A lithium-ion battery (sometimes Li-ion battery or LIB) is a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge, and back when charging. Chemistry, performance, cost, and safety characteristics vary across LIB types. Unlike lithium primary batteries (which are disposable), lithium-ion electrochemical cells use an intercalated lithium compound as the electrode material instead of metallic lithium.

 Lockheed lithium ion battery for NASA

Lithium-ion batteries are common in consumer electronics. They are one of the most popular types of rechargeable battery for portable electronics, with one of the best energy densities, no memory effect, and only a slow loss of charge when not in use. Beyond consumer electronics, LIBs are also growing in popularity for military, electric vehicle, and aerospace applications. Research is yielding a stream of improvements to traditional LIB technology, focusing on energy density, durability, cost, and intrinsic safety.

Charge and discharge

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

During charging, an external electrical power source (the charging circuit) applies a higher voltage (but of the same polarity) than that produced by the battery, forcing the current to pass in the reverse direction. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as intercalation.

Cylindrical 18650 lithium iron phosphate cell before closing

Construction

The three primary functional components of a lithium-ion battery are the anode, cathode, and electrolyte. The anode of a conventional lithium-ion cell is made from carbon, the cathode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent.

The most commercially popular anode material is graphite. The cathode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), a polyanion (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide).

The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate or diethyl carbonate containing complexes of lithium ions. These non-aqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate monohydrate (LiAsF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), and lithium triflate (LiCF3SO3).

Depending on materials choices, the voltage, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures using nanotechnology have been employed to improve performance.

Pure lithium is very reactive. It reacts vigorously with water to form lithium hydroxide and hydrogen gas. Thus, a non-aqueous electrolyte is typically used, and a sealed container rigidly excludes water from the battery pack.

Lithium ion batteries are more expensive than NiCd batteries but operate over a wider temperature range with higher energy densities, while being smaller and lighter. They are fragile and so need a protective circuit to limit peak voltages.

Formats 

Li-ion cells are available in various formats, which can generally be divided into four groups:

Small cylindrical (solid body without terminals, such as those used in laptop batteries) 
Large cylindrical (solid body with large threaded terminals) 
Pouch (soft, flat body, such as those used in cell phones) 
Prismatic (semi-hard plastic case with large threaded terminals, often used in vehicles' traction packs) 

The lack of case gives pouch cells the highest energy density; however, pouch cells (and prismatic cells) require an external means of containment to prevent expansion when their state-of-charge (SOC) level is high.

Varta lithium-ion battery, Museum Autovision, Altlussheim, Germany

History

Lithium batteries were first proposed by M.S. Whittingham, now at Binghamton University, while working for Exxon in the 1970s. Whittingham used titanium(II) sulfide as the cathode and lithium metal as the anode.

The reversible intercalation in graphite and intercalation into cathodic oxides was also already discovered in the 1970s by J.O. Besenhard at TU Munich. He also proposed the application as high energy density lithium cells. Electrolyte decomposition and solvent co-intercalation into graphite were severe drawbacks for long battery cycle life.

Primary lithium batteries in which the anode is made from metallic lithium pose safety issues. As a result, lithium-ion batteries were developed in which both anode and cathode are made of a material containing lithium ions.

In 1979, John Goodenough demonstrated a rechargeable cell with high cell voltage in the 4V range using lithium cobalt oxide (LiCoO2) as the positive electrode and lithium metal as the negative electrode. This innovation provided the positive electrode material which made LIBs possible. LiCoO2 is a stable positive electrode material which acts as a donor of lithium ions, which means that it can be used with a negative electrode material other than lithium metal. By enabling the use of stable and easy-to-handle negative electrode materials, LiCoO2 opened a whole new range of possibilities for novel rechargeable battery systems.

In 1977, Samar Basu demonstrated electrochemical intercalation of lithium in graphite at the University of Pennsylvania. This led to the development of a workable lithium intercalated graphite anode at Bell Labs (LiC6) to provide an alternative to the lithium metal battery.

In 1980, Rachid Yazami also demonstrated the reversible electrochemical intercalation of lithium in graphite. The organic electrolytes available at the time would decompose during charging if used with a graphite negative electrode, preventing the early development of a rechargeable battery which employed the lithium/graphite system. Yazami used a solid electrolyte to demonstrate that lithium could be reversibly intercalated in graphite through an electrochemical mechanism. The graphite anode discovered by Yazami is currently the most commonly used anode in commercial lithium ion batteries.

