As we all know, ternary lithium batteries or lithium iron phosphate power batteries used by road and non road vehicles are actually named according to their positive active materials.
In this paper, we compiled six common types of lithium batteries, together with their main performance parameters and performance. Generally speaking, the specific parameters of lithium battery cells with the same technical route are not exactly the same. As shown below, the general level of current parameters is shown.
Six types of lithium batteries include:
Lithium cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), lithium nickel cobalt manganate (linimncoo2 or NMC), lithium nickel cobalt aluminate (linicoalo2 or NCA), lithium iron phosphate (LiFePO4), lithium titanate (Li4Ti5O12).
1. Lithium cobalt oxide (LiCoO 2)
Lithium cobaltate is an inorganic compound with the chemical formula LiCoO З, which is generally used as the positive electrode material of lithium-ion battery. Its appearance is grayish black powder. Inhalation and skin contact can cause allergy. Chinese alias: lithium cobaltate; Lithium cobalt (III) oxide
Generally used in lithium ion two battery cathode material [1], liquid phase synthesis process, it uses polyvinyl alcohol (PVA) or polyethylene glycol (PEG) aqueous solution as solvent, lithium salt and cobalt salt are dissolved in PVA or PEG aqueous solution respectively. After mixing, the solution is heated to form gel, then the gel is decomposed and then calcined at high temperature.
Its high specific energy ratio makes lithium cobalt oxide a popular choice for mobile phones, laptops and digital cameras. The battery consists of cobalt oxide cathode and graphite carbon anode. The cathode has a layered structure. During the discharge, lithium ions move from the anode to the cathode, and the flow direction is opposite during the charging process. The structural form is shown in Figure 1.
The cathode has a layered structure. During the discharge, lithium ions move from the anode to the cathode; During charging, the flow flows from the cathode to the anode.
As a popular cathode in portable devices, lithium cobalt oxide provides only half of its theoretical capacity in commercial lithium-ion batteries. When the cut-off voltage is increased to release more capacity, the dissolution of cobalt in the electrolyte and the structural disorder of lithium cobaltate particles are serious, resulting in rapid capacity attenuation and limited cycle life. Here, we show a kind of lithium cobalt oxide modified by ternary lithium, aluminum and fluorine. It uses simple and scalable hydrothermal assisted mixed surface treatment and has a stable conductive layer. This surface treatment hinders the direct contact between the liquid electrolyte and lithium cobaltate particles, thereby reducing the loss of active cobalt. It also forms a thin doped layer composed of lithium aluminum cobalt oxide fluorine solid solution,
Since Sony first commercialized the rechargeable lithium-ion battery (LIB) in 1991, the rechargeable lithium-ion battery (LIB) has been widely used in various portable electronic 名媛直播 and recently in large electric vehicles (EV) and energy storage grid (EEG). Due to their rapid development in industrial applications, lib1,2,3,4 with higher energy density and higher power output are needed. The most prominent cathode materials are based on the crystal structures of layered, spinel and olivine structures, which are composed of cobalt lithium, nickel and manganese based oxides or polyanionic materials 3 and 5.
Among various cathode materials, lithium cobalt oxide (LiCoO2, LCO) is due to its ordered structure α- Nafeo2 layered structure is used to manufacture > 31% lib, which makes the production easy to expand and fast reversible lithium intercalation 3,6 Specifically, LCO has a high theoretical capacity of 274 MAH g-1, but the actual discharge capacity is only ~ 140 MAH g-1 (Li1 ? xcoo2, X ≈ 0.5, ~ 4.2 V vs. Li / Li +) 7,8 The fundamental reason for such a large capacity shortage is the phase transition from hexagonal phase to monoclinic phase, and the starting voltage is ~ 4.2 v8,9. Extracting lithium to a concentration of more than 0.5 mol will lead to structural instability, limiting the cut-off voltage of lithium de intercalation to 4.2 v. When the voltage is > 4.2 V, the cycle efficiency and discharge capacity of LCO battery will decay rapidly.
