NCA (nickel cobalt aluminium)

NCA is a nickel-rich layered oxide cathode with aluminium as a stabiliser, offering high energy density. Its ageing behaviour resembles that of nickel-rich NMC, with clear sensitivity to time at high SOC and temperature.

Characteristics

NCA cathodes contain a high share of nickel with smaller amounts of cobalt and aluminium. This gives high energy density, which made NCA attractive for long-range vehicles. Like other nickel-rich cathodes, NCA trades some structural and thermal stability for that energy. NCA is less widespread in EVs than NMC or LFP, and its share has shifted over time as manufacturers have diversified their chemistries.

Calendar ageing and SOC

Storage studies that included NCA cells found a strong dependence of calendar ageing on SOC, with plateaus and steps linked to the potential stages of the graphite anode. In those experiments the higher SOC ranges were associated with markedly faster calendar ageing, and higher temperature amplified the effect.

Reviews of lithium-ion ageing describe the same main mechanisms here as in other graphite-based cells: SEI growth, lithium plating under unfavourable charging conditions, and cathode-side degradation. Research on nickel-rich cathodes adds surface reactions and structural changes at high SOC to that list.

Cycle life

Comparative testing of commercial cells found that NCA cells, like NMC cells, had a substantially shorter cycle life than LFP under similar conditions, and that they responded differently to depth of discharge, temperature and C-rate. In vehicle packs, buffers, thermal management and BMS strategy change how much of that lab behaviour shows up in practice.

Practical implications and Voltgevity's approach

For NCA vehicles, reducing time at high SOC, particularly in warm weather, is generally a meaningful battery-preserving alternative. Charging to a higher level shortly before a long trip adds little extra stress compared with leaving the car full for days.

Voltgevity groups NCA with the nickel-rich chemistries and applies a pronounced SOC and temperature dependence for calendar ageing. Because public NCA data covers specific cells and generations, the predictions carry an uncertainty range.

Key takeaways

NCA is a nickel-rich, high-energy cathode whose ageing resembles nickel-rich NMC.
Calendar ageing in NCA is sensitive to SOC and temperature, with steps linked to the anode.
Cycle life is generally shorter than LFP under comparable conditions.
Limiting time at high SOC, especially in heat, is the main lever; a full charge just before a trip adds little.