Cobalt-Free High-Nickel Cathode Patents — Solving Thermal Stability Above 90% Nickel

What Is the Issue: A Claim That Stops at the 90% Nickel Threshold

Most thermal-stability patents for high-nickel cathode materials address the problem through a “coating that wraps the surface” or a “compositional gradient inside the particle,” but a close look at published claims shows that the scope of rights sometimes ends around 90% nickel. This means the region above 90% nickel still has many blank areas, both technically and on the rights map.

Starting with the industry landscape, EcoPro BM is a company that has grown on NCA and NCM cathode materials with nickel content of 80% or more. According to a report on its 2024 business report filed in March 2025, high-nickel products with 80% or more nickel accounted for 99.8% of cathode material revenue, and the company set targets of commercializing cobalt-free (NMX) cathode materials in 2026–2027 and high-manganese (OLO) cathode materials in 2027. The company’s R&D introduction also puts forward the development of products with nickel content of 90% or more, together with single-crystal and coating/doping technologies, as core tasks.

The source of tension is that raising the nickel share increases energy density but also increases structural instability and the risk of heat generation. This article answers three questions: what happens at the surface of high-nickel materials, how does the scope of rights differ between the representative coating patent KR101913939B1 and EcoPro BM’s core-shell gradient (CSG) technology, and what should IP staff watch as the field moves above 90% nickel and toward cobalt-free materials?

Basic Principle: The Juicier the Fruit, the Weaker the Skin

High-nickel cathode materials (NCM: nickel, cobalt, manganese; NCA: nickel, cobalt, aluminum) deliver more discharge capacity the higher their nickel share. A study comparing layered cathode materials by composition (Noh et al., 2013) reported that as nickel content increases, discharge capacity and residual lithium both rise, but capacity retention and safety gradually decline. The researchers concluded that structural stability is linked to thermal and electrochemical stability.

Fig. 1. A concept diagram comparing coating and compositional-gradient approaches to protecting high-nickel cathode surfaces by treatment timing and rights layer.
Source: reconstructed by the editorial team from the claims of KR101913939B1 and a report on EcoPro BM's CSG (Electronic Times, 2021-03-07)

By analogy, a high-nickel particle is like a very juicy fruit. The more juice (capacity) it holds, the weaker its skin (surface structure) becomes, so with repeated charge and discharge, oxygen escapes from the surface and cation mixing, in which nickel ions migrate into lithium sites, progresses. The weakened surface then causes side reactions with the electrolyte and generates gas, and in severe cases this can lead to thermal runaway. There are two broad response strategies.

Adding a skin (surface coating): applying a stable layer to the surface of the finished particle to reduce direct contact with the electrolyte.
Growing a thicker skin from the start (compositional gradient): designing the composition during particle synthesis so that the center is rich in nickel and the outside is rich in stabilizing elements.

Both strategies are technologies that protect the surface. The difference lies in whether the treatment is a post-process after synthesis or part of the synthesis step itself, and this difference translates directly into a difference in the layer of patent claims.

Comparison: The Rights Layers of Coating, Compositional Gradient and Cobalt-Free

The table below organizes technologies for high-nickel thermal stability by treatment timing and rights layer. Only figures confirmed in patent examples or company announcements are listed.

Item	Organic sulfonate coating (KR101913939B1)	Core-shell gradient (CSG)	Cobalt-free (NMX)
Treatment timing	Wet coating after synthesis + heat treatment	Particle synthesis stage	Composition design stage
Target composition	LiNi_xCo_yMn_zO₂, 0.6 ≤ x ≤ 0.9	High-nickel core, manganese and cobalt placed toward the surface	Composition without cobalt
Published performance figures	Capacity retention 97.4% after 50 cycles at 1C (untreated 86.5%), discharge capacity 174.0 mAh/g	Not verified in this article	Not verified in this article
Right holder / origin	Incheon National University Industry-Academic Cooperation Foundation	Commercialization of a Hanyang University industry-academic cooperation patent (per press reports)	EcoPro BM commercialization target 2026–2027
Rights layer	Coating method claims	Possible particle structure/composition claims	Possible composition claims

Fig. 2. Comparison of treatment timing and rights layer for high-nickel cathode thermal-stability technologies
Source: KR101913939B1 (Google Patents), reports by Electronic Times (2021-03-07) and The Elec (2025-03-18)

What this table says: the example in KR101913939B1 states that capacity retention of NCM811 after 50 cycles at 1C rose from 86.5% to 97.4%, but the claimed composition is limited to 60–90% nickel. Coating, compositional gradient and cobalt-free approaches differ in treatment timing and should be seen as rights at different layers.

Patent Perspective: The Distance Between a Coating Method Claim and a Compositional Gradient

KR101913939B1 (title: Organic additive coating method for improving interfacial stability of cathode material for lithium secondary battery) is a granted patent filed by the Incheon National University Industry-Academic Cooperation Foundation on April 17, 2017 and published upon grant on October 31, 2018. According to Google Patents, its legal status is Active and its anticipated expiration date is April 17, 2037.

Claim 1 is a method claim consisting of three steps. Restated, it reads as follows.

S1: Prepare a high-nickel cathode active material of LiNi_xCo_yMn_zO₂ (0.6 ≤ x ≤ 0.9, 0.05 ≤ y ≤ 0.2, 0.05 ≤ z ≤ 0.2).
S2: Add the cathode active material to a coating solution containing N,N-dimethylpyrrolidinium methyl sulfate and stir to wet-coat an organic precursor.
S3: Separate the coated material and heat-treat it to fix a sulfonate layer.

