1. What a cathode material is (the short version)

The cathode is “the crystal that gives up lithium on charge and takes it back on discharge”. The perspective by Li and co-authors in Nature Energy says the cathode is normally the largest component by both weight and cost in state-of-the-art lithium-ion cells and is still a main bottleneck for energy densitySourced. The IEA puts the cathode active material at 40 to 50% of cell production cost for NMC batteries and 25 to 30% for LFP batteriesSourced.

• Three families: according to Manthiram's review, the oxide cathodes in use fall into layered oxides, spinel oxides and polyanion oxides, all of which originate from Goodenough's groupsSourced. The 2020 review calls these the only practical classes
• Two aims: to raise capacity (more lithium extracted, more nickel, higher voltage), and to reduce expensive, unevenly distributed elements such as cobaltSourced
• The core difficulty: the more lithium is pulled out, the higher the capacity, but the less stable the crystal. Li and co-authors summarise that whatever the composition, large lithium utilisation brings singlet oxygen evolution, transition-metal dissolution, rock-salt phase formation and anisotropic lattice distortion (particle cracking)Sourced

2. Three structural families — layered, spinel, polyanion

Manthiram's review explains the three families through crystal structure, how lithium moves and how voltage is setSourced.

View the original SVG schematic and exact annotations

All Sourced (statements in each reference). Voltages and capacities are values under different conditions placed side by side, not a ranking. Layered and polyanion families are also the basis of sodium-ion battery cathodes [Reference 1].

On the market side, the IEA's Global EV Outlook 2026 (published 20 May 2026) says that LFP accounted for over 55% of EV batteries deployed globally in 2025, up from nearly 50% in 2024 [Reference 3]Sourced. LFP use is concentrated in China and in emerging economies, and among the EV battery chemistries deployed outside China in 2025, almost 80% used nickel-containing chemistries such as NMCSourced. In other words, nickel-based layered oxides and polyanion LFP are used side by side, split by use and region.

3. Our calculation: the gap between theoretical and practical capacity

A cathode's capacity is set by how much of the lithium in the crystal can actually be moved in and out. Theoretical capacity comes from dividing the Faraday constant (96,485 C/mol = 26,801 mAh/mol) by the molar mass of the active material per lithium. Comparing with reported practical capacities gives the lithium utilisation.

Practical capacities are Sourced (each reference); theoretical capacities and utilisation are Our calculation. The practical capacities are material values such as half-cell results and their conditions are not uniform. The LFP value is from the 1997 first report, not from later improved products.

4. A materials engineer's view (1): “lithium utilisation” trades capacity against life

5. High nickel, high voltage, cobalt-free — three directions

The perspective by Li and co-authors estimates that to reach a cell-level specific energy of 350 Wh/kg or more, at least 800 Wh/kg is needed from the cathode active material (for state-of-the-art designs, without a lithium-metal anode)Sourced. That 800 Wh/kg corresponds to about 210 to 215 mAh/g at 3.7 to 3.8 V (vs Li). There are three main roads toward it.

(1) Increase nickel

At 4.3 V (vs Li), about 200 mAh/g can be reversibly accessed from NMC811 and NCA80, against about 160 mAh/g from NMC111Sourced. Over the last decade, energy gains in automotive NMC came mainly from raising nickel content: NMC111 → 523 → 622 → 811. NCA, which started with high nickel, saw only a modest increase from about 250 Wh/kg (cell) in 2009, the perspective notesSourced.

(2) Raise the voltage

Instead of more nickel, this road raises the upper voltage to increase lithium utilisation. Li and co-authors say this “ultrahigh voltage” route brings marginal advantages in thermal-abuse tolerance, but faces electrolyte compatibility issues and cobalt supply riskSourced. The high-voltage spinel LNMO offers about 4.7 V and about 135 mAh/g with high power, but its capacity fades badly in full cells with a graphite anode, particularly at elevated temperature, which has hindered commercialisation. The causes given are metal dissolution at 4.7 V and lithium consumption by an SEI that grows faster when Mn and Ni deposit on graphiteSourced.

