Silicon Anode Material Patent Landscape — Three Approaches to Expansion Control

What Is at Issue: Silicon Anode Patents Are a Numbers Fight Over “How to Contain the Silicon”

Rights in silicon anode patents rest not on silicon itself but on numbers that define in what ratio the silicon is confined within a framework such as an oxide, a metal, carbon, or magnesium silicate. And those rights are not permanent. Of the two representative patents covered here, the metal-doped silicon oxide patent KR101427743B1 is shown by Google Patents as lapsed for non-payment of annual fees, while Daejoo Electronic Materials’ carbon-silicon composite oxide patent KR102374350B1 (published as KR20200144855A) remains in force after grant.

Looking first at the industry context, a research paper published in 2008 explains that silicon has the highest known theoretical charge capacity (4,200 mAh/g), more than ten times that of existing graphite anodes. In Korea, the original article reported that MK Electron entered the material space in 2024 by registering a patent for a cold isostatic pressing (CIP, forming by applying equal pressure from all directions) process, while companies such as Daejoo Electronic Materials and POSCO Silicon Solution have accumulated over 200 related patents to stake out the market.

The tension is volume. The same paper points out that silicon’s volume changes by 400% as it takes in and releases lithium, causing pulverization and capacity fading. How to suppress this is the central axis of patent competition. This article answers three questions: what are the three approaches to expansion control, what and how far do the representative patents claim, and how does the “lifespan” of a right change the FTO (freedom-to-operate) judgment?

Basic Principle: How to Box Silicon That Puffs Up Like Popcorn

Up to 4.4 lithium ions can insert into a single silicon atom to form an alloy, and this process causes the crystal structure to expand significantly. Repeated charge/discharge cycles create cracks inside the electrode and cause active material to detach from the current collector, sharply reducing cycle life.

Fig. 1. A concept diagram of the path by which silicon swells as it alloys with lithium, leading through cracking and detachment to cycle-life loss.
Source: reconstructed by the editorial team from Chan et al. (Nature Nanotechnology, 2008) and the original article's explanation

By analogy, a silicon particle is a popcorn kernel that puffs up with every charge and shrinks again on discharge. Each time it puffs up it pushes against its surroundings, and the box that is the electrode cannot hold. The solutions fall into three kinds: changing the composition so the kernel puffs less (doping / oxidation), wrapping the kernel in a tough shell to spread the force (compositing / coating), or leaving room for it to puff from the start (nanostructure control).

Doping / oxidation: forming Si into SiOx and doping it with metal to mitigate the expansion itself
Compositing / coating: wrapping silicon in carbon, graphite, or a silicate matrix to disperse stress
Nanostructure control: pre-securing expansion space via pore and nanoparticle arrangement

Comparison: Three Approaches and Representative Patents

The first table below keeps the original article’s classification of approaches and adds the applicants and statuses of the representative patents.

Approach	Core idea	Representative patent	Applicant / status (Google Patents)
Doping / oxidation	Forming Si into SiOx and doping it with metal to mitigate the expansion itself	KR101427743B1	Yeil Electronics / Lapsed (annual fee unpaid)
Compositing / coating	Coating a silicon composite oxide surface with carbon to relieve grain-boundary stress	KR20200144855A (granted as KR102374350B1)	Daejoo Electronic Materials / Active
Nanostructure control	Pre-securing expansion space via pore and nanoparticle arrangement	Daejoo Electronic Materials patent family	Individual numbers not identified

Fig. 2. Three approaches to silicon anode expansion control and representative patents
Source: compiled by the editorial team from the original article’s classification and the bibliographic data of KR101427743B1 and KR102374350B1

What this table says: Among the three approaches, the representative doping / oxidation patent has already lapsed, while the representative compositing / coating patent may remain in force until 2039. Even among “silicon anode patents,” the timetables of the rights differ.

Item	KR101427743B1	KR20200144855A / KR102374350B1
Core composition	SiMxOy (M: transition metal not reacting with Li)	Silicon-based active material + SiOx (0<x≤2) + magnesium silicate crystals, carbon-coated
Key numerical limits	0.1≤x≤1.0, 0.01≤y<2	0.5 < oxygen atomic ratio / (silicon + magnesium atomic ratio) < upper bound
Dependent limits (published claims)	–	Si crystallite 2–10 nm, carbon 2–20 parts by weight, specific surface area 3–20 m²/g (claim 11)
Example capacity	1,210–1,600 mAh/g	–
Example efficiency	Ni-doped SiOx 84% or higher	–
Filing date / grant date	2012-06-13 / 2014-08-06	2019-06-19 / 2022-03-16

Fig. 3. Claimed compositions, numerical limits, and specification examples of the two representative patents compared
Source: compiled by the editorial team from the claims and specifications of KR101427743B1, KR20200144855A, and KR102374350B1

What this table says: The doping patent presents 1,210–1,600 mAh/g capacity and 84% or higher efficiency in its examples, while the Daejoo Electronic Materials patent narrows its rights by atomic ratio and crystallite size. All figures are values stated by the applicants.

