We often talk about ternary lithium batteries or iron-lithium batteries, which are named after the positive electrode active material. This article summarizes six common lithium battery types and their main performance parameters. As we all know, the specific parameters of batteries with the same technical route are not exactly the same. What this article shows is the general level of the current parameters. The six lithium batteries include: lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel cobalt manganese oxide (LiNiMnCoO2 or NMC), lithium nickel cobalt aluminate (LiNiCoAlO2 or NCA), lithium iron phosphate (LiFePO4) , lithium titanate
　　(Li4Ti5O12).
　　Let's all come together with Dongguan Yunsheng Electronics to learn about the characteristics and parameter comparison of six common lithium batteries.
　　1: Lithium cobalt oxide (LiCoO 2 )
　　has a high specific energy that makes lithium cobalt oxide the best choice for mobile phones, notebook computers and digital cameras. Popular choice. The battery consists of a cobalt oxide cathode and a graphitic carbon anode. The cathode has a layered structure, and lithium ions move from the anode to the cathode during discharge and in the opposite direction during charge. The structural form is shown in the figure below.
　　The cathode has a layered structure. During discharge, lithium ions move from the anode to the cathode; during charge the flow flows from the cathode to the anode.
　　The disadvantages of lithium cobalt oxide are relatively short lifetime, 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), which is mainly manifested in the gradual thickening of the SEI film and the anode plating during fast charging or low-temperature charging. Lithium problem. Newer material systems add nickel, manganese and/or aluminum to improve life, load capacity and reduce cost.
　　Lithium cobalt oxide should not be charged and discharged with a current higher than the capacity. This means that an 18650 battery with 2,400mAh can only be charged and discharged at ≤ 2,400mA. Forced fast charging or applying a load higher than 2400mA can cause overheating and excessive stress. For optimal fast charging, the manufacturer recommends a charge rate of 0.8C or about 2,000mA. A battery protection circuit limits the charge and discharge rate of the energy cell to a safe level of about 1C.
　　The hexagonal spider diagram (Figure 2) summarizes the performance of lithium cobalt oxide in terms of specific energy or capacity related to operation; specific power or ability
　　to provide in high and low temperature environments; life including calendar life and Cycle life; cost
　　characteristics. Other important characteristics not shown in the spider diagram include toxicity, fast charging capability, self-discharge, and shelf life.
　　Due to the high cost of cobalt and the obvious performance improvement brought about by mixing materials with other active cathode materials, lithium cobalt oxide is gradually being replaced by lithium manganese oxide, especially NMC and NCA. (Please see the description of NMC and NCA below.)
　　Lithium cobaltate is excellent in terms of high specific energy, but it can only provide general performance in terms of power characteristics, safety and cycle life. Summary
　　Table
　　2: Lithium manganese oxide ( LiMn2O4)
　　spinel lithium manganese oxide battery was first published in a material research report in 1983. In 1996, Moli Energy Company commercialized lithium-ion batteries with lithium manganese oxide as the cathode material. The architecture forms a three-dimensional spinel structure that improves ion flow on the electrodes, resulting in lower internal resistance and improved current-carrying capability. Another advantage of spinel is high thermal stability and improved safety, but limited cycle and calendar life.
　　Low battery internal resistance enables fast charging and high current discharging. 18650 type batteries, lithium manganese oxide batteries can be discharged at a current of 20-30A, and have moderate heat accumulation. It is also possible to apply a load pulse of up to 50A1 sec. Sustained high loads at this current will cause heat to build up and the battery temperature must not exceed 80°C (176°F). Lithium manganese oxide is used in electric tools, medical equipment, and hybrid and pure electric vehicles.
　　Figure 4 illustrates the formation of a three-dimensional crystalline framework on the cathode of a lithium manganate battery. The spinel structure usually consists of rhombohedral
　　shapes connected into a lattice, which typically appear after the battery is formed.
　　The cathode crystallization of lithium manganate has a three-dimensional skeleton structure formed after chemical formation. Spinel offers low electrical resistance but has a lower specific energy than lithium cobalt oxide.
