What Is at Issue: Dry Electrode Patents Fight Over “What Film” More Than “How to Make It”
The core of the dry electrode patent contest is not the name of the process but the numbers and elements written into the claims. LG Energy Solution’s WO2022164120A1 draws its claim scope with a film property — “a tensile strength of 2,000 gf/cm² or more based on a thickness of 200 μm” — while US20260031317A1, published by Tesla on January 29, 2026, claims the mixing and calendering steps for a dry film with reduced binder. Even under the same “dry electrode” label, one side holds the result (the film) and the other holds the process (the mixing sequence). That is the starting point of this article.
Looking first at the industry context, the dry electrode (an electrode formed directly from powder into a film without solvent) can skip the slurry drying step and makes thick electrodes easier to produce, so it is regarded as a key technology for lowering 4680 battery mass-production costs. Tesla completed its acquisition of Maxwell Technologies on May 16, 2019, and the dry process has since been cited almost as a symbol of Tesla’s battery strategy. LG Energy Solution has responded by securing patents on dry films and manufacturing apparatus.
The tension lies in the fact that the rights sit on different “layers.” A patent claiming film properties may create grounds for infringement whenever the resulting film falls within the numerical range, whatever process was used to make it. Conversely, a patent claiming a process may leave a product outside its scope if the steps differ, even when the result is the same. This article answers three questions: what principle holds a dry film together, what and how far do the two camps’ claims reach, and where should planning and IP staff begin their FTO (freedom-to-operate) review?
Basic Principle: A “Fiber Net” That Binds Dough Without Water
In the conventional wet process, active material, binder, and conductive additive are mixed with a solvent to form a slurry, which is coated onto the current collector and dried. The dry process eliminates this slurry step, forming powder-state materials directly into a film using shear force (a force that twists material by sliding it sideways). The key is fibrillizing a binder such as PTFE (polytetrafluoroethylene) so that it entangles the powder particles like a net.
Source: reconstructed by the editorial team from the specification and claims of WO2022164120A1 and KR102707066B1
By analogy, it resembles making flour dough without water. Without water the powder does not stick together, but if the dough contains threads that stretch thin (PTFE fibers), those threads catch the grains like a spider web and tie them into a single sheet. This fibrous structure lets the film hold its shape without any adhesive. The question is how tough the sheet is and how uniform its thickness comes out — and that is exactly what LG Energy Solution’s patent claims.
The manufacturing apparatus described in LG Energy Solution’s patent is built as follows.
- Storage: a body holding the solvent-free mixture
- Extrusion: an extruder that forms and discharges the fibrillized composition
- Preforming rolls: a pair of counter-rotating rolls that shape the composition into a film (optionally with a pre-mixer and calender)
The specification presents the use of preforming rolls instead of a slit guide — enabling quantitative extrusion while minimizing load — as its key improvement. In other words, the property target of “uniform thickness” and the apparatus means of “roll-based preforming” are paired within one patent.
Comparison: Wet Process, LG Energy Solution’s Film Patent, and Tesla’s Published Application
The table below places the general process against the claimed configurations of the two patent documents. All figures are values stated in patent claims, not measured performance.
| Item | Wet process (general) | LG Energy Solution WO2022164120A1 | Tesla US20260031317A1 |
|---|---|---|---|
| Solvent | Slurry solvent used, then dried | Solvent-free mixture extruded | Specification: some embodiments use no solvent at any stage |
| Focus of claims | – | Film properties (product) + apparatus | Mixing, binder addition, and calendering steps (method) |
| Key numerical limit | – | Tensile strength of 2,000 gf/cm² or more at 200 μm | No numerical limit in claim 1 (single fibrillizable binder) |
| Further limit | – | Thickness deviation of 0.5% or less (KR granted claim) | Nondestructive mixing of cathode active material + porous carbon |
| Priority date | – | 2021-01-27 | 2018-05-14 |
| Legal status (Google Patents) | – | KR102707066B1 granted, Active; US application Pending | Pending |
Source: compiled by the editorial team from the claims and bibliographic data of WO2022164120A1, KR102707066B1, and US20260031317A1
What this table says: LG Energy Solution builds its rights on product figures — 2,000 gf/cm² tensile strength and 0.5% thickness deviation — while Tesla’s published application builds them on process steps without numbers. Because the two rights cover different objects, avoiding one does not mean avoiding the other.
Patent Perspective: Where Product Claims and Method Claims Cross
Bibliographic data (LG Energy Solution): WO2022164120A1 (“Free-Standing Film for Dry Electrode, Manufacturing Apparatus Therefor, Dry Electrode Comprising the Same, and Secondary Battery”) claims priority from Korean application 10-2021-0011773 filed on January 27, 2021; the international application was filed on January 19, 2022 and published on August 4, 2022. Family members include KR102707066B1 (granted September 13, 2024; Active per Google Patents; anticipated expiry January 13, 2042), US20230178754A1 (Pending), EP4102593A4, JP7501970B2, and CN115398664B.