Lithium cobalt oxide is excellent in high specific energy, but it can only provide general performance in power characteristics, safety and cycle life
2. Lithium manganate (LiMn2O4)
Lithium manganate battery refers to a battery with lithium manganate as negative electrode material. Its nominal voltage is 3.7V. It is the mainstream power battery at present. The battery has ordinary energy density and cycle life. Environmental protection, no patent restrictions. However, lithium manganate is not very stable and is easy to decompose gas, which may lead to swelling and poor high-temperature performance.
Lithium manganate, whose chemical formula is LiMn2O4 (LCM), is a promising lithium ion cathode material. Compared with traditional cathode materials such as lithium cobalt oxide, lithium manganate has rich resources, low cost, no pollution, good safety and good rate performance. It is an ideal cathode material for power battery.
Lithium manganate tends to be spinel type. LiMn2O4 spinel lithium manganate is the first cathode material with 3D lithium ion channel manufactured by hunter in 1981. So far, it has attracted the attention of many scholars and researchers at home and abroad. As an electrode material, it has the advantages of low price, great potential, environmental friendliness and good safety performance. It is the most promising cathode material for a new generation of lithium ion battery to replace LiCoO2.
LMO battery positive
The main components of lithium manganate are spinel lithium manganate and layered lithium manganate. The lithium manganate model of spinel structure belongs to cubic system, which is an fd3m space group. At present, the structure of high-capacity lithium manganate cathode material is reasonable. Lithium ion can easily and reversibly leave the spinel lattice, because the structure is relatively safe, there is no risk of structural collapse, and the safety of the product is guaranteed.
1. The theoretical capacity of layered LiMnO2 is 285ma · H / g and the voltage platform is 4V. The layered structure is difficult to synthesize and unstable. It is easy to form spinel structure li2mn2o4, resulting in voltage platform drop, poor stability and irreversible capacity attenuation.
2. The theoretical capacity of high voltage spinel LiMn2O4 is 148ma · H / g, and the voltage platform is 4.15. Its high temperature performance is poor, and its capacity attenuation is serious above 55 ℃. Li2mn2o4 with spinel structure is easy to produce, which leads to the decline of voltage platform, poor stability and irreversible capacity attenuation. This is the lithium manganate oxide used in industry at present.
3. Spinel li2mn2o4 has low voltage of 3V, low capacity and poor circulation. People are studying how to avoid these problems.
LMO battery composition
Lithium manganate battery is a lithium-ion battery with lithium manganate as anode, graphite as cathode and LiPF6 organic solution as electrolyte. Its nominal voltage is 3.7V. The structure of lithium manganate battery packed with aluminum shell is shown in the figure below:
Lithium manganate cathode crystallizes to form a three-dimensional skeleton structure formed after formation. Spinel provides low resistance, but its specific energy is lower than that of lithium cobalt oxide.
The capacity of lithium manganate is about one third lower than that of lithium cobalt oxide. Design flexibility enables engineers to choose to maximize the service life of the battery or increase the maximum load current (specific power) or capacity (specific energy). For example, the long-life version of 18650 battery has only a moderate capacity of 1100mah; The high-capacity version reaches 1500mah.
Figure 5 shows a spider diagram of a typical lithium manganate battery. These characteristic parameters do not seem ideal, but the new design has improved in power, safety and life. Pure lithium manganate batteries are no longer common today; They are only used in special cases.
Although the overall performance is average, the new lithium manganate design can improve power, safety and service life.
Lithium manganate has the advantages of good rate performance, easy preparation and low cost. The disadvantage is that the dissolution of manganese leads to poor high-temperature performance and cycle performance. By doping aluminum and sintering granulation, the high temperature performance and cycle performance are greatly improved, which can basically meet the actual use. In general, lithium manganate battery has low cost, good stability and good low-temperature performance, but poor high-temperature performance and slightly faster attenuation.