In 1983, Dr. Michael Thackeray, Goodenough, and coworkers identified manganese spinel as a cathode material. Spinel showed great promise, given its low-cost, good electronic and lithium ion conductivity, and three-dimensional structure, which gives it good structural stability. Although pure manganese spinel fades with cycling, this can be overcome with chemical modification of the material. Manganese spinel is currently used in commercial cells.

In 1985, Akira Yoshino assembled a prototype cell using carbonaceous material into which lithium ions could be inserted as the anode, and as the cathode lithium cobalt oxide (LiCoO2), which is stable in air. By using an anode material without metallic lithium, safety was dramatically improved over batteries which used lithium metal. The use of lithium cobalt oxide (LiCoO2) enabled industrial-scale production to be achieved easily.

This was the birth of the current lithium-ion battery.

Nissan Leaf's lithium-ion battery pack

Modern batteries

In 1991, Sony and Asahi Kasei released the first commercial lithium-ion battery.

In 1989, Goodenough and Arumugam Manthiram of the University of Texas at Austin showed that cathodes containing polyanions, e.g., sulfates, produce higher voltages than oxides due to the inductive effect of the polyanion.

In 1996, Goodenough, Akshaya Padhi and coworkers identified lithium iron phosphate (LiFePO4) and other phospho-olivines (lithium metal phosphates with the same structure as mineral olivine) as cathode materials.

In 2002, Yet-Ming Chiang and his group at MIT showed a substantial improvement in the performance of lithium batteries by boosting the material's conductivity by doping it with aluminium, niobium and zirconium. The exact mechanism causing the increase became the subject of widespread debate.

In 2004, Chiang again increased performance by utilizing iron phosphate particles of less than 100 nanometers in diameter. This decreased particle density almost one hundredfold, increased the cathode's surface area and improved capacity and performance. Commercialization led to a rapid growth in the market for higher capacity LIBs, as well as a patent infringement battle between Chiang and Goodenough.

As of 2011, lithium-ion batteries account for 67% of all portable secondary battery sales in Japan.

Electrochemistry

The three participants in the electrochemical reactions in a lithium-ion battery are the anode, cathode, and electrolyte.

Both the anode and cathode are materials into which, and from which, lithium can migrate. During insertion (or intercalation) lithium moves into the electrode. During the reverse process, extraction (or deintercalation), lithium moves back out. When a lithium-based cell is discharging, the lithium is extracted from the anode and inserted into the cathode. When the cell is charging, the reverse occurs.

Useful work can only be extracted if electrons flow through a closed external circuit. The following equations are in units of moles, making it possible to use the coefficient.

The overall reaction has its limits. Overdischarge supersaturates lithium cobalt oxide, leading to the production of lithium oxide, possibly by the following irreversible reaction:

Overcharge up to 5.2 Volts leads to the synthesis of cobalt(IV) oxide, as evidenced by x-ray diffraction

In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt (Co), in being oxidized from Co3+ to Co4+ during charging, and reduced from Co4+ to Co3+ during discharge.

Nokia Li-ion battery for powering a mobile phone

Positive electrodes

Electrode material Average potential difference Specific capacity Specific energy 
LiCoO2 3.7 V 140 mA·h/g 0.518 kW·h/kg 
LiMn2O4 4.0 V 100 mA·h/g 0.400 kW·h/kg 
LiNiO2 3.5 V 180 mA·h/g 0.630 kW·h/kg 
LiFePO4 3.3 V 150 mA·h/g 0.495 kW·h/kg 
Li2FePO4F 3.6 V 115 mA·h/g 0.414 kW·h/kg 
LiCo1/3Ni1/3Mn1/3O2 3.6 V 160 mA·h/g 0.576 kW·h/kg 
Li(LiaNixMnyCoz)O2 4.2 V 220 mA·h/g 0.920 kW·h/kg 
[edit] Negative electrodesElectrode material Average potential difference Specific capacity Specific energy 
Graphite (LiC6) 0.1-0.2 V 372 mA·h/g 0.0372-0.0744 kW·h/kg 
Hard Carbon (LiC6) ? V ? mA·h/g ? kW·h/kg 
Titanate (Li4Ti5O12) 1-2 V 160 mA·h/g 0.16-0.32 kW·h/kg 
Si (Li4.4Si)[38] 0.5-1 V 4212 mA·h/g 2.106-4.212 kW·h/kg 
Ge (Li4.4Ge)[39] 0.7-1.2 V 1624 mA·h/g 1.137-1.949 kW·h/kg 
[edit] ElectrolytesThe cell voltages given in the Electrochemistry section are larger than the potential at which aqueous solutions can electrolyze, in addition lithium is highly reactive to water, therefore, nonaqueous or aprotic solutions are used.