(3) Reduce or eliminate cobalt

Li and co-authors summarise the roles of Co, Mn and Al in nickel-based layered oxides as followsSourced.

All Sourced (the perspective by Li and co-authors [Reference 2]). Manthiram's review [Reference 1] likewise treats Mn⁴⁺ as a structural stabiliser and Co as structurally stable but the origin of oxygen release.

On cobalt use, the same perspective states that state-of-the-art NCM uses 80 to 200 g of Co and 500 to 650 g of Ni per kWh, that NCM-811 uses 80 to 100 g Co/kWh, and that Panasonic's state-of-the-art NCA with under 50 g Co per kWh was deployed in Tesla Model 3 batteries (as of 2019)Sourced. It also notes that experts at cathode and cell makers do not agree on whether high-nickel, low-cobalt NCM is more competitive than NCASourced.

As an example of a cobalt-free high-nickel material, Li, Lee and Manthiram reported NMA (LiNi_1−x−yMn_xAl_yO2) in Advanced Materials [Reference 13]. NMA with 89 mol% Ni had a slightly lower specific capacity than NMC and NCA of identical Ni content but operated at about 40 mV higher voltage, showed no compromise in rate capability, and in pouch cells with graphite outperformed NMC and NCA after 1,000 deep cycles (conditions of that study)Sourced. It only slightly trailed an Al–Mg co-doped NMC and a commercial cathode. Its thermal stability was also reported to be superiorSourced. The perspective by Li and co-authors also offers the view that strictly cobalt-free compositions may not be necessary from purely economic or geopolitical standpoints, and that there is a marketing element as wellSourced.

6. Our calculation: cobalt per kWh

To see what “reducing cobalt” means, we convert composition and capacity into the amount of cobalt needed to make 1 kWh of cell.

7. Four degradation pathways

We organise the degradation that occurs at high lithium utilisation into four pathways, based on primary sources (the grouping into four is this article's own).

View the original SVG schematic and exact annotations

Degradation in batteries using high-nickel cathodes spans the cathode, the anode and the electrolyte. The review by Jiang and co-authors sets out each degradation process and the stabilisation strategies [Reference 19].

Pathway 1: particle cracking

A standard cathode is spherical polycrystalline secondary particles made by co-precipitation, with hundreds of primary particles densely packedSourced. On cycling, the lattice stretches and shrinks by different amounts along different directions (anisotropic lattice distortion), and in high-nickel materials multistep two-phase reactions add to this, so cracks form. Cracks expose new surface, promoting reaction with the electrolyte, metal dissolution and SEI growth, and speeding capacity loss. This is said to become especially pronounced beyond about 500 cyclesSourced. Yan and co-authors, using scanning transmission electron microscopy on a commercial NMC111, observed that cracks form inside grains (not from grain boundaries or surfaces) and are directly tied to high-voltage cycling, and showed a dislocation-based crack incubation mechanismSourced.

Pathway 2: surface rock-salt formation

Lin and co-authors write that in LiNi_1−x−yMn_xCo_yO2, surface reconstruction from a layered to a rock-salt structure is commonly observed under a variety of operating conditions, particularly in Ni-rich compositions, and contributes to poor high-voltage cyclingSourced. The same paper reports that hierarchically structured LiNi0.4Mn0.4Co0.2O2 particles made by spray pyrolysis, whose surfaces are Ni-poor and Mn-rich, resisted surface reconstruction better and showed improved high-voltage cyclingSourced.