The negative electrode material has the advantages of low cost, good safety and good low-temperature performance, but the material itself has poor stability and is easy to decompose to produce gas. Therefore, it tends to be mixed with other materials to reduce the cost of the battery. However, the cycle life decays rapidly and is prone to bulge. Its high temperature performance is poor and its cycle life is short. It is mainly used for large and medium-sized batteries and power batteries. The nominal voltage is 3.7 v.
Lithium manganate is a promising lithium ion cathode material. Compared with traditional cathode materials such as lithium cobalt oxide, lithium manganate has the advantages of rich resources, low cost, no pollution, good safety and good rate performance. It is an ideal cathode material for power batteries. Therefore, lithium battery electrode materials, especially the new generation of lithium manganate cathode materials, have great potential in the electric vehicle power battery market. Due to its low price and rich resources, lithium manganate is easier to produce than lithium cobalt oxide and lithium nickel oxide, which will bring lithium-ion batteries into a new era of development.
Because lithium manganate material has such distinctive characteristics, people will make use of its advantages and avoid its disadvantages. Therefore, lithium manganate batteries are used in different fields, commonly referred to as class A and class B applications.
Class a refers to the power battery, focusing on safety and recycling performance. It is required to have a workable capacity of 100 ~ 115mah / g
Lithium manganate battery is a battery with lithium manganate anode. The nominal voltage of lithium manganate battery is 2.5 ~ 4.2V. Lithium manganate battery is widely used because of its low cost and good safety.
Lithium manganate battery has low cost, good safety and good low-temperature performance, but the material itself has poor stability and is easy to decompose to produce gas. Therefore, it tends to be used with other materials to reduce the cost of the battery. However, the cycle life decay is fast, easy to bulge, poor high-temperature performance and short service life. It is mainly used for large and medium-sized batteries and power batteries. Its nominal voltage is 3.7 v.
3. Lithium nickel cobalt manganate (linimncoo 2 or NMC)
Lithium nickel manganese cobalt oxide (Li NMC, lnmc, NMC or NCM for short) is a mixed metal oxide of lithium, nickel, manganese and cobalt. Their general formula is linixmnycozo2. The most important representative has an X + y + Z composition close to 1, with a small amount of lithium at the transition metal site. In commercial NMC samples, the composition typically has < 5% excess lithium. [1] [2] the structural materials in this group are closely related to lithium cobalt (III) oxide (LiCoO2) and have layered structure, but have ideal Mn (IV), CO (III) and Ni (II) charge distribution at 1: 1 stoichiometric ratio. For more nickel rich compositions, nickel is in a more oxidized state to achieve charge balance. NMCS is one of the most important lithium ion storage materials in lithium ion batteries. They are used as positive electrodes and act as cathode during discharge.
history
The stoichiometric NMC cathode is expressed as a point in the solid solution between the end elements LiCoO2, LiMnO2 and LiNiO2. They are historically derived from John B. goodenoughs' research on LiCoO2 in the 1980s, tsutomo ohzuku's research on Li (NiMn) O2 and related research on nafeo2 materials. Related to stoichiometric NMC, lithium rich NMC materials were first reported in 1998. Their structure is similar to cobalt (III) lithium oxide (LiCoO2), but stabilized by excess lithium, Li / NMC > 1.0, which is manifested as 2mno3 nano domains in a series of Li materials. These cathodes were first reported by CS Johnson, JT vaughey, mm Thackeray, te Bofinger and SA hackney. For both types of NMC cathodes, there is a formal internal charge transfer, manganese oxide and reduction of nickel cations, rather than all transition metal cations are trivalent. The two electron oxidation of nickel (II) in the form of charge contributes to the high capacity of these NMC cathode materials. In 2001, arumughan mantiram assumed that the mechanism of creating high capacity for layered oxide cathode was produced by a transformation, which can be understood according to the relative position of metal 3D band relative to the top of oxygen 2p band. This observation helps to explain the high capacity of the NMC positive electrode, because above 4.4 V (relative to lithium), it has been found that some of the observed capacities are caused by the oxidation of the oxide lattice rather than cationic oxidation.
