Six common types of lithium batteries and their main performance parameters

We often talk about ternary lithium batteries or lithium iron batteries, which are named for lithium batteries after cathode active materials. This paper summarizes the six common lithium battery types and their main performance parameters. As we all know, the same technical route of the cell, the specific parameters are not exactly the same, this paper shows the general level of the current parameters. The six lithium batteries include: lithium cobalt oxide (LiCoO2), lithium manganese manganate (LiMn2O4), lithium nickel-cobalt manganate (LiNiMnCoO2 or NMC), lithium nickel-cobalt aluminate (LiNiCoAlO2 or NCA), lithium iron phosphate (LiFePO4) and lithium titanate (Li4Ti5O12).

Lithium cobalt oxide (LiCoO2) Its high specific energy makes lithium cobalt oxide a popular choice for mobile phones, laptops and digital cameras. The battery consists of a cobalt-oxide cathode and a graphite-carbon anode. The cathode has a layered structure, during which lithium ions move from anode to cathode, and the charging process flows in the opposite direction. The cathode has a layered structure. During discharge, lithium ions move from anode to cathode; flow from the cathode to the anode during charging. The disadvantages of lithium cobalt oxide are its relatively short life, low thermal stability and limited load capacity (specific power). Like other cobalt hybrid lithium-ion batteries, lithium cobalt oxide uses graphite anode, and its cycle life is mainly limited by the solid electrolyte interface (SEI), mainly reflected in the gradual thickening of the SEI film, and the anode lithium plating in the process of fast charging or low temperature charging process. Newer material systems add nickel, manganese and / or aluminum to improve life, load capacity and reduce costs. Lithium cobalt oxide shall not be charged and discharged at a current higher than the capacity. This means that the 18,650 batteries with 2,400mAh can only be charged and discharged at less than or equal to 2,400mA. Forced rapid charging or applying a load higher than 2400mA can cause overheating and overload stress. For optimal fast charging, the manufacturer recommends a charge multiplier of 0.8C or about 2,000mA. The battery protection circuit limits the charging and discharge rates of the energy unit to a safety level of about 1C.

Lithium manganate (LiMn2O4) lithium spinel manganate battery was first published in 1983. In 1996, Moli Energy commercialized lithium-ion batteries with lithium manganese oxide as a cathode material. The architecture forms a 3-dimensional spinel structure that improves the ion flow on the electrode and, thereby reducing the internal resistance and improving the current carrying capacity. Another advantage of spinel is its high thermal stability, improved safety, but limited cycling and calendar life. Low battery internal resistance enables fast charging and high current discharge. Type 18650 cells, lithium manganate batteries can discharge at a current of 20-30A, with a moderate heat accumulation. Up to 50A1 second load pulse can also be applied. The constant high load at this current causes the heat to build up, and the battery temperature cannot exceed 80°C (176°F). Lithium manganate is used in electric tools, medical devices, as well as hybrid and pure electric vehicles. Lithium manganate is about a third less powerful than lithium cobalt oxide. Design flexibility allows engineers to choose to maximize the battery life, or to increase the maximum load current (specific power) or capacity (specific energy). For example, the long-life version of the 18650 battery only has only a modest capacity of 1,100mAh; the high-capacity version has 1,500mAh.

Most lithium manganese oxide is mixed with lithium nickel-manganese cobalt oxide (NMC) to increase specific energy and extend life. This combination delivers the best performance for each system, and most electric vehicles, such as the Nissan Leaf, the Chevrolet Volt, and the BMW i3, have the LMO (NMC). The LMO part of the battery can reach about 30%, which can provide a high current when accelerating; and the NMC part provides a long range. Lithium-ion battery studies tend to combine lithium manganese oxide with cobalt, nickel, manganese, and / or aluminum as active cathode materials. In some architectures, a small amount of silicon is added to the anode. This provides a 25% capacity increase; however, silicon expands and contracts with charge and discharge, causing mechanical stress, and the capacity increase is often closely associated with a short cycle life. These three active metals and silicon enhancement can be easily selected to improve the specific energy (capacity), specific power (load capacity) or life. Consumer batteries require large capacity, while industrial applications require battery systems, with good load capacity, long life, and provide safe and reliable services.