Pathway 3: oxygen release

The review by Sharifi-Asl and co-authors states that oxygen release from oxygen-containing positive electrode materials is one of the major structural degradations, causing rapid capacity and voltage fading and triggering parasitic thermal runaway events, and treats layered, spinel, olivine and Li-rich cathodes in turnSourced. Jung and co-authors say that the CO2 and CO long attributed to electrolyte oxidation in NMC are, they believe, mainly due to chemical reaction of reactive lattice oxygen with the electrolyte, and observed capacity fading tied to the high-voltage phase transition (H2 to H3) in NMC811Sourced. Thermal runaway itself is covered in the “Thermal Runaway and Battery Safety” article in this series.

Pathway 4: transition-metal dissolution

Zhan and co-authors showed, for spinel LiMn2O4 and carbon cells, that the manganese deposited on the anode is in the +2 state, deposited by a metathesis reaction with species in the SEI rather than by reduction to metallic Mn, and that the amount deposited rises with cycling and correlates well with rising anode impedance and capacity fadeSourced. For high nickel, Manthiram writes that Ni⁴⁺ reacts aggressively with the electrolyte to form thick SEI layers and dissolved Ni and Mn deposit on graphite, catalyse electrolyte decomposition and thicken the SEI furtherSourced. Doping with a small amount of Al is described as suppressing metal dissolution and improving long-term cycle lifeSourced.

In addition, for high nickel, surface residual lithium compounds are described as causing storage problems and gas evolution from reactions with the electrolyte, and air stability is also a challengeSourced.

8. A materials engineer's view (2): cracking, oxygen and dissolution are linked

9. Particle design — polycrystalline, single-crystal, gradient, coated

Even with the same composition, how the particle is made changes its character. Li and co-authors say particle morphology, microstructure and surface properties are central to the energy output of a cathodeSourced.

View the original SVG schematic and exact annotations

(1) Standard: polycrystalline secondary particles

High-nickel NCM and NCA electrodes reach about 3.0 to 3.4 g/cm³, against 3.8 to 4.2 g/cm³ for LCO, so they beat LCO in specific energy (Wh/kg) but not in energy density per volume (Wh/L). Pushing electrode density higher (about 3.4 g/cm³ or more) is said to severely compromise rate capability and lifetime through higher impedance, particle pulverisation and electrode delaminationSourced. Tuning the primary particles (nanosizing, realignment, grain-boundary reinforcement) is tried to aid lithium transport, ease strain and raise the mechanical strength of the secondary particleSourced.

(2) Single-crystal

Micron-scale single-crystal particles are mechanically more robust than polycrystalline particles during electrode pressing and battery operation, though with inferior specific capacity and rate capability. The better stability could allow a higher charging voltage (for example 4.5 V vs Li or more) to make up for the capacity, provided compatible electrolytes are developedSourced. The most economical synthesis is described as calcining precipitated precursors of smaller average size (3 to 5 µm, against 10 µm or more as the industrial norm) at high temperature (950°C or more) and/or with a flux, but tuned co-precipitation and calcination lower throughput and raise costSourced. Ge and co-authors examined single-crystal LiNi0.8Mn0.1Co0.1O2 with operando X-ray microscopy and spectroscopy and found sluggish redox at low state of charge, governed by ionic transport, which may be alleviated by combining with polycrystals in the same electrodeSourced.

(3) Concentration gradient

Sun and co-authors reported a cathode in which the particle centre is rich in Ni, and moving outward Ni falls while Mn and Co rise. A half cell gave 209 mAh/g and retained 96% after 50 cycles under an aggressive test (55°C, 3.0 to 4.4 V), and it also did better in thermal-abuse tests than the reference Li[Ni0.8Co0.1Mn0.1]O2Sourced. In another paper, a “full-gradient” material in which Ni falls linearly and Mn rises linearly gave 215 mAh/g, with secondary particles made of aligned needle-like nanosize primary particlesSourced. Li and co-authors, however, say concentration-gradient NCM had not registered a notable market share in the automotive cathode landscape, citing the cost and consistency concerns of a more complicated co-precipitation, the fact that the Ni-rich core and Mn-rich surface need different calcination temperatures, and a possible need for surface passivation against Mn dissolution (as of 2019)Sourced.

