NMC (nickel manganese cobalt)

NMC cathodes combine nickel, manganese and cobalt to deliver high energy density and good power. They are widely used in EVs but are generally more sensitive to high SOC and temperature than LFP, especially in nickel-rich variants.

What NMC offers

NMC is a family of layered oxide cathodes in which the ratio of nickel, manganese and cobalt varies. More nickel generally means higher energy density and less cobalt, at the cost of reduced stability. The result is a lighter pack, or more range for a given size, compared with LFP. NMC cells also often cope better with cold conditions than LFP and support high charging power in many vehicles, although the actual charging speed is set by the vehicle's design and BMS.

How NMC ages

Calendar and cycle studies on NMC cells show a clear dependence on SOC, temperature and the SOC window used for cycling. Holistic models built on such studies describe calendar loss as rising with temperature and SOC, and cycle loss as depending on depth of discharge and average SOC. Cycling in the middle of the SOC range was found to be gentler than cycling near the extremes.

Storage experiments also show that the SOC dependence comes in steps linked to the graphite anode, so some SOC ranges carry noticeably higher calendar stress than others. Comparative testing found NMC cells to have a shorter cycle life than LFP under similar conditions.

Nickel-rich cathodes and high SOC

In nickel-rich NMC, research has found that at high SOC the cathode surface can release oxygen and undergo structural changes, effects that intensify with temperature. This adds a cathode-side reason, on top of anode-side SEI growth, to limit the time spent at high SOC, especially in warm conditions.

This does not make an occasional full charge harmful in itself. The relevant factor is cumulative time at high SOC combined with temperature.

How Voltgevity models NMC

Voltgevity applies NMC-specific calendar and cycle parameters with a stronger SOC and temperature dependence than for LFP. Since NMC formulations differ between suppliers and generations, and lab cells differ from vehicle packs, the predictions include an uncertainty range.

Key takeaways

NMC offers high energy density and good cold-weather behaviour, with higher nickel content trading stability for energy.
Calendar ageing in NMC depends strongly on SOC and temperature, in steps linked to the anode.
Nickel-rich NMC adds cathode-side stress at high SOC, especially when warm.
Limiting time at high SOC, rather than avoiding 100 % entirely, is the main lever.