　　The capacity of lithium manganese oxide is about one-third lower than that of lithium cobalt oxide. Design flexibility allows engineers to choose to maximize battery
　　life, or increase the maximum load current (specific power) or capacity (specific energy). For example, the long-life version of the 18650 battery has only a modest capacity of 1,100mAh; the high-capacity version reaches 1,500mAh.
　　Figure 5 shows the spider diagram of a typical lithium manganese oxide battery. These characteristic parameters may seem less than ideal, but the new design has improved in terms of power, safety and longevity. Pure lithium manganate batteries are no longer common today; they are only used in special cases.
　　Although the overall performance is mediocre, the new lithium manganese oxide design can improve power, safety and longevity.
　　Most lithium manganese oxides are mixed with lithium nickel manganese cobalt oxide (NMC) to increase specific energy and extend life. This combination brings out the best performance from each system, and most electric vehicles such as Nissan Leaf, Chevrolet Volt and BMW i3 have chosen LMO (NMC). The LMO part of the battery can reach about 30%, which can provide a higher current during acceleration; the NMC part provides a long cruising range.
　　Li-ion battery research tends to combine lithium manganate with cobalt, nickel, manganese and/or aluminum as the active cathode material. In some architectures, a small amount of silicon is added to the anode. This provides a 25% capacity boost; however, silicon expands and contracts as it charges and discharges, causing mechanical stress, and capacity boosts are often tied to short cycle life. These three active metals, together with silicon enhancements, can be conveniently selected to enhance specific energy (capacity), specific power (loading capacity), or lifetime. Consumer batteries require high capacity, while industrial applications require battery systems that have good load capacity, long life, and provide safe and reliable service.
　　Summary Table
　　3: Lithium Nickel Cobalt Manganese Oxide (LiNiMnCoO 2 or NMC)
　　One of the most successful Li-ion systems is the cathode combination of nickel manganese cobalt (NMC). Similar to lithium manganese oxide, this system can be customized for use as an energy battery or a power battery. For example, an NMC in an 18650 battery under moderate load conditions has a capacity of about 2,800mAh and can deliver 4A to 5A of discharge current; the same type of NMC, when optimized for a specific power, has a capacity of only 2,000mAh but can deliver 20A continuous discharge current. Silicon-based anodes will reach more than 4000mAh, but the load capacity will be reduced and the cycle life will be shortened. The silicon added to graphite has the defect that the anode expands and contracts as it is charged and discharged, making the battery mechanically stressed and structurally unstable.
　　The secret of NMC lies in the combination of nickel and manganese. Similar to this is table salt, in which the main ingredients sodium and chloride are poisonous by themselves, but they are combined as seasoning salt and food preservative. Nickel is known for its high specific energy but poor stability; manganese spinel structure can achieve low internal resistance but low specific energy. The two active metals have complementary advantages.
　　NMC is the battery of choice for power tools, e-bikes and other electric powertrains. The cathode combination is usually 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 the reduced cobalt content.
　　Another successful combination is NCM, which contains 5 parts nickel, 3 parts cobalt and 2 parts manganese (5-3-2). Other combinations of cathode materials in varying amounts can also be used.
　　Due to the high cost of cobalt, battery manufacturers switched from cobalt-based to nickel cathodes. Nickel-based systems have higher energy density, lower cost and longer cycle life than cobalt-based batteries, but their voltage is slightly lower.
　　New electrolytes and additives allow a single battery to be charged above 4.4V, increasing capacity. Figure 7 shows the characteristics of NMC.
　　NMC has good overall properties and excels in terms of specific energy. This battery is the first choice for electric vehicles with the lowest self-heating rate
　　Due to the relatively good economic performance and comprehensive performance of the system, NMC hybrid lithium-ion batteries have received more and more attention. The three active materials, nickel, manganese and cobalt, can be easily blended to accommodate a wide range of applications in automotive and energy storage systems (EES) that require frequent cycling. The diversity of the NMC family is growing.
