Quick Understanding of Characteristics and Parameters of Six Common Lithium Batteries (4/6)
March 11, 2019
Lithium nickel cobalt manganate (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 energy or power batteries. For example, the NMC of 18650 batteries under moderate load has a capacity of about 2,800 mAh and can provide discharge current of 4A to 5A; while the same type of NMC can provide continuous discharge current of 20A while optimizing for specific power, its capacity is only 2,000 mAh. Silicon-based anodes will reach more than 4000 mAh, but their load capacity will be reduced and their cycle life will be shortened. Silicon added to graphite has defects, that is, the anode expands and shrinks with charging and discharging, which makes the mechanical stress structure of the battery unstable.
The secret of NMC is the combination of nickel and manganese. Similarly, salt, the main components of which are sodium and chloride themselves, is toxic, but they are mixed as seasoning salts and food preservatives. Nickel is famous for its high specific energy, but its stability is poor. Manganese spinel structure can achieve low internal resistance but low specific energy. The two active metals complement each other.
NMC is the preferred battery for power tools, electric bicycles and other electric power systems. The cathode assembly is usually one third nickel, one third manganese and one third cobalt, also known as 1-1-1. This provides a unique mixture that reduces the cost of raw materials due to a reduction in cobalt content. Another successful combination is NCM, which contains five copies of nickel, three copies of cobalt and two copies of manganese (5-3-2). Other combinations of different cathode materials can also be used.
Because of the high cost of cobalt, battery manufacturers have shifted 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, thus increasing the power consumption. Figure 7 shows the characteristics of NMC.
NMC has good overall performance and excellent performance in specific energy. This battery is the preferred choice for electric vehicles, with the lowest self-heating rate.
Due to the good economic and comprehensive performance of the system, more and more attention has been paid to NMC hybrid lithium-ion batteries. Three active materials, nickel, manganese and cobalt, can be easily mixed to adapt to the wide application of automotive and energy storage systems (EES) requiring frequent recycling. The diversity of the NMC family is growing.
breviation: NMC (NCM, CMN, CNM, MNC, MCN similar to different metal combinations) began in 2008.
typical battery operating range 3.0-4.2V or higher
Specific energy (capacity) 150-220 Wh/kg
Charging (C rate) 0.7-1C, charging to 4.20V, some to 4.30V; 3 hours typical charging. Charging current above 1C will shorten battery life.
Discharge (C rate) 1C; 2C may be feasible on some cores; 2.50V cut-off
Cycle Life 1000-2000 (Dependent on Discharge Depth and Temperature)
Thermal runaway is typical 210 degree C (410 degree F). High charge promotes thermal runaway
Electric Bicycles, Medical Equipment, Electric Vehicles, Industry
Annotations provide high capacity and high power. Mixed core. Welcomed by many uses, the market share is increasing.