Liquid electrolytes in lithium-ion batteries consist of lithium salts, such as LiPF6, LiBF4 or LiClO4 in an organic solvent, such as ethylene carbonate, dimethyl carbonate, and diethyl carbonate. A liquid electrolyte conducts lithium ions, acting as a carrier between the cathode and the anode when a battery passes an electric current through an external circuit. Typical conductivities of liquid electrolyte at room temperature (20 °C (68 °F)) are in the range of 10 mS/cm (1 S/m), increasing by approximately 30–40% at 40 °C (104 °F) and decreasing by a slightly smaller amount at 0 °C (32 °F)

Unfortunately, organic solvents easily decompose on anodes during charging. However, when appropriate organic solvents are used as the electrolyte, the solvent decomposes on initial charging and forms a solid layer called the solid electrolyte interphase (SEI), which is electrically insulating yet provides sufficient ionic conductivity. The interphase prevents decomposition of the electrolyte after the second charge. For example, ethylene carbonate is decomposed at a relatively high voltage, 0.7 V vs. lithium, and forms a dense and stable interface.

A good solution for the interface instability is the application of a new class of composite electrolytes based on POE (poly(oxyethylene)) developed by Syzdek et al. It can be either solid (high molecular weight) and be applied in dry Li-polymer cells, or liquid (low molecular weight) and be applied in regular Li-ion cells.

Another issue that Li-ion technology is facing is safety. Large scale application of Li cells in Electric Vehicles needs a dramatic decrease in the failure rate. One of the solutions is the novel technology based on reversed-phase composite electrolytes, employing porous ceramic material filled with electrolyte.

Advantages and disadvantages

Note that both advantages and disadvantages depend on the materials and design that make up the battery. This summary reflects older designs that use carbon anode, metal oxide cathodes, and lithium salt in an organic solvent for the electrolyte.

Optima ACP TZERO tubular plate lead acid batteries

Advantages 

Wide variety of shapes and sizes efficiently fitting the devices they power. 

Much lighter than other energy-equivalent secondary batteries.

High open circuit voltage in comparison to aqueous batteries (such as lead acid, nickel-metal hydride and nickel-cadmium).[46] This is beneficial because it increases the amount of power that can be transferred at a lower current. 
No memory effect. 

Self-discharge rate of approximately 5-10% per month, compared to over 30% per month in common nickel metal hydride batteries, approximately 1.25% per month for Low Self-Discharge NiMH batteries and 10% per month in nickel-cadmium batteries. According to one manufacturer, lithium-ion cells (and, accordingly, "dumb" lithium-ion batteries) do not have any self-discharge in the usual meaning of this word. What looks like a self-discharge in these batteries is a permanent loss of capacity (see Disadvantages). On the other hand, "smart" lithium-ion batteries do self-discharge, due to the drain of the built-in voltage monitoring circuit. 

Components are environmentally safe as there is no free lithium metal.

Disadvantages - Cell life

Charging forms deposits inside the electrolyte that inhibit ion transport. Over time, the cell's capacity diminishes. The increase in internal resistance reduces the cell's ability to deliver current. This problem is more pronounced in high-current applications. The decrease means that older batteries do not charge as much as new ones (charging time required decreases proportionally). 

High charge levels and elevated temperatures (whether from charging or ambient air) hasten capacity loss. Charging heat is caused by the carbon anode (typically replaced with lithium titanate which drastically reduces damage from charging, including expansion and other factors).

Internal resistance

The internal resistance of standard (Cobalt) lithium-ion batteries is high compared to both other rechargeable chemistries such as nickel-metal hydride and nickel-cadmium, and LiFePO4 and lithium-polymer cells. Internal resistance increases with both cycling and age. Rising internal resistance causes the voltage at the terminals to drop under load, which reduces the maximum current draw. Eventually increasing resistance means that the battery can no longer operate for an adequate period. 

To power larger devices, such as electric cars, connecting many small batteries in a parallel circuit is more effective and efficient than connecting a single large battery.

Safety requirements

If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture.[56] In extreme cases this can lead to combustion. Deep discharge may short-circuit the cell, in which case recharging would be unsafe. To reduce these risks, Lithium-ion battery packs contain fail-safe circuitry that shuts down the battery when its voltage is outside the safe range of 3–4.2 V per cell. When stored for long periods the small current draw of the protection circuitry itself may drain the battery below its shut down voltage; normal chargers are then ineffective. Many types of lithium-ion cell cannot be charged safely below 0°C.

