We often talk about ternary lithium batteries or lithium iron batteries, which are named according to the positive active materials. 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 types of lithium batteries specifically include: lithium cobalt oxide, lithium manganate, lithium nickel cobalt manganate (NCM), lithium nickel cobalt aluminate (NCA), lithium iron phosphate, and lithium titanate.

1. Lithium cobalt oxide (LiCoO2)

Its high specific energy makes lithium cobalt oxide a popular choice for cell phones, laptops and digital cameras. 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. 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 negative electrode plating during fast charging or low-temperature charging. Lithium issue. Newer material systems add nickel, manganese and/or aluminum to increase life, load capacity and reduce cost.

A hexagonal spider diagram summarizing LiCoO performance in terms of specific energy or capacity in relation to operation. Lithium cobalt oxide excels at high specific energy, but offers only mediocre performance in terms of power characteristics, safety and cycle life.

2. Lithium manganate (LiMn2O4)

Spinel lithium manganate batteries were first published in a 1983 materials research report. In 1996, Moli Energy Company commercialized lithium-ion batteries using lithium manganate as the cathode material. The architecture creates a three-dimensional spinel structure that improves ion flow across the electrodes, thereby lowering internal resistance and improving current-carrying capabilities. Another advantage of spinel is high thermal stability and improved safety, but limited cycle and calendar life.

Low internal battery resistance enables fast charging and high current discharge. 18650 type battery cell, lithium manganate battery can be discharged at a current of 20-30A and has moderate heat accumulation. The battery temperature cannot exceed 80°C. Lithium manganate is used in power tools, medical devices, and hybrid and pure electric vehicles. The capacity of lithium manganate is approximately one third lower than that of lithium cobalt oxide. Design flexibility gives engineers the option to maximize battery life or increase maximum load current or capacity.

Figure 3 shows a spider diagram of a typical lithium manganate battery. These performance parameters may seem less than ideal, but the new design offers improvements in power, safety and longevity. Pure lithium manganese oxide batteries are no longer common today; they are only used in special cases.

Figure 3 Spider diagram of pure lithium manganate battery 

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 from each system, and most electric vehicles such as the Nissan Leaf, Chevrolet Volt and BMW i3 use LMO (NMC). The LMO part of the battery can reach about 30% and 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 architectures, a small amount of silicon is added to the negative electrode. This provides a 25% capacity boost; however, silicon expands and contracts with charge and discharge, causing mechanical stress, and capacity improvements are often tied to short cycle life.

Table 4 Characteristics of lithium manganate oxide

3. Lithium Nickel Cobalt Manganese Oxide (NMC)

One of the most successful lithium-ion systems is the nickel-manganese-cobalt (NMC) cathode combination. Similar to lithium manganate, this system can be customized for use as an energy or power battery. For example, the NMC in an 18650 battery under medium load conditions has a capacity of about 2,800mAh and can deliver 4A to 5A 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. The silicon-based negative electrode 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 a defect, that is, the negative electrode expands and contracts with charging and discharging, 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, where the main ingredients, sodium and chloride, are toxic on their own, but are mixed together to act as seasoning salt and a food preservative. Nickel is known for its high specific energy but poor stability; the 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 positive electrode 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 reduced cobalt content. Another winning 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 may also be used.