In 2001, Christopher Johnson, Michael Thackeray, Khalil amine and jaekook Kim applied for a patent for lithium nickel manganese cobalt oxide (NMC) lithium rich cathode based on li2mno3 derived domain structure. In 2001, Lu Zhonghua and Jeff Dahn applied for a patent for NMC cathode materials based on the solid solution concept between end elements.
Metal ratio
Several different levels of nickel have commercial value. The ratio between the three metals is represented by three numbers. For example, lini0 333 manganese 0.333 cobalt 0.333 ? 2, abbreviated as nmc111 or nmc333, lini0 5 manganese 0.3 cobalt 0.2 ? 2 to lini0 of nmc532 (or ncm523) 6 manganese 0.2 cobalt 0.2 ? 2 to nmc622 and lini0 8 manganese 0.1 cobalt 0.1 oxygen 2 to nmc811. Given the potential problems of cobalt procurement, there is interest in increasing the nickel content, although this will reduce thermal stability.
Although lithium carbonate or lithium hydroxide can be used in nmc111, lithium hydroxide is required to manufacture nmc811 because lower synthesis temperature helps to reduce lithium / nickel site exchange, which is related to reduced performance.
Use of NMC electrode
Audi e-tron Sportback
Most electric vehicles use NMC batteries. NMC battery was installed on BMW ActiveE in 2011 / 2011 and on BMW I8 since 2013. [14] By 2020, electric vehicles with NMC batteries include: Audi e-tron Ge, BAIC EU5 r550, BMW I3, BYD ev535, Chevrolet bolt, Hyundai Kona electric, Jaguar i-pace, JMC e200l, Weilai ES6, Nissan LEAF s plus, Renault Zoe, Roewe ei5, Volkswagen e-Golf and Volkswagen id.3. [15] Only a few electric vehicle manufacturers do not use NMC in their traction batteries. The most important exception is Tesla, which uses NCA's vehicle batteries. However, Tesla Powerwall for home storage is said to be [according to who?] Based on NMC.
NMC is also used in mobile electronic 名媛直播, such as mobile phones / smartphones, laptops in most electric bicycle batteries. For these applications, almost only lithium cobalt oxide LCO batteries were used in 2008. [19] Another application of NMC battery is battery energy storage power station. For example, in Korea, two energy storage systems with NMC for frequency regulation were installed in 2016: one with capacity of 16 MW and energy of 6 MWh, and the other with capacity of 24 MW and 9 MWh. [20] In 2017 / 2018, more than 30 MW capacity and 11 MW hours of batteries were installed and commissioned in Newman, Western Australia.
Characteristics of NMC electrode
The battery voltage of lithium ion battery with NMC is 3.6-3.7 v. [23] manthiram found that the capacity limitation of these layered oxide cathodes is the result of chemical instability, which can be understood according to the relative position of the relative position of the metal 3D band. To the top of the oxygen 2p band. This discovery is of great significance to the practical accessible composition space of lithium-ion battery and its stability from the perspective of safety.
NMC has good overall performance and excellent performance in specific energy. This battery is the first choice for electric vehicles and has the lowest self heating rate.
Due to the good economy and comprehensive performance of the system, NMC hybrid lithium-ion battery has attracted more and more attention. Nickel, manganese and cobalt can be easily mixed to adapt to the wide application of automobile and energy storage system (EES) requiring frequent cycling. The diversity of the NMC family is growing.
4. Lithium iron phosphate (LiFePO)
In 1996, the University of Texas found that phosphate could be used as cathode material for rechargeable lithium batteries. Lithium phosphate has good electrochemical properties and low resistance. This is achieved through nano phosphate cathode materials. The main advantages are high rated current and long cycle life; Good thermal stability, enhanced safety and tolerance to abuse.