Other safety features are required in each cell:

Shut-down separator (for overtemperature) 
Tear-away tab (for internal pressure) 
Vent (pressure relief) 
Thermal interrupt (overcurrent/overcharging) 

These devices occupy useful space inside the cells, add additional points of failure and irreversibly disable the cell when activated. They are required because the anode produces heat during use, while the cathode may produce oxygen. These devices and improved electrode designs reduce/eliminate the risk of fire or explosion.

These safety features increase costs compared to nickel metal hydride batteries, which require only a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.

Specific energy density: 150 to 250 W·h/kg (540 to 900 kJ/kg)
Volumetric energy density: 250 to 620 W·h/l (900 to 1900 J/cm³)[2] 
Specific power density: 300 to 1500 W/kg (@ 20 seconds and 285 W·h/l)

Because lithium-ion batteries can have a variety of cathode and anode materials, the energy density and voltage vary accordingly.

Lithium-ion batteries with a lithium iron phosphate cathode and graphite anode have a nominal open-circuit voltage of 3.2 V and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide cathode with graphite anodes have a 3.7 V nominal voltage with a 4.2 V max charge. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less. Some lithium-ion varieties can reach 90% in as little as 10 minutes.

Battery charging procedure

The charging procedures for single Li-ion cells, and complete Li-ion batteries, are slightly different.

A single Li-ion cell is charged in 2 stages:

1. CC 
2. CV 

A Li-ion battery (a set of Li-ion cells in series) is charged in 3 stages:

1. CC

2. Balance (not required once a battery is balanced) 
3. CV

Stage 1: CC: Apply charging current to the battery, until the voltage limit per cell is reached.

Stage 2: Balance: Reduce the charging current (or cycle the charging on and off to reduce the average current) while the State Of Charge of individual cells is balanced by a balancing circuit, until the battery is balanced.

Stage 3: CV: Apply a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines asymptotically towards 0, until the current is below a set threshold of about 3% of initial constant charge current.

Variations in materials and construction

The increasing demand for batteries has led vendors and academics to focus on improving the power density, operating temperature, safety, durability, charging time, output power, and cost of LIB solutions.

A lithium-ion battery from a laptop computer

Usage guidelines - Prolonging battery pack life

Avoid deep discharge and instead charge more often between uses, the smaller the depth of discharge, the longer the battery will last.

Avoid storing the battery in full discharged state. As the battery will self-discharge over time, its voltage will gradually lower, and when it is depleted below the low-voltage threshold (2.4 to 2.9 V/cell, depending on chemistry) it cannot be charged anymore because the protection circuit (a type of electronic fuse) disables it.

Lithium-ion batteries should be kept cool; they may be stored in a refrigerator.

The rate of degradation of Lithium-ion batteries is strongly temperature-dependent; they degrade much faster if stored or used at higher temperatures.

Multicell devices

Li-ion batteries require a battery management system to prevent operation outside each cell's safe operating area (over-charge, under-charge, safe temperature range) and to balance cells to eliminate SOC mismatches, significantly improving battery efficiency and increasing overall capacity. As the number of cells and load currents increase, the potential for mismatch also increases. There are two kinds of mismatch in the pack: state-of-charge (SOC) and capacity/energy ("C/E") mismatch. Though SOC is more common, each problem limits pack capacity (mA·h) to the capacity of the weakest cell.

Safety

Lithium-ion batteries can rupture, ignite, or explode when exposed to high temperature. Short-circuiting a battery will cause the cell to overheat and possibly to catch fire. Adjacent cells may then overheat and fail, possibly causing the entire battery to ignite or rupture. In the event of a fire, the device may emit dense irritating smoke.

Replacing the lithium cobalt oxide cathode material in lithium-ion batteries with a lithium metal phosphate such as lithium iron phosphate, improves cycle counts, shelf life and safety, but lowers capacity. Currently, these 'safer' lithium-ion batteries are mainly used in electric cars and other large-capacity battery applications, where safety issues are critical.

Lithium-ion batteries normally contain safety devices to protect the cells from disturbance. However, contaminants inside the cells can defeat these safety devices.

Recalls

In March 2007, Lenovo recalled approximately 205,000 batteries at risk of explosion. In August 2007, Nokia recalled over 46 million batteries at risk of overheating and exploding. One such incident occurred in the Philippines involving a Nokia N91, which uses the BL-5C battery.

