperature but increases in very hot (over 35 degrees Celsius) or very cold (below 5 degrees Celsius) environments. Keeping a battery at room temperature helps it last longer. High charge levels also speed up capacity loss. Charging a battery above 90% or discharging it below 10% often causes faster loss of capacity. Keeping a lithium-ion battery between 60% and 80% charge can help reduce this loss.

In a study, scientists used 3D imaging and models to identify the main causes of battery degradation during use. They found that cracks in battery particles and loss of contact between particles and the carbon binder are linked to battery failure. They also discovered that uneven electron movement in thick cathodes is a major cause of degradation during repeated use.

Common ways lithium-ion batteries degrade include:

• SEI growth: The organic liquid inside the battery breaks down at the anode, creating a layer called the SEI. This layer traps lithium ions, reducing the battery's usable charge. The SEI layer thickens over time, increasing resistance and reducing capacity. This process happens more quickly at high temperatures or if the battery is damaged.

• Lithium plating: Lithium can form metal deposits on the anode during fast charging or at low temperatures. This reduces usable charge and increases the risk of internal short circuits or fires. This issue becomes worse with fast charging or cold conditions.

• Loss of active materials: The materials in the battery's electrodes can break down, detach, or change shape during repeated use. This reduces both the charge and power the battery can provide.

• Cathode structure changes: In some batteries, the arrangement of ions in the cathode becomes unstable, leading to lower capacity and voltage.

• Other material breakdowns: The copper current collector in the negative electrode can corrode at low voltages, and the PVDF binder can break down, causing electrode materials to detach and lose usable charge.

These processes are shown in figures, where changes in degradation patterns appear as a "knee" (a sudden change in slope) on graphs of battery capacity versus cycle number.

Most studies on battery aging test at high temperatures (50–60 degrees Celsius) to speed up experiments. Under these conditions, fully charged nickel-cobalt-aluminum and lithium-iron phosphate batteries lose about 20% of their usable charge in 1–2 years. Anode aging is often the main cause of this loss. Manganese-based cathodes degrade faster (by 20–50%) under these conditions, likely because manganese ions dissolve. At room temperature (25 degrees Celsius), degradation happens at about half the speed of high-temperature testing. This suggests lithium-ion batteries might lose about 20% of their usable charge in 3–5 years or 1,000–2,000 cycles. Batteries with titanate anodes avoid SEI growth and can last over 5,000 cycles, but other issues like manganese dissolution or binder breakdown still reduce their lifespan in full cells.

More details about these processes include:

The SEI layer on the anode is made of materials like lithium oxide, lithium fluoride, and carbonates. At high temperatures, these materials can form thick, hard layers that increase resistance and reduce capacity. Gases from chemical breakdown can also raise internal pressure, which is a safety risk. Below 25 degrees Celsius, lithium metal can deposit on the anode, reducing usable charge. Storing batteries at high voltages (over 4.2 volts) can also cause lithium plating.

Electrolyte breakdown includes reactions like hydrolysis and thermal decomposition. Even small amounts of water (as little as 10 parts per million) can cause harmful chemical changes. The compound LiPF6 in the electrolyte can react with LiF and PF5, but this reaction is rare under normal conditions.

Safety

Lithium-ion battery safety was a known issue even before these batteries were first sold in 1991. Fires and explosions often happen because of problems on the negative electrode (anode when discharging, cathode when charging). During normal charging, lithium ions fit into graphite. However, if charging is too fast or the temperature is too low, lithium metal can form on the negative electrode. These metal growths, called dendrites, may pierce the battery’s separator, causing a short circuit, high current, heat, and fire. In other cases, a reaction between the negative electrode material (LiC6) and the solvent (liquid organic carbonate) can happen even when the battery is not in use, if the electrode temperature rises above 70 °C.

Larger lithium-ion batteries, like those in the 18650 format, include safety features such as a current interrupt device (CID) and a positive temperature coefficient (PTC) device. The CID has two metal disks connected by electricity. If internal pressure rises, the disks separate, cutting off the current. The PTC device uses a conductive polymer that heats up and increases resistance when current is too high, reducing the flow.

Lithium-ion batteries can be dangerous because they contain flammable electrolytes and may become pressurized if damaged. Charging too quickly can cause a short circuit, leading to overheating, explosions, or fires. A Li-ion battery fire can start due to:

• Thermal abuse, such as poor cooling or external fire,
• Electrical abuse, such as overcharging or an external short circuit,
• Mechanical abuse, such as penetration or crashes, or
• Internal short circuits caused by manufacturing flaws or aging.