(4) Surface and grain-boundary stabilisation

As-synthesised high-nickel powder is routinely surface-treated for stability during electrode fabrication and cell operation. Li and co-authors describe dry or water-based coating as the most economical for industry; water-based coating washes off surface Li residues directly but exposure to water promotes surface rock-salt formation (Li leaching) and lowers capacity and cyclability; wet coating in organic solvents avoids this and gives good uniformity but at extra cost for fire hazards and waste disposal; and CVD and ALD give the best uniformity but must fall further in priceSourced. Coatings can cover the secondary particles only or penetrate to coat primary particles, and passivation at the primary-particle level can be more effective at suppressing gas generation and mechanical fractureSourced. Dopants such as Mg, Zr and Ti are routinely introduced into commercial high-nickel oxides for tuning, but optimal amounts are very small (sometimes ppm level), and large amounts cause structural defects and impurities that degrade propertiesSourced.

10. Synthesis — co-precipitation and calcination

The Argonne National Laboratory technoeconomic model (Journal of Power Sources, 2026) sets out an industrial synthesis of NMC step by step. These are the model's assumptions, not the actual conditions of any manufacturerSourced.

In the model, the precursor is made from sulfates by co-precipitation (nitrogen atmosphere, 95°C, pH 11 to 11.5), mixed with lithium hydroxide monohydrate and calcined in an oxygen atmosphere. After calcination the material is deagglomerated, milled and sized, washed while a coating material is mixed in, dried and calcined a second timeSourced. The calcination conditions assumed in the Argonne model are as follows (values from its Table 7).

All Sourced (the assumptions of the Argonne National Laboratory technoeconomic model; also a heating ramp of 2.8°C/min, a cooling ramp of 4.0°C/min and saggar loads of 10 kg for polycrystalline and 5 kg for single-crystal) [Reference 12]. These are not actual manufacturing conditions.

11. Where LFP, LMFP and spinel stand

• LFP: in 1997 Padhi and co-authors reported reversible lithium extraction and insertion in LiFePO4 (triphylite) at 3.5 V vs lithium, with a specific capacity then of 100 to 110 mAh/g, and called it a candidate for the cathode of a low-power rechargeable lithium batterySourced (at 0.05 mA/cm²). Manthiram's review says polyanion cathodes need small particles coated with conductive carbon, which often increases processing cost and introduces inconsistencies in performanceSourced. The IEA says LFP was over 55% of EV batteries in 2025 [Reference 3]Sourced
• LMFP: LiMn_1−xFe_xPO4, with part of the iron replaced by manganese. The review by Sun and co-authors explains that Fe and Mn were combined in a certain ratio to compensate for LFP's slow electron and Li⁺ transportSourced [Reference 17]. Xiao and co-authors reported LMFP/C of about 60 nm particles with a 1 to 2 nm carbon coating (1.8 wt% carbon), in which LiMn_0.75Fe_0.25PO4/C gave the highest energy and power at low rates and LiMn_0.5Fe_0.5PO4/C may be the ideal option for practical large-scale applications; the Mn-rich composition (x = 0.25) delivered 157 mAh/g at 0.1CSourced [Reference 16]. IEA statistics include LMFP within the LFP categorySourced. Performance values of current mass-produced LMFP cells could not be confirmed in primary sources
• LMO: the review by Huang and co-authors calls LiMn2O4 cheap and environmentally friendly, with excellent rate performance from 3D Li⁺ diffusion channels, but says it degrades severely under extreme voltages and at high temperature. It distinguishes “good spinel” surface phases (such as LiNi0.5Mn1.5O4) from “bad spinel” ones (Mn3O4)Sourced [Reference 15]
• LNMO: high power at about 4.7 V and about 135 mAh/g, but heavy capacity fade in full cells with graphite has hindered commercialisation (section 5)Sourced [Reference 14]