Claim summary (restated): The independent claim covers a free-standing film consisting of binder, active material, and conductive additive that has a tensile strength of 2,000 gf/cm² or more based on a thickness of 200 μm. The Korean granted claim also recites a thickness deviation of 0.5% or less. Separate independent claims cover a manufacturing apparatus with a body storing a solvent-free mixture, an extruder, and a pair of preforming rolls; a dry electrode in which the film is attached to a primer-coated current collector; and a secondary battery including it.
Source: reconstructed by the editorial team from the claims of KR102707066B1 and WO2022164120A1
Bibliographic data (Tesla): US20260031317A1, published January 29, 2026, is titled “Compositions and methods for dry electrode films having reduced binder content”; the applicant is Tesla Inc, with a priority date of May 14, 2018, a filing date of August 15, 2025, and Pending status. Claim 1 is a method of nondestructively mixing a cathode active material and a porous carbon (optionally with a conductive carbon), adding a single fibrillizable binder and nondestructively mixing again, and then calendering to form a free-standing film.
Insight: a 2018 priority date changes both the “in-house development” narrative and the FTO landscape. The priority date of this application precedes the completion of the Maxwell acquisition (May 16, 2019). It is therefore difficult to conclude that this document is the result of in-house development after the acquisition. More important is the FTO angle. Published documents in a family with a 2018 priority date may be reviewed as prior art against later dry-film patents with 2021 priority dates. Conversely, because LG Energy Solution’s film claims do not ask how the film was made, even a film produced by a Tesla-style process may need to be reviewed for infringement risk if its tensile strength and thickness deviation fall within the numerical ranges. The two rights can serve as both shield and spear against each other.
Design-around points: There are two broad design-around options for LG Energy Solution’s claims. First, design the film so that its properties fall outside the numerical range. However, lowering tensile strength makes it harder to survive lamination, so the realistic room is narrow. Second, because literal infringement of the Korean granted claim requires every element including the thickness-deviation condition (the all-elements rule), the relationship with the deviation condition can be examined separately. The apparatus claim can be distanced by using a forming means other than preforming rolls.
Design-around scenario (counterargument): In numerically limited claims, however, the measurement condition is the claim scope. Because of the conversion condition “based on a thickness of 200 μm,” a film of a different actual thickness may still fall within range after conversion. Films exceeding the thickness-deviation threshold are also disadvantaged in quality, so a design that sacrifices quality for the sake of avoidance is hard to justify commercially. Ultimately, whether a design avoids the claim can only be judged by comparing one’s own film measurement data one-to-one with the measurement method in the specification.
The original article stated that Tesla’s patent specification claims a step of adding a small amount of solvent such as a hydrocarbon, acetate, or alcohol to selectively activate only the PTFE before applying shear force. However, claim 1 of US20260031317A1, published January 29, 2026, contains no solvent-addition step, and the specification states that some embodiments use no solvent at any stage. The document number for the “small amount of solvent” configuration the original referred to could not be identified in this review and is listed below as an item requiring verification.
Limitations and Outlook
The bottleneck for dry electrodes lies in uniform film thickness control and large-area lamination yield. That LG Energy Solution included thickness deviation and a primer-coated current collector in its claims can be read as targeting the same bottleneck. Patent competition is shifting from “how to make the film” to “how to reliably bond that film to the current collector,” and as 4680 battery mass production ramps up, lamination equipment and process patents may become the next battleground.
There is also a counter-scenario. If large-area lamination yield does not improve as hoped, automakers and cell makers may turn back toward improving solvent recovery and drying efficiency in the wet process. In that case, dry-film property patents could remain unpracticed rights, and their value as bargaining chips could shrink. In addition, since documents in the 2018-priority family are public, later numerically limited claims may become targets for novelty and inventive-step challenges in invalidation proceedings.
A strategic alternative is to track dry electrode rights across three layers: “film properties,” “forming apparatus,” and “lamination / current-collector interface.” Even if the process choice changes, rights on the interfacial adhesion layer may apply to both wet and dry processes, so securing that layer first is less exposed to process uncertainty.
Practical action: Planning and IP staff running trial production of dry films should record their film’s tensile strength converted to a 200 μm thickness basis and its thickness deviation, together with measurement dates and methods, to document numerically how far they sit from the claim scope of KR102707066B1.
Items requiring verification
- The publication number of the Tesla patent document the original cited for “selectively activating PTFE with a small amount of hydrocarbon, acetate, or alcohol solvent,” and whether this is recited in its claims
- The original applicant of the US20260031317A1 family and its relationship to Maxwell Technologies’ research
- The latest examination and grant status of US20230178754A1 (US), EP4102593 (Europe), and CN115398664B (China), and differences in granted claims
- Key dry electrode patent numbers and claim scope of Samsung SDI and SK On, the other members of the “Big Three” in the title
- The tensile-strength measurement conditions in the KR102707066B1 specification (specimen dimensions, pull rate)
Sources
- Google Patents, WO2022164120A1 bibliographic data and claims
- Google Patents, KR102707066B1 bibliographic data and claims
- Google Patents, US20230178754A1 bibliographic data and claims
- Google Patents, US20260031317A1 bibliographic data and claims
- Tesla, “Tesla Completes Acquisition of Maxwell Technologies” press release (2019-05-16)
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