Because of these risks, testing for lithium-ion batteries is stricter than for acid-electrolyte batteries. Tests cover more conditions and include battery-specific checks. Shipping rules also limit how these batteries are transported. Some companies have recalled batteries due to safety issues, such as the 2016 Samsung Galaxy Note 7 recall for battery fires.

Lithium-ion batteries use a flammable liquid electrolyte. A faulty battery can cause a serious fire. Faulty chargers may harm the battery’s protection circuit. Charging at temperatures below 0 °C can cause pure lithium to form on the negative electrode, risking the whole battery pack.

Short-circuiting a battery causes overheating and may lead to fire. Smoke from a thermal runaway in a Li-ion battery is both flammable and harmful. Batteries are tested using the UL 9540A fire standard, and the TS-800 standard checks how fire spreads from one battery container to others.

Around 2010, large lithium-ion batteries were used in aircraft systems. By January 2014, there had been at least four serious battery fires or smoke incidents on Boeing 787 planes, which did not crash but could have. UPS Airlines Flight 6 crashed in Dubai after its cargo of batteries caught fire on their own.

To reduce fire risks, research focuses on developing non-flammable electrolytes. If a lithium-ion battery is damaged, crushed, or overloaded without overcharge protection, problems may occur. An external short circuit can cause an explosion. This can happen if batteries are not disposed of properly but instead thrown with regular waste. Recycling processes may also damage batteries, leading to fires. Twelve such fires were reported in Swiss recycling facilities in 2023.

If overheated or overcharged, Li-ion batteries may experience thermal runaway, where internal reactions raise temperatures above 500 °C. This can ignite other materials, cause leaks, or lead to explosions. Many lithium-ion cells have safety circuits that disconnect the battery if voltage is too high or too low. Poorly designed battery management systems can also cause issues, making it hard to ensure safety.

Lithium-ion cells can be damaged by voltages outside safe ranges (2.5 to 3.65/4.1/4.2 or 4.35 V). Exceeding these ranges causes aging and safety risks. Over time, the small current from protection circuits may drain the battery below its safe level, making it unusable for normal chargers. Many lithium-ion cells cannot be charged safely below 0 °C, as this causes lithium to form on the anode, risking short circuits.

Each lithium-ion cell must include safety features:
– A shut-down separator (to stop overheating),
– A tear-away tab (to release pressure),
– A vent (to relieve pressure from gas),
– A thermal interrupt (to stop overcurrent or overcharging).

These features are needed because the negative electrode produces heat, and the positive electrode may release oxygen. However, these features take up space, add failure points, and may permanently disable the cell. They also increase costs compared to nickel metal hydride batteries, which only need a hydrogen/oxygen recombination device and a backup valve. Contaminants inside the cell can disable safety features. Some cells, like prismatic high-current cells, cannot use vents or thermal interrupts and must rely on internal thermal fuses instead.

Replacing lithium cobalt oxide with lithium iron phosphate (LFP) in batteries improves safety, lifespan, and cycle counts but reduces capacity. As of 2006, LFP batteries were used in electric cars and large systems where safety was critical. In 2016, an LFP-based energy storage system was installed at Paiyun Lodge on Mt. Jade (Yushan) in Taiwan. As of June 2024, the system remained safe.

In 2006, about 10 million Sony laptop batteries were recalled due to metal particles that caused short circuits. These batteries were used in laptops from Dell, Sony, Apple, Lenovo, Panasonic, Toshiba, Hitachi, Fujitsu, and Sharp.

IATA estimates that over a billion lithium metal and lithium-ion cells are transported by air each year. Some types of lithium batteries are restricted due to safety concerns.

Supply chain

The electric vehicle supply chain includes mining and refining raw materials and manufacturing parts like batteries for electric vehicles.

In 2024, 60% of Li-ion battery production came from China.

In the 1990s, the United States was the world's largest miner of lithium, producing one-third of the world's lithium. By 2010, Chile became the leading miner because of lithium brines in Salar de Atacama. By 2024, Chile, Australia, and China were the top three lithium miners.

Extracting lithium, nickel, and cobalt, making solvents, and handling mining byproducts can cause serious environmental and health problems. Lithium extraction can harm aquatic life due to water pollution. It can also cause surface and drinking water contamination, respiratory issues, ecosystem damage, and landscape harm. In arid areas, it uses about 1.9 million liters of water per ton of lithium. Lithium extraction also creates large amounts of waste, such as magnesium and lime.

Lithium mining occurs in North and South America, Asia, South Africa, Australia, and China.

Cobalt for Li-ion batteries is mostly mined in the Democratic Republic of the Congo. Open-pit cobalt mining has caused deforestation and habitat loss in this region.

Open-pit nickel mining has led to environmental damage and pollution in countries like the Philippines and Indonesia. In 2024, nickel mining and processing were major causes of deforestation in Indonesia.