12. Strengths and weaknesses; how this article divides work with others in the series

What this article does not cover

• Resources, sourcing and price: the resources and supply of cobalt, nickel, lithium and phosphorus are left to the “Battery Raw Materials and Supply Chains” article. The Co quantities here are conversions from composition and capacity, not a supply discussion
• Other components: graphite anodes (“Graphite Anodes and Electrode Design”), conductive additives and binders (the article of that name), electrolytes and separators (the article of that name), the SEI (“SEI”), electrode manufacturing (“Electrode Manufacturing”)
• All-solid-state batteries: cathodes for all-solid-state batteries (such as oxide coatings) are covered in a separate field, in articles such as the all-solid-state battery article on interfacial resistance
• What could not be confirmed: the latest product compositions, particle specifications and production volumes of individual companies; the current market share of single-crystal and gradient materials (the statements by Li and co-authors date from 2019); performance values of current mass-produced LMFP cells; and the commercial status of cathodes under development such as Li-rich and disordered rock-salt types. None of these is filled in by guesswork

13. How to read evaluations and standards

Before comparing which number is larger, align the basis of comparison in the following order. This is an editorial reading checklist, not a set of test conditions or acceptance limits prescribed by a standard.

1. What was measured?

reversible capacity, average voltage, retention and thermal behaviour. Check the units and whether the result describes a material, component or complete system.

2. Under which conditions?

composition, upper cutoff voltage, electrode density, particle structure, temperature and electrolyte. Treat results under different conditions as separate results before comparing them.

3. The comparison trap

Material mAh/g alone does not determine cell Wh/kg or safety.

4. What does the standard cover?

Check the identifier, title, edition and scope in the issuing body’s material. Distinguish test methods, safety, interoperability and management requirements. Naming a standard alone does not establish that a test, conformity assessment or certification has been completed.

Keep a comparison note containing the object, units, conditions, sample count and variation, comparator, standard edition and unresolved points. Do not invent numerical conditions or acceptance limits from a public abstract of a standard.