Lithium iron phosphate is a compound LiFePO4 or "LFP" for short. LFP has good electrochemical performance and low resistance. It is one of the safest and most stable cathode materials for lithium-ion batteries.
What is lithium iron phosphate battery?
Lithium iron phosphate battery is a kind of lithium-ion battery which uses lithium iron phosphate as cathode material to store lithium ions. LFP batteries usually use graphite as negative electrode material. The chemical composition of LFP batteries makes them have high rated current, good thermal stability and long life cycle.
Most lithium iron phosphate batteries have four battery cells in series. The nominal voltage of LFP battery is 3.2 volts. Connecting four LFP batteries in series produces a 12 volt battery, which is an excellent alternative to many 12 volt lead-acid batteries.
Lithium iron phosphate vs. Alternative lithium ion type
Lithium iron phosphate is just one of many lithium-ion batteries. Different kinds of lithium-ion batteries can be made by changing the compounds of the cathode. Some of the most common choices are lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel cobalt aluminum oxide (NCA), lithium nickel manganese cobalt oxide (NMC), and lithium titanate (LTO).
Each of these battery types has different advantages and disadvantages, making it very suitable for different applications. Looking at the main characteristics of these battery types, we can see the location of lithium iron phosphate batteries and which applications they are most suitable for.
energy density
Among other lithium ion types, LFP batteries have one of the highest specific power ratings. In other words, high specific power means that LFP batteries can provide a large amount of current and power without overheating.
On the other hand, it is important to remember that LFP batteries have the lowest specific energy level. Low specific energy means that the energy storage capacity per unit weight of LFP battery is lower than that of other lithium-ion batteries. This is usually not a big problem because the capacity of the battery pack can be increased by paralleling multiple batteries. This may not be ideal for applications that require very high energy density in very light spaces, such as pure electric vehicles.
Battery life cycle
The life of lithium iron phosphate battery starts from about 2000 complete discharge cycles and increases according to the discharge depth. The battery cells and internal battery management system (BMS) used by dragonfly energy have been tested for more than 5000 complete discharge cycles while retaining 80% of the original battery capacity.
The lifetime of LFP is second only to lithium titanate. However, LTO batteries have always been the most expensive lithium-ion battery option, which makes them too expensive for most applications.
Discharge rate
The discharge rate is measured as a multiple of the battery capacity, which means that the 1C discharge rate of 100Ah battery is 100A continuous. Commercially available LFP batteries traditionally have a continuous discharge rating of 1C, but may exceed this rating in a short time depending on the battery management system.
The LFP battery itself can usually safely provide a short 25C discharge. The ability to exceed 1C allows you to use LFP batteries in high-power applications that may have startup spikes in current consumption.
working temperature
LFP battery will not enter thermal runaway state until about 270 ℃. Compared with other common lithium-ion battery options, LFP battery has the second highest operating temperature limit.
Exceeding the temperature limit of lithium-ion battery will cause damage and may lead to thermal runaway, which may lead to fire. The high operating limit of LFP significantly reduces the possibility of thermal runaway events. The combination of LFP and high-quality BMS can turn off the battery before these conditions (about 57 ℃), which has a significant safety advantage.
Security advantage
LFP battery is one of the stable chemical components in all lithium ion options. This stability makes them one of the safest choices for consumer and industrial applications.
The only other relatively safe option is lithium titanate, which is usually too expensive and in most cases cannot operate at the correct voltage to replace 12V.
Lithium phosphate has good safety and long life, moderate specific energy and enhanced self discharge ability.
5. Lithium nickel cobalt aluminate (linicoalo2 or NCA)
Lithium nickel cobalt aluminate battery or NCA has been used since 1999. It has high specific energy, good specific power and long service life, which is similar to NMC. Less desirable are security and cost. Figure 11 summarizes six key features. NCA is the further development of lithium nickel oxide; Adding aluminum gives the battery better chemical stability.