Patent Perspective: Lapsed Rights and Living Rights

KR101427743B1 (“Metal-Doped Silicon Oxide, Anode Material for Secondary Battery Including the Same, and Method of Manufacturing the Same”) was filed by Yeil Electronics on June 13, 2012 and granted on August 6, 2014. Claim 1 covers a silicon oxide anode material represented by the formula SiMxOy, in which a transition metal element that does not react with lithium is doped into the lattice of a SiOx (0<x<2) crystal structure, with x of 0.1–1.0 and y of 0.01 or greater but less than 2. The specification lists Ni, Fe, Ti, Co, Ge, Ca, Al, and others as doping elements, with Ni preferred. Its distinguishing feature is lowering oxygen content to reduce initial irreversible capacity loss while the doping metal controls both particle size and volume expansion.

The original article said that a follower company would need to step outside the doping element or oxygen-content range to design around this patent. However, Google Patents shows the status of this patent as lapsed for non-payment of annual fees (Expired – Fee Related). If the right has lapsed in Korea, this claim scope is no longer something to design around; rather, it is likely to function as prior art for assessing the novelty and inventive step of later SiOx metal-doping applications.

KR20200144855A (“Carbon-Silicon Composite Oxide Composite for Anode Material of Secondary Battery and Method for Preparing the Same”) was filed by Daejoo Electronic Materials on June 19, 2019, published on December 30, 2020, and granted as KR102374350B1 on March 16, 2022 (Active, anticipated expiry June 19, 2039). Family members WO2020256395A2 and KR102452874B1 are listed. Claim 1 covers a composite containing a silicon-based active material, a silicon oxide-based active material (SiOx, 0<x≤2), and magnesium silicate crystals, with a carbon-coated surface, in which the oxygen atomic ratio divided by the sum of the silicon and magnesium atomic ratios is greater than 0.5 and less than a specified upper bound. The specification explains that it suppresses volume change during charge and discharge to relieve stress at grain boundaries.

Fig. 4. A map of the claim 1 elements of KR102374350B1 and the design-around potential of each.
Source: reconstructed by the editorial team from the claims of KR102374350B1 and KR20200144855A

The original article presented this patent’s core claim as “carbon coating of a silicon composite oxide with mixed amorphous and crystalline grain boundaries” and “a specific surface area of 3–20 m²/g.” On checking, the 3–20 m²/g specific surface area is a dependent limitation in published claim 11, and the core of the independent claim is the magnesium silicate crystals and the atomic ratio relation. Granted claim 1 does not include specific surface area either.

Insight: silicon anode FTO should start with a “legal status filter.” The fact that a 2012 doping patent lapsed for non-payment of annual fees means early SiOx-family rights are already passing into the public domain. By contrast, rights filed in 2019 or later — such as composite oxides containing magnesium silicate — may remain in force until around 2039. Ultimately, the difficulty of design-around may depend less on the technical approach than on “which generation of rights one runs into.”

Design-around points: Design-around options for claim 1 of KR102374350B1 are a composition that does not contain magnesium silicate crystals, or a composition outside the atomic ratio relation. A design without carbon coating would literally lack one element, but the need for conductivity leaves little realistic room.

Design-around scenario (counterargument): A design that uses a different metal silicate instead of magnesium may avoid literal infringement. However, if it achieves substantially the same function (suppressing volume change during cycling to relieve grain-boundary stress) in substantially the same way, it may become subject to a doctrine-of-equivalents analysis. In addition, because Daejoo Electronic Materials holds related family members (such as KR102452874B1), avoiding one patent may still leave exposure to adjacent rights.

Limitations and Outlook

Doping and compositing technologies lower the expansion rate but do not eliminate it entirely. The original article reported that the industry has so far limited itself to blending in silicon at a modest 5–15% level — not so much a limitation of the patented technology itself, but because the volume change that remains still places a burden on cell design (jelly-roll pressure, case rigidity). The next stage of competition may shift from the anode itself toward cell-structure patents such as cases and pressure plates that absorb the expansion.

There is also a counter-scenario. As early SiOx rights lapse and the base technology passes into the public domain, materials competition may become a contest of cost and mass-production quality rather than patents. In that case, even first movers that have built up more than 200 patents may find it hard to maintain entry barriers on grant counts alone.

A strategic alternative is to reclassify one’s own and competitors’ patents not only by approach (doping, coating, nanostructure) but along two axes: “generation (filing year)” and “legal status.” Managing lapsed rights as a basis for free practice and as invalidity material, and living rights as targets for licensing or design-around, lets the same staff cover a wider FTO scope.

Practical action: Planning and IP staff reviewing silicon anode materials should update the legal status of competitors’ patent lists (including annual fee payment) at least once a year, and keep lapsed patents in a separate list as prior-art material.

Items requiring verification

The registration number and claim scope of the cold isostatic pressing (CIP) process patent MK Electron registered in 2024
The counting basis and source of “more than 200” silicon anode patents held by Daejoo Electronic Materials and POSCO Silicon Solution
The upper bound of the atomic ratio relation in KR102374350B1 (the Korean text and English translation on Google Patents show 1.05 and 1.50 respectively)
A primary source for the industry silicon blending ratio of 5–15%
The lapse date of KR101427743B1 and whether any restoration was requested

Sources

Google Patents, KR101427743B1 bibliographic data, claims, and specification
Google Patents, KR20200144855A bibliographic data and claims (Korean and English)
Google Patents, KR102374350B1 bibliographic data and claims
Chan, C. K. et al., “High-performance lithium battery anodes using silicon nanowires,” Nature Nanotechnology (2008)