　　Summary Table
　　4: Lithium Iron Phosphate (LiFePO 4 )
　　In 1996, the University of Texas found that phosphate can be used as a cathode material for rechargeable lithium batteries. Lithium phosphate has good electrochemical performance and low electrical resistance. This is achieved by nanoscale phosphate cathode materials. The main advantages are high current rating and long cycle life; good thermal stability for enhanced safety and tolerance to abuse. Lithium phosphate is more resistant to full charge conditions and is less stressed than other Li-ion systems if kept at high voltage for extended periods of time. The downside is that the lower 3.2V battery nominal voltage makes the specific energy lower than cobalt-doped Li-ion batteries. For most batteries, low temperatures will reduce performance, and elevated storage temperatures will 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 equalization problems, although it can be compensated by choosing a high-quality battery or using an advanced battery management system, both of which increase the cost of the battery pack. Battery life is very sensitive to impurities in the manufacturing process and cannot withstand moisture doping. Due to the presence of moisture impurities, some batteries have a minimum life of only 50 cycles. Figure 9 summarizes the properties of lithium phosphate.
　　Lithium phosphate is often used instead of lead-acid starter batteries. Four batteries in series produce 12.80V, similar to six 2V lead-acid batteries in series. The vehicle charges the lead acid to 14.40V (2.40V/battery) and maintains a float charge. The purpose of the float charge is to maintain a full charge level and prevent sulfation of the lead-acid battery.
　　By connecting four lithium phosphate cells in series, each cell is at 3.60V, which is the correct full charge voltage. At this time, the charging should be disconnected, but the charging should continue while driving. Lithium phosphate tolerates some overcharging; however, since most vehicles maintain the voltage at 14.40V for extended periods of time during long journeys, it may increase the mechanical stress on the lithium phosphate battery. Time will tell how long lithium phosphate can withstand overcharging as a replacement for lead-acid batteries. Cold temperatures also degrade lithium-ion performance, potentially affecting crankability in extreme conditions.
　　Lithium phosphate has good safety and long life, moderate specific energy, and enhanced self-discharge capability.
　　Five: Lithium nickel cobalt aluminate (LiNiCoAlO2 or NCA)
　　Lithium nickel cobalt aluminate battery or NCA has been used since 1999. It has high specific energy, fairly good specific power and long service life which are similar to NMC. Less flattering are safety and cost. Figure 11 summarizes the six key characteristics. NCA is a further development of lithium nickel oxide; adding aluminum gives the battery better chemical stability.
　　High energy and power density and good service life make NCA a candidate for EV powertrain. High cost and marginal safety have negative effects.
　　Six: Lithium titanate (Li4Ti5O12)
　　Batteries with lithium titanate anodes have been known since the 1980s. Lithium titanate replaces graphite in a typical lithium-ion battery anode, 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, can be charged quickly, and provides a high discharge current of 10C. The cycle times are said to be higher than those of conventional Li-ion batteries. Lithium titanate is safe and has excellent low-temperature discharge characteristics, achieving 80% capacity at -30°C (-22°F).
　　LTO (usually Li4Ti5O12) has zero strain, no SEI film formation and no lithium plating phenomenon during fast charging and low-temperature charging, so it has better charge-discharge performance than conventional cobalt-doped Li-ion and graphite anodes. Thermal stability at high temperatures is also better than other Li-ion systems; however, the batteries are expensive. Low specific energy, only 65W h/kg, comparable to NiCd. Lithium titanate is charged to 2.80V and 1.80V at the end of discharge. Figure 13 shows the characteristics of a lithium titanate battery. Typical uses are electric
　　powertrains, UPS and solar street lights.
　　Lithium titanate excels in safety, low-temperature performance, and longevity. Efforts are being made to increase specific energy and reduce costs.
　　The figure below compares the specific energy of systems based on lead, nickel and lithium. While lithium-aluminum (NCA) is the clear winner by storing more capacity than other systems, it is only suitable for power usage in specific scenarios. Lithium manganese oxide
　　(LMO) and lithium phosphate (LFP) are excellent in terms of specific power and thermal stability. Lithium titanate (LTO) may have a lower capacity, but it outlasts most other batteries and has the best low-temperature performance.
　　Typical specific energy NCAs of lead, nickel, and lithium-based batteries
　　enjoy 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.