One of the most successful lithium-ion systems of lithium-nickel-cobalt-manganese-manganate (LiNiMnCoO2 or NMC) is the cathode combination of nickel-nickel-manganese-cobalt (NMC). Similar to lithium manganate, the system can be customized as an energy battery or a power battery. For example, the NMC in a 18650 battery under medium load conditions has a capacity of about 2,800mAh and can provide 4A to 5A discharge currents; the same type of NMC is optimized for a specific power with a capacity of only 2,000mAh, but can provide a continuous discharge current of 20A. The silicon-based anode will reach more than 4000mAh, but the load capacity is reduced and the cycle life is shortened. The silicon added to the graphite has a defect, that is, the anode expands and contracts with charging and discharge, making the large mechanical stress structure of the battery unstable. The secret of the NMC is the combination of nickel and manganese. Like this is table salt, where the main ingredients of sodium and chloride are themselves toxic, but they are mixed as flavoring salts and food preservation agents. Nickel is known for its high specific energy, but has poor stability; the manganese spinel structure achieves low internal resistance but lower specific energy. The two active metals have complementary advantages. NMC is the battery of choice for electric tools, electric bikes and other electric powertrain. Cathodic combinations are usually one third nickel, third manganese and third cobalt, also known as 1-1-1. This provides a unique mixture that also reduces raw material costs due to reduced cobalt content. Another successful combination was the NCM, which contained 5 parts of nickel, 3 parts of cobalt, and 2 parts of manganese (5 – 3-2). Other combinations of different amounts of cathode materials may also be used. Due to the high cost of cobalt, battery manufacturers switched from cobalt to nickel cathode. Nickel-based systems have a higher energy density, a lower cost, and a longer cycle life than cobalt-based batteries, but they have slightly lower voltages.

Lithium iron phosphate (LiFePO 4) In 1996, the University of Texas found that phosphate could be used as a cathode material for rechargeable lithium batteries. Lithium phosphate has good electrochemical properties and a low resistance. This is achieved by using a nanoscale phosphate cathode material. The main advantages are high rated current and long cycle life; good thermal stability, enhanced safety and abuse tolerance. If maintained at high voltage for long periods, lithium phosphate is more tolerant to all charging conditions and is less stressed than other lithium-ion systems. The disadvantage is that the lower 3.2V battery nominal voltage makes the specific energy lower than cobalt doped lithium ion batteries. For most batteries, low temperatures reduce performance, increasing storage temperatures shorten service life, and lithium phosphate is no exception. Lithium phosphate has a higher self-discharge than other lithium-ion batteries, which can cause aging and further balancing problems, which can be made up for by using high-quality batteries or using advanced battery management systems, but both methods increase the cost of the battery pack. Battery life is very sensitive to the impurities in the manufacturing process, and cannot withstand the doping of water. Due to the existence of water impurities, some batteries have a minimum life of only 50 cycles. Figure 9 summarizes the properties of lithium phosphate. Lithium phosphate is commonly used instead of lead-acid starter batteries. The four series cells produced 12.80V, with a similar voltage to the six 2V lead-acid cells in series. The vehicle charges the lead acid to the 14.40V(2.40V/ battery) and remains floating charged. The purpose of the floating charge is to maintain the full charging level and prevent the sulfation of the lead-acid batteries.

Lithium nickel-cobalt aluminate (LiNiCoAlO2 or NCA) lithium nickel-cobalt aluminate batteries or NCA have been applied since 1999. It has a high specific energy, quite good specific power and long service life is similar to the NMC. Less flattering is security and cost.

Lithium titanate (Li4Ti5O12) Lithium titanate anode batteries have been known since the 1980s. Lithium titanate replaces the 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. Lithium titanate has a nominal battery voltage of 2.40V, which can be quickly charged, and provides a high discharge current of 10C. The number of cycles are said to be higher than those of conventional lithium-ion batteries. Lithium titanate is safe and has excellent low-temperature discharge properties, achieving 80% of the capacity at the-30°C (-22°F). LTO (usually Li4Ti5O12) has zero strain, no SEI membrane formation and no lithium electroplating phenomenon during fast charging and low temperature charging, so it has the better charge-discharge performance of the traditional cobalt mixed Li-ion and graphite anode. Thermal stability at high temperatures is also better than other lithium-ion systems; however, batteries are expensive. The specific energy is low, only 65Wh / kg, comparable to NiCd. Lithium titanate is charged to 2.80V and 1.80V at discharge. Figure 13 shows the properties of lithium titanate batteries. Typical uses are an electric drivetrain, UPS, and solar street lights. NCA enjoys the highest specific energy; however, lithium manganate and lithium iron phosphate provide superior specific power and thermal stability. Lithium titanate has the best service life.