14. Glossary

15. References (primary sources)

1. Manthiram "A reflection on lithium-ion battery cathode chemistry," Nature Communications 11, 1550 (2020) — doi.org/10.1038/s41467-020-15355-0
2. Li, Erickson, Manthiram "High-nickel layered oxide cathodes for lithium-based automotive batteries," Nature Energy 5, 26–34 (2020) (text checked in the author manuscript posted on the U.S. Department of Energy's OSTI) — doi.org/10.1038/s41560-019-0513-0
3. International Energy Agency (IEA) "Global EV Outlook 2026," chapter "Electric vehicle batteries," published 20 May 2026 — iea.org
4. Padhi, Nanjundaswamy, Goodenough "Phospho-olivines as Positive-Electrode Materials for Rechargeable Lithium Batteries," Journal of The Electrochemical Society 144, 1188–1194 (1997) — doi.org/10.1149/1.1837571
5. Jung et al. "Oxygen Release and Its Effect on the Cycling Stability of LiNixMnyCozO2 (NMC) Cathode Materials for Li-Ion Batteries," Journal of The Electrochemical Society 164, A1361–A1377 (2017) — doi.org/10.1149/2.0021707jes
6. Sharifi-Asl, Lu, Amine, Shahbazian-Yassar "Oxygen Release Degradation in Li-Ion Battery Cathode Materials: Mechanisms and Mitigating Approaches," Advanced Energy Materials 9, 1900551 (2019) — doi.org/10.1002/aenm.201900551
7. Yan et al. "Intragranular cracking as a critical barrier for high-voltage usage of layer-structured cathode for lithium-ion batteries," Nature Communications 8, 14101 (2017) — doi.org/10.1038/ncomms14101
8. Zhan et al. "Mn(II) deposition on anodes and its effects on capacity fade in spinel lithium manganate–carbon systems," Nature Communications 4, 2437 (2013) — doi.org/10.1038/ncomms3437
9. Lin et al. "Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries," Nature Energy 1, 15004 (2016) — doi.org/10.1038/nenergy.2015.4
10. Sun, Myung, Park, Prakash, Belharouak, Amine "High-energy cathode material for long-life and safe lithium batteries," Nature Materials 8, 320–324 (2009) — doi.org/10.1038/nmat2418
11. Sun et al. "Nanostructured high-energy cathode materials for advanced lithium batteries," Nature Materials 11, 942–947 (2012) — doi.org/10.1038/nmat3435
12. Knehr, Effat, Kubal, Su, Neu, Chacko, Gordon, Ahmed (Argonne National Laboratory and others) "A technoeconomic analysis of poly- and single-crystalline NMCxyz from material synthesis to battery pack design," Journal of Power Sources 677, 240032 (2026) (text checked in the OSTI version) — doi.org/10.1016/j.jpowsour.2026.240032
13. Li, Lee, Manthiram "High-Nickel NMA: A Cobalt-Free Alternative to NMC and NCA Cathodes for Lithium-Ion Batteries," Advanced Materials 32, 2002718 (2020) — doi.org/10.1002/adma.202002718
14. Manthiram, Chemelewski, Lee "A perspective on the high-voltage LiMn1.5Ni0.5O4 spinel cathode for lithium-ion batteries," Energy & Environmental Science 7, 1339 (2014) — doi.org/10.1039/c3ee42981d
15. Huang, Dong, Li, Lee "Lithium Manganese Spinel Cathodes for Lithium-Ion Batteries," Advanced Energy Materials 11, 2000997 (2021) — doi.org/10.1002/aenm.202000997
16. Xiao, Ding, Lai, Lu "High Performance LiMn1−xFexPO4 (0 ≤ x ≤ 1) Synthesized via a Facile Polymer-Assisted Mechanical Activation," Journal of The Electrochemical Society 160, A918–A926 (2013) — doi.org/10.1149/2.116306jes
17. Sun, Luo, Du, Wei "Research progress of lithium manganese iron phosphate cathode materials: From preparation to modification," Electroanalysis 36, e202400120 (2024) — doi.org/10.1002/elan.202400120
18. Ge, Wi, Liu, Bai et al. "Kinetic Limitations in Single-Crystal High-Nickel Cathodes," Angewandte Chemie International Edition 60, 17350–17355 (2021) — doi.org/10.1002/anie.202012773
19. Jiang, Danilov, Eichel, Notten "A Review of Degradation Mechanisms and Recent Achievements for Ni-Rich Cathode-Based Li-Ion Batteries," Advanced Energy Materials 11, 2103005 (2021) — doi.org/10.1002/aenm.202103005

16. Claim-to-source audit

Last updated 10 October 2026. Sources are limited to primary material (abstracts and bibliographic records of peer-reviewed papers, the full text of open-access reviews and perspectives, an Argonne National Laboratory technoeconomic analysis and IEA reports). Because the article includes structural readings and materials-design interpretations, those are marked as Commentary and kept separate from sourced fact. The latest product compositions, particle specifications and production volumes of individual companies, the current market share of single-crystal and gradient materials, and performance values of current mass-produced LMFP cells are not stated here because no published primary source could be confirmed. Paper values are from abstracts or reviews, and conditions (half-cell or full cell, upper voltage, temperature) differ from paper to paper. The synthesis conditions from Argonne National Laboratory are model assumptions, not the conditions of any real manufacturer. Statements by Li and co-authors (cobalt quantities, the share of gradient materials and so on) date from 2019. All figures are explanatory concept graphics. Figs. 1, 2, 3, 4, 5 and 7 are vector drawings; Fig. 6 and the hero image are AI-generated images, and none of them shows a real cross-section, micrograph or physical product.