Lithium nickel cobalt aluminum oxide (NCA) is a group of metal oxides containing substances. Some of them are important because of their applications in lithium-ion batteries. NCA is used as an active material on the positive electrode (the cathode when the battery is discharged). NCA is a mixed oxide of cations containing the chemical elements lithium, nickel, cobalt and aluminum. The most important representative is the general formula linixcoyalzo2 and X + y + Z = 1 If NCA contains batteries currently available on the market, these batteries are also used in electric vehicles and appliances, X ≈ 0.8, and the voltage of these batteries is between 3.6 V and 4.0 V, and the nominal voltage is 3.6 V or 3.7 v. One oxide currently used in 2019 is lini0,84co0,12al0,04o2.
NCA batteries: manufacturer and use
The most important manufacturer of NCA batteries is Panasonic or its partner Tesla, because Tesla uses NCA as an active material in the traction batteries of its models. In Tesla Model 3 and Tesla Model x, lini0,84co0,12al0,04o2 is used. With a few exceptions, current electric vehicles use NCA or lithium nickel manganese cobalt oxide (NMC) as of 2019. In addition to electric vehicles, NCA is also used for batteries of electronic equipment, mainly through Panasonic, Sony and Samsung cordless vacuum cleaners, which are also equipped with NCA batteries.
NCA manufacturer
NCA's main producers and their market share in 2015 were Sumitomo Metal Mining, accounting for 58%, toda industry (BASF) accounting for 16%, Japanese chemical industry accounting for 13% and ecopro accounting for 5%. [6] Sumitomo supplies to Tesla and Panasonic, and can produce 850 tons of NCA per month in 2014. [8] Sumitomo increased its monthly production capacity to 2550 tons in 2016 and 4550 tons in 2018. [8] In China, in Qinghai Province, Tongren County, the plant has been under construction since 2019 and will produce 1500 tons of NCA per month in the initial stage.
NCA attributes
The available charge storage capacity of NCA is about 180 to 200 MAH / g. [11] This is much lower than the theoretical value; For lini0,8co0,15al0,05o2, this is 279 MAH / g. [1] However, the capacity of NCA is significantly higher than that of alternative materials, such as lithium cobalt oxide licoo2148 MAH / g, lithium iron phosphate lifepo4165 MAH / g and NMC 333 lini0,33mn0, 33co0,33o2 with 170 MAH / g. [1] Licoo2nmc and NCA are cathode materials with layered structure. Due to the high voltage, NCA makes the battery have high energy density. Another advantage of NCA is its excellent fast charging ability. The disadvantage is the high cost of cobalt and nickel and limited resources.
The two materials NCA and NMC have related structures, very similar electrochemical behavior and show similar properties, especially relatively high energy density and relatively high properties. It is estimated that the NCA battery of model 3 contains 4.5 to 9.5 kilograms of cobalt and 11.6 kilograms of lithium.
Lithium nickel oxide LiNiO2 closely related to NCA, or nickel oxide nio2 itself, cannot be used as battery material because of its mechanical instability, rapid capacity loss and safety problems.
Nickel rich NCA: advantages and limitations
NCAs linixcoyalzo2x ≥ 0.8 is called nickel rich; [13] These compounds are the most important variants in the substance category. The nickel rich variant also has a low cobalt content and therefore has a cost advantage because cobalt is relatively expensive. In addition, with the increase of nickel content, the voltage will also increase, so the energy that can be stored in the battery will also increase. However, with the increase of nickel content, the risk of thermal decomposition and premature aging of batteries will also increase. When a typical NCA battery is heated to 180 ° C, it will get out of thermal control. [14] If the battery has been overcharged before, thermal runaway will occur even at 65 ° C. [14] Aluminum ions in NCA increase stability and safety, but they reduce capacity because they themselves are not involved in oxidation and reduction.
