NMC (LiNiₓMnᵧCo₁₋ₓ₋ᵧO₂): structure, nickel content and stability

NMC has the same layered structure as LiCoO₂: a hexagonal α-NaFeO₂-type lattice, space group R-3m (Hashem et al. 2019), with lithium on the 3a sites, transition metals on the 3b sites and oxygen on the 6c sites, so layers of LiO₆ octahedra alternate with layers of MO₆ octahedra (Liao et al. 2022). The difference is that the metal layer holds a mixture of nickel, manganese and cobalt instead of cobalt alone.

In NMC111 (LiNi₁/₃Mn₁/₃Co₁/₃O₂) nickel is Ni²⁺ and manganese Mn⁴⁺ (Hashem et al. 2019). Manganese oxidizes to Mn⁴⁺ during synthesis by reducing nickel to Ni²⁺, so Mn helps incorporate nickel stably and acts as a structural stabilizer without taking part in charge and discharge (Manthiram 2020). Because Ni²⁺ (0.69 Å) is almost the same size as Li⁺, some nickel ends up on lithium sites; this cation mixing blocks Li diffusion, and cobalt helps reduce it (Hashem et al. 2019; Liao et al. 2022).

The name gives the nickel:manganese:cobalt ratio: NMC111 has equal amounts (Hashem et al. 2019), NMC532 is LiNi₀.₅Mn₀.₃Co₀.₂O₂, NMC622 LiNi₀.₆Mn₀.₂Co₀.₂O₂ and NMC811 LiNi₀.₈Mn₀.₁Co₀.₁O₂ (from the naming convention; many papers write NCM, Liao et al. 2022). In practice the trend has been to raise nickel and cut cobalt: nickel can be cycled from Ni²⁺ to Ni⁴⁺ without losing much lattice oxygen, unlike cobalt, so more nickel gives more capacity at lower cost (Manthiram 2020).

Each metal brings something: cobalt has good structural stability but releases oxygen at high charge, manganese is chemically stable but tends to migrate into the lithium layer, and nickel lies in between (Manthiram 2020). The theoretical capacity barely changes with composition, about 278 mAh g⁻¹ for NMC111 and 276 mAh g⁻¹ for NMC811 (calculated from the molar masses); what nickel changes is how much of the lithium can be used within a practical voltage window.

Nickel-rich layered oxides suffer from cycle, thermal and air instability, all linked to highly oxidized nickel in contact with the liquid electrolyte or air (Manthiram 2020). The main mechanisms are:

• Microcracking. On deep charge NMC goes from H1 through a monoclinic phase to H2 and H3; in NMC811 the H2 → H3 transition above 4.11 V shrinks the c axis abruptly, and the more nickel, the larger the collapse. The anisotropic volume change cracks secondary particles apart along grain boundaries (Liao et al. 2022). In nickel-rich NCA the unit-cell volume drops by 5.63%, 7.10% and 8.37% at 80%, 88% and 95% Ni (Liao et al. 2022).
• Oxygen release. Lattice oxygen escapes at high states of charge and reacts with the electrolyte, releasing O₂ and CO₂; the gas release correlates with Ni content (Liao et al. 2022).
• Surface reconstruction. The surface turns from layered to spinel to a NiO-like rock-salt structure that blocks lithium (Liao et al. 2022). In LiNiₓMnₓCo₁₋₂ₓO₂ this reconstruction runs mainly along the lithium diffusion channels, and the surface reaction layer is LiF in an organic matrix; together they cause much of the capacity fading and impedance rise at high voltage (Lin et al. 2014). After cycling, the rock-salt layer was at most 3 nm thick on NCM622 at 4.5 V but about 5 nm on a 90% Ni cathode already at 4.3 V (Liao et al. 2022).
• Metal dissolution. Ni and Mn dissolve, migrate to the graphite anode and thicken its SEI, more so the higher the Ni content (Manthiram 2020).

Single crystals. Conventional NMC is made of polycrystalline secondary particles; their randomly oriented primary grains build up stress at grain boundaries and crack apart. Single-crystal particles avoid intergranular cracks, show phase change to rock salt only at the surface and cycle better, especially at high voltage, and they release less gas (Liao et al. 2022). Their limits are slower Li diffusion through large particles (Fan et al. 2021) and gliding of the layers inside the crystal, which is largely reversible but can create cracks near the surface; keeping crystals below about 3.5 µm helps (Liao et al. 2022). In single-crystal NCM with 65% Ni, capacity loss tracked the thickness of a rock-salt NiO-type surface layer rather than cracking (Zhao et al. 2023).

Coatings. Oxides such as Al₂O₃, ZrO₂ and TiO₂, fluorides, phosphates, conductive polymers and fast Li-ion conductors are coated on the particles to block side reactions with the electrolyte and HF (Liao et al. 2022).

Doping. Small amounts of Mg, Al, Ti, Zr, B and others stabilize the lattice; 2 mol% Mg on lithium sites acts as a pillar that reduces anisotropic strain and microcracking (Liao et al. 2022), and Al or Mg doping improved the cycling of NMC111 (Hashem et al. 2019). Al doping also strengthens metal–oxygen bonds and suppresses dissolution in nickel-rich cathodes (Manthiram 2020). Concentration gradients across the particles are another strategy (Lu et al. 2024; Wang et al. 2025).

Nickel-rich NMC cathodes, with their high capacity, are the principal candidates for long-range electric vehicles (Liao et al. 2022), and millions of electric vehicles run on nickel-rich layered oxide cathodes (Lu et al. 2024). Alongside NCA, LiMn₂O₄ and LiFePO₄, NCM is used in electric vehicles and stationary storage, while LiCoO₂ stays in portable electronics (Lin et al. 2026). For the place of NMC among cathodes, anodes and electrolytes, see battery materials.

Draw NMC as you would LiCoO₂, side on so the alternating layers show, but colour the metal layer with three kinds of octahedra, nickel, manganese and cobalt, in the right ratio: for NMC811, eight Ni to every Mn and Co. To explain degradation, add a cracked secondary particle and a thin rock-salt shell on the surface. The LabCanvas figure editor’s Library has battery crystal objects, including a layered oxide and NMC811, that drop into a figure as high-resolution vector drawings you can recolour and label. The LabCanvas 3D Studio has battery models you can rotate, show as polyhedra and export as high-resolution images.