Common six lithium battery characteristics and parameters

The specific parameters of the batteries of the same technical route are not exactly the same. The general level of the current parameters is shown in this paper. The six lithium batteries specifically include: lithium cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), lithium nickel cobalt manganese oxide (LiNiMnCoO2 or NMC), lithium cobalt aluminum aluminate (LiNiCoAlO2 or NCA), lithium iron phosphate (LiFePO4) and lithium titanate (Li4Ti5O12).

Cobalt acid lithium (LiCoO2)

Its high specific energy makes lithium cobalt oxide a popular choice for mobile phones, notebooks and digital cameras. The battery consists of a cobalt oxide cathode and a graphite carbon anode. The cathode has a layered structure in which lithium ions move from the anode to the cathode during discharge, and the charging process flows in the opposite direction.

The cathode has a layered structure. During discharge, lithium ions move from the anode to the cathode; during charging, the flow flows from the cathode to the anode.

Extremely, its cycle life is mainly limited by the solid electrolyte interface (SEI), mainly in the gradual thickening of the SEI film, and the anode plating problem of the fast charging or low temperature charging process. Newer material systems add nickel, manganese and/or aluminum to increase life, load capacity and reduce costs. Lithium cobaltate should not be charged and discharged at a higher current than the capacity. This means that an 18650 battery with 2,400mAh can only be charged and discharged at 2,400mA or less. Forcing rapid charging or applying a load higher than 2400mA can cause overheating and overload stress. For the best fast charging, the manufacturer recommends a charge rate of 0.8C or about 2,000mA. The battery protection circuit limits the charging and discharging rate of the energy unit to a safe level of about 1C. Hexagonal spider map (Figure 2) summarizes the specific energy or capacity aspects of lithium cobaltate performance associated with operation; specific power or ability to provide large currents; safety; performance in high and low temperature environments; lifetime including calendar life and cycle Life; cost characteristics. Other important features not shown in the spider map include toxicity, fast charging capability, self-discharge, and shelf life. Due to the high cost of cobalt and the significant performance improvements brought about by mixing materials with other active cathode materials, lithium cobalt oxide is being gradually replaced by lithium manganate, especially NMC and NCA.(please refer to the description in the face of the NMC and NCA.)

Cobalt acid lithium excels at high specific energy, but in power characteristics, safety and cycle life can provide general performance

Lithium manganese acid (LiMn2O4)

The spinel lithium manganate battery was first published in a 1983 material research report. In 1996, Moli Energy commercialized lithium-ion batteries with lithium manganate as the cathode material. The architecture forms a three-dimensional spinel structure that improves ion flow on the electrodes, reducing internal resistance and improving current carrying capacity. Another advantage of spinel is its high thermal stability and improved safety, but limited cycle and calendar life. Low battery internal resistance enables fast charging and high current discharge. 18650 type battery, lithium manganate battery can discharge at 20-30A, and has a moderate heat accumulation. It is also possible to apply a load pulse of up to 50A1 seconds. Continued high loads at this current can cause heat build-up and the battery temperature must not exceed 80 ° C (176 ° F). Lithium manganate is used in power tools, medical devices, and hybrid and pure electric vehicles. Figure 4 illustrates the formation of a three-dimensional crystal skeleton on the cathode of a lithium manganate battery. The spinel structure is usually composed of a diamond shape connected to a crystal lattice, which generally occurs after the battery is formed.

Manganese acid lithium cathode crystallization in into shape after three dimensional frame structure. Spinel provides low resistance, but the specific energy is lower than cobalt acid lithium.

Lithium manganese acid has a capacity of about a third lower than the cobalt acid lithium. Design flexibility allows engineers to choose utmost ground prolongs the service life of the battery, or upgrade the capacity of the maximum load current (power), or (more than).For example, 18650 long life of the battery version only moderate 1100mAh capacity; High capacity version 1500mAh. These feature parameters doesn't seem ideal, but the new design in power, security, and life has improved. Lithium manganate batteries are no longer common today; they are only used in special cases.

Despite the overall performance, a new design can improve the manganese acid lithium power, security, and longevity.

Most lithium manganate is mixed with lithium nickel manganese cobalt oxide (NMC) to increase specific energy and extend life. This combination brings the best performance of each system, and most electric vehicles, such as the Nissan Leaf, the Chevrolet Volt and the BMW i3, use LMO (NMC). The LMO part of the battery can reach about 30%, which can provide higher current during acceleration; the NMC part provides a long cruising range. Lithium ion battery research tends to combine lithium manganate with cobalt, nickel, manganese and/or aluminum as the active cathode material. In some architecture, 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, which is often closely tied to short cycle life. These three active metals and silicon reinforcement can be conveniently selected to increase specific energy (capacity), specific power (load capacity) or lifetime. Consumer batteries require large capacity, while industrial applications require battery systems, have good load capacity, long life, and provide safe and reliable service.

Nickel cobalt manganese acid lithium (LiNiMnCoO2 or NMC)

One of the most successful lithium ion systems is the cathode combination of nickel manganese cobalt (NMC). Similar to lithium manganate, this system can be customized for use as an energy battery or a power battery. For example, an NMC in an 18650 battery under medium load conditions has a capacity of approximately 2,800mAh and can provide a 4A to 5A discharge current; the same type of NMC is optimized for a specific power with a capacity of only 2,000mAh, but is available 20A continuous discharge current. The silicon-based anode will reach 4000mAh or more, but the load capacity is reduced and the cycle life is shortened. The silicon added to the graphite has a defect that the anode expands and contracts with charging and discharging, so that the mechanical stress of the battery is largely unstable. The secret of NMC lies in the combination of nickel and manganese. Similar to this is the salt, in which the main components sodium and chloride are themselves toxic, but they are mixed as a seasoning salt and a food preservative. Nickel is known for its high specific energy, but its stability is poor; the manganese spinel structure can achieve low internal resistance but low specific energy. The two active metals have complementary advantages.

The NMC is the battery of choice for power tools, electric bikes and other electric power systems. The cathode combination is typically one-third nickel, one-third manganese and one-third cobalt, also known as 1-1-1. This provides a unique blend that also reduces raw material costs due to reduced cobalt content. Another successful combination is NCM, which contains 5 parts nickel, 3 parts cobalt and 2 parts manganese (5-3-2). Other different amounts of cathode material combinations can also be used. Due to the high cost of cobalt, battery manufacturers have switched from cobalt to nickel cathodes. Nickel-based systems have higher energy density, lower cost, and longer cycle life than cobalt-based batteries, but their voltages are slightly lower. New electrolytes and additives can charge a single battery to more than 4.4V, increasing power.

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