Material improvement
In order to make NCA more resistant, especially for batteries that need to operate at temperatures above 50 ° C, NCA active materials are usually coated. The coatings demonstrated in the study may contain fluoride, such as aluminum fluoride AlF3, crystalline oxides (e.g. coo2, TiO2, NMC) or glassy oxides (silica, SiO2) or phosphates (e.g. FePO4).
High energy and power density and good service life make NCA a candidate for EV Power System. High costs and marginal safety have a negative impact.
6. Lithium titanate (Li4Ti5O12)
Lithium titanate (LTO) battery is a rechargeable battery. Its advantage is that it charges faster than other lithium-ion batteries, but its disadvantage is that the energy density is much lower.
Titanate batteries are used in Mitsubishi's i-MiEV [3] electric vehicle, and Honda uses them in its EV Neo electric bicycle and fit electric vehicle. They are also used in Tosa concept electric buses. Due to its high level of safety and charging capacity, LTO batteries are used in automotive audio applications and mobile medical devices. The s-pen equipped with Samsung Galaxy note 20 ultra 5g also uses LTO battery.
According to an article by weatherflow, the tempest weather station equipment includes a 1300mAh LTO battery, which is charged through four solar panels and requires "at least four hours of sufficient sunshine every two weeks".
Chemistry
Lithium titanate battery is an improved lithium-ion battery. Lithium titanate nanocrystals are used on its anode surface instead of carbon. This makes the surface area of the anode about 100 square meters per gram, while the surface area of carbon is 3 square meters per gram, allowing electrons to quickly enter and leave the anode. This makes fast charging possible and provides high current when needed. Lithium titanate battery can also last 3000 to 7000 charging cycles; One source claimed that when charging and discharging at 55 ℃ (131 ° f) instead of the standard 25 ℃ (77 ° f), the cycle life reached about 1000 times to reach 80% of the capacity.
One disadvantage of lithium titanate batteries is that their inherent voltage is low (2.4V), which leads to lower specific energy (about 30-110 WH / kg) than traditional lithium-ion battery technology, which has an inherent voltage of 3.7V, although some lithium titanate batteries are said to have an energy density of 177 WH / L.
Lithium titanate anode batteries have been known since the 1980s. Lithium titanate replaces graphite in the anode of a typical lithium-ion battery, and the material forms a spinel structure. The cathode can be lithium manganate or NMC. The nominal battery voltage of lithium titanate is 2.40v, which can be charged quickly and provide high discharge current of 10C. It is said that the number of cycles is higher than that of conventional lithium-ion batteries. Lithium titanate is safe and has excellent low-temperature discharge characteristics. It can obtain 80% capacity at - 30 ° C (- 22 ° f).
LTO (usually Li4Ti5O12) has zero strain, no SEI film formation and no lithium plating phenomenon during rapid charging and low-temperature charging, so it has better charge and discharge performance than the traditional cobalt doped Li ion and graphite anode. The thermal stability at high temperature is also better than other lithium ion systems; However, batteries are expensive. The specific energy is low, only 65wh / kg, which is equivalent to NiCd. Lithium titanate is charged to 2.80v and 1.80v at the end of discharge. Figure 13 shows the characteristics of lithium titanate battery. Typical uses are electric power transmission system, ups and solar street lamp.
Lithium titanate is excellent in safety, low temperature performance and service life. Efforts are being made to increase specific energy and reduce costs.
The specific energies based on lead, nickel and lithium systems were compared. Although lithium aluminum (NCA) is a clear winner by storing more capacity than other systems, it is only suitable for power use in specific scenarios. Lithium manganate (LMO) and lithium phosphate (LFP) are excellent in terms of specific power and thermal stability. Lithium titanate (LTO) may have a low capacity, but it has a longer life than most other batteries and has the best low-temperature performance.
NCA enjoys the highest specific energy; However, lithium manganate and lithium iron phosphate are superior in specific power and thermal stability. Lithium titanate has the best service life.