In December 2006, Dell recalled approximately 22,000 laptop batteries from the US market. Approximately 10 million Sony batteries used in Dell, Sony, Apple, Lenovo/IBM, Panasonic, Toshiba, Hitachi, Fujitsu and Sharp laptops were recalled in 2006. The batteries were found to be susceptible to internal contamination by metal particles. Under some circumstances, these particles could pierce the separator, causing a short-circuit.

In October 2004, Kyocera Wireless recalled approximately 1 million mobile phone batteries to identify counterfeits.

Transport restrictions

In January 2008, the United States Department of Transportation ruled that passengers on commercial aircraft could carry lithium batteries in their checked baggage if the batteries are installed in a device. Types of batteries affected by this rule are those containing lithium, including Li-ion, lithium polymer, and lithium cobalt oxide chemistries. Lithium-ion batteries containing more than 25 grams (0.88 oz) equivalent lithium content (ELC) are exempt from the rule and are forbidden in air travel. This restriction greatly reduces the chances of the batteries short-circuiting and causing a fire.

Additionally, a limited number of replacement batteries may be transported in carry-on luggage. Such batteries must be sealed in their original protective packaging or in individual containers or plastic bags.

Some postal administrations restrict air shipping (including EMS) of lithium and lithium-ion batteries, and products containing these (for example: laptops, cell phones). Among these countries and regions are Hong Kong, Australia and Japan.

Research

Researchers are working to improve the power density, safety, recharge cycle, cost and other characteristics of these batteries.

Solid-state designs  have the potential to deliver three times the energy density of typical 2011 lithium-ion batteries at less than half the cost per kilowatt-hour. This approach eliminates binders, separators, and liquid electrolytes. By eliminating these, "you can get around 95% of the theoretical energy density of the active materials." 

Earlier trials of this technology encountered cost barriers, because the semiconductor industry's vacuum deposition technology cost 20–30 times too much. The new process deposits semiconductor-quality films from a solution. The nano-structured films grow directly on a substrate and then sequentially on top of each other. The process allows the firm to "spray-paint a cathode, then a separator/electrolyte, then the anode. It can be cut and stacked in various form factors.

LINKS:

Automotive Development

Battery cartridges are the way to go for road cars. Lithium Ion batteries offer a much higher energy density and are ideal for extending the range between cartridge exchanges. See the pictures below for examples.

The world's fastest electric circuit racers need a system to recharge batteries instantly during pit stops. The Formula E concept design above incorporates the patent Bluebird™ instant energy transfer system - allowing EV refuelling in around 10 seconds. Get your free developer License from Bluebird Marine Systems Ltd. 

   LSR HISTORY

Lithium Polymer Suppliers and manufactures:

Kokam

Kokam possesses its own unique, proprietary technology (the Superior Lithium Polymer Battery or SLPB), which has proven marketability over existing and perceived competition. Substantial opportunities exist to tap into the market of cellular phone manufacturers and distributors who seek better lithium-ion batteries than those readily available on the market. The challenge is to bring cost-efficiency to the major channel members and OEMs, and Kokam has met this challenge. As more and more of the world's population have gained an interest in these products (as well as notebook computers and similar portable devices), the demand for lithium-ion batteries has also increased and will continue to increase over the next five years. Kokam's particular patented design employing the next generation lithium-ion/polymer technology, will increasingly occupy more and more of the total rechargeable battery sales in this industry. Based on its advanced technology and price competitiveness, Kokam's market share will be extended as fast as it is able to increase production capacity. The cellular phone industry represents very strong demand for this next generation technology, which far exceeds the overall industry's production capacity. Additionally, the size of market for notebook pc and PDA is being increased fast will be a great opportunity for Kokam. Kokam makes high standard and reliable re-chargeable Lithium battery and its processing equipments and also develop new advanced technologies for future.

http://www.kokam.com/english/biz/kokam.html

SANYO

SANYO has developed a lithium polymer battery that is ultra-thin (under 4mm) & ultra-light with superior performance, SANYO reliability, and new technology developed in our labs. Lithium polymer batteries employ a new gel-type electrolyte to provide power to the most demanding application in the hand-held world. Once again, SANYO has developed the answer to the demand for ultra-thin, ultra-light, high-power applications.

http://www.sanyo.com/batteries/lithpol.cfm

PowerStream

Lithium Polymer Batteries from PowerStream. Battery chargers, power supplies, dc to dc converters, custom, semi-custom and off-the-shelf

http://www.powerstream.com/li-pol.htm