The dependent claims narrow the scope with a coating amount of 1–10 wt% (5 wt% optimal in the examples), NMP as the solvent, heat treatment at 550–650°C under atmospheric pressure (600°C for 3 hours in the examples), and NCM811 as the target material. Against a mainstream of inorganic coatings, it chooses an organic precursor, and its goal is to stabilize the interface between electrolyte and active material through heat treatment and reduce side reactions.

Fig. 3. A diagram restating the elements of claim 1 of KR101913939B1 and mapping the design-around potential of each.
Source: reconstructed by the editorial team from claim 1 of KR101913939B1 (Google Patents)

Insight: the scope of this patent ends exactly where the “90% nickel and above” discussion begins. Claim 1 caps the nickel ratio x at 0.9 or less. Therefore compositions exceeding 90% nickel, such as the 95% nickel cathode material EcoPro BM said in 2021 it had finished developing, may fall outside the literal scope of this claim. The need for coating grows as materials move to ultra-high nickel, yet a representative published coating patent stops just before that point, which suggests room remains for new filings in the region above 90%. At the same time, a composition with x = 0.9 sits on the boundary of the claimed range, so those developing 90% nickel products should not exclude this patent from FTO (freedom-to-operate review).

CSG technology sits at a different layer. According to press reports, EcoPro BM’s CSG raises the nickel content in the particle center (core) while placing manganese and cobalt, which strengthen safety, and it is a commercialization of a patent from the Hanyang University industry-academic cooperation foundation. If coating is a method invention claiming an “external treatment” after synthesis, a compositional gradient is likely to take the form of a product invention claiming the structure or composition of the particle itself. Therefore, designing around a coating patent does not settle the relationship with a compositional gradient patent, and vice versa.

Design-around points: KR101913939B1 requires wet coating with a coating solution containing a specific compound (N,N-dimethylpyrrolidinium methyl sulfate) and a heat-treatment step. On the literal wording, using a different sulfur-containing precursor, or choosing dry coating or a process without heat treatment, may lack this element. Compositions above 90% nickel, or compositions such as NCA that use aluminum instead of manganese, may also fall outside the compositional limitation of claim 1.

Design-around scenario (counterargument): However, if a structurally similar pyrrolidinium-based sulfate precursor is used to obtain the same sulfonate layer in the same way, it may become subject to a doctrine-of-equivalents analysis. Conversely, from the patentee’s side, research on stabilizing cathode interfaces with sulfonates or sulfur-containing compounds has been carried out widely in the electrolyte additive field, so the inventive step of the claim may be contested against the prior art. Ultimately, design-around potential and the stability of the right can only be judged by comparing individual process conditions with the prior art together.

Limits and Outlook

The optimistic outlook is that, as coating, compositional gradient and single-crystal technologies are layered on top of one another, cathode materials with 90% or more nickel will also be mass-produced stably. There is also a counter-scenario. Since research has reported a tendency for capacity retention and safety to decline together as nickel share rises, there may be limits to securing the thermal stability of ultra-high nickel through surface treatment alone. In that case, ultra-high-nickel coating patents could end up as rights that exist but have few products to be practiced in.

This trend can also be read in the direction of EcoPro BM’s portfolio. In a situation where high-nickel products account for 99.8% of revenue, the company’s broadening of its development targets to cobalt-free (NMX), high-manganese (OLO), LFP and sodium-ion cathode materials can be interpreted as preparation for the possibility that the center of gravity of competition shifts from “adding more nickel” to “preserving energy density while reducing dependence on nickel and cobalt.”

The strategic alternative is to draw the high-nickel patent map by composition band. Distinguishing the 60–90% nickel band as a region where coating and gradient patents overlap densely, and the above-90% and cobalt-free bands as regions with relatively more room for new filings, makes it clear at a glance what density of rights each product on a company’s roadmap sits within.

Practical action: Planning and IP staff developing or procuring high-nickel cathode materials should first tabulate their products’ nickel ratio x and surface treatment process (wet or dry, heat-treatment temperature), and then check whether they overlap with the compositional range (0.6 ≤ x ≤ 0.9) and process steps of claim 1 of KR101913939B1.

Items requiring verification

The number, claims and status of the Hanyang University industry-academic cooperation patent underlying EcoPro BM’s CSG technology
Whether KR101913939B1 has foreign family filings or has been licensed or transferred
Whether EcoPro BM’s 2025 business report (filed in 2026) changed the commercialization schedule for cobalt-free (NMX) materials
Filing trends for coating and doping patents claiming compositions above 90% nickel

Sources

Google Patents, KR101913939B1 – Organic additive coating method for improving interfacial stability of cathode material for lithium secondary battery (Incheon National University Industry-Academic Cooperation Foundation)
The Elec, “EcoPro BM: high nickel alone has limits… accelerating portfolio expansion” (2025-03-18)
Electronic Times, “[Listed company analysis] EcoPro BM’s high-nickel cathode development results… ‘aiming for world No. 1′” (2021-03-07)
EcoPro BM, R&D fields introduction page
Noh H.-J., Youn S., Yoon C. S., Sun Y.-K., “Comparison of the structural and electrochemical properties of layered Li[NixCoyMnz]O2 (x = 1/3, 0.5, 0.6, 0.7, 0.8 and 0.85) cathode material for lithium-ion batteries”, Journal of Power Sources 233 (2013) 121–130