Making one kilogram of Li-ion battery requires about 67 megajoules (MJ) of energy. The carbon footprint of battery manufacturing depends on the energy sources used. A 2019 study estimated that producing one kilowatt-hour of battery power creates about 73 kilograms of CO2 equivalent. Recycling can reduce this carbon footprint significantly.

Recycling lithium-ion batteries is a growing but not fully developed industry. In 2024, only 5% of used electric vehicle batteries were recycled worldwide. Materials like iron, copper, nickel, and cobalt can be recycled, but mining new materials is often cheaper and easier than collecting and processing used batteries. Since 2018, recycling methods have improved, allowing lithium, manganese, aluminum, and graphite to be recovered at industrial scales.

Battery waste creates technical challenges and health risks. Since the environmental impact of electric cars depends heavily on battery production, finding efficient ways to reuse or recycle waste is important. Recycling involves storing batteries before disposal, testing them, disassembling them, and separating components chemically. Reusing batteries is preferred over full recycling because it uses less energy. However, used batteries are more reactive than traditional waste, like tire rubber, and can be dangerous if stored improperly.

The pyrometallurgical method uses high heat to melt parts of the battery into metal alloys like cobalt, copper, iron, and nickel. This is the most common and established recycling method. It can be combined with similar batteries to improve efficiency. The process produces metal alloys, slag, and gas. At high temperatures, polymers in the battery burn off, and the metal alloy can be separated into individual components using hydrometallurgical methods. Slag can be refined or used in cement production. This method is relatively safe, and the heat from burning polymers reduces energy needs. However, plastics, electrolytes, and lithium salts are lost during the process.

The hydrometallurgical method uses water-based solutions, like sulfuric acid, to extract metals from the battery cathode. Factors affecting the process include acid concentration, time, temperature, and the ratio of solid to liquid. Hydrogen peroxide (H2O2) can speed up the process. After leaching, metals like cobalt can be recovered by adjusting the solution's pH. Recent methods aim to directly recreate cathodes from leached metals by matching their composition to target cathodes.

This method requires large amounts of solvent and is costly to neutralize waste. Separating cathodes and anodes before processing is needed, but battery designs make this complex. Shredding and dissolving steps may occur in different locations, adding to the challenge.

Direct recycling involves removing the cathode or anode from the battery, reconditioning it, and reusing it in a new battery. Mixed metal oxides can be added to the new electrode with minimal changes. Lithium is often added to replace losses from battery use. Cathode strips are soaked in NMP and treated with heat and chemicals before being used again.

This method is cost-effective for noncobalt-based batteries because raw materials are not the main cost. It skips expensive purification steps, making it ideal for cheaper cathodes like LiMn2O4 and LiFePO4. Most costs and environmental impact come from manufacturing, not raw materials. Experiments show that direct recycling can restore battery properties similar to new ones.

A drawback is that the condition of the used battery matters. If the battery is still in good condition, direct recycling is cost-effective. However, if the battery is worn out, the cost may not be worth it. The process must be tailored to specific battery types, and rapid battery design changes may make direct recycling less useful over time.

Physical separation methods use mechanical crushing and rely on physical properties like size, density, and magnetism to recover materials. Copper, aluminum, and steel casings can be sorted out. The remaining material, called "black mass," contains nickel, cobalt, lithium, and manganese and requires further processing.

Research

Researchers are working to improve the energy storage, safety, lifespan, recharge speed, cost, and other features of batteries. They are also studying new ways to use and develop these batteries. Solid-state batteries are being studied as a major step forward in battery technology. Scientists believe solid-state batteries could be the best next step in battery development, and many companies are trying to make them widely available.

Studies on lithium-ion batteries focus on making them last longer, store more energy, be safer, cost less, and charge faster. Scientists are exploring non-flammable electrolytes to improve safety, since the organic solvents used in regular electrolytes can catch fire easily. Methods being tested include water-based lithium-ion batteries, ceramic materials, polymer electrolytes, ionic liquids, and systems with high levels of fluorine.

One way to improve batteries is by combining different cathode materials. This helps scientists use the best qualities of each material while reducing their drawbacks. For example, lithium nickel manganese oxide can be coated with lithium iron phosphate using a special mixing method. This creates a material that works better and holds its charge longer. Similar methods have been used with iron (III) phosphate. Scientists now know that not only transition metals but also oxygen in the cathode play a role in battery reactions. This has led to new designs for cathode materials that include oxygen-based reactions, which can increase battery capacity beyond what is possible with metals alone. Computer models help scientists create better materials while reducing damage to their structure. Improvements in understanding oxygen-based reactions have also led to methods like adding fluorine to surfaces, which helps batteries last longer and be safer.