4680 Cell Thermal-Management Structure Patents — The Next Battleground After Tabless

What Is at Issue: The Thicker the Cell, the More Heat Gets Trapped in the Core

In the race for 46mm-diameter cylindrical cells (the 46-series), the next patent battleground after tabless electrodes is “the path heat takes to escape.” As a cell gets thicker, its volume grows sharply but its surface area does not keep pace, making it harder for heat generated at the center of the jelly roll (the core) to get out. This article reads three published patent documents across three layers — cell electrode structure, cell interior, and module cooling — and sets out the scope of rights and the room for design-around at each layer.

Start with the industry context. In a report dated February 15, 2024, LG Energy Solution CEO Kim Dong-myung said the company was “planning to mass-produce 4680 batteries around August–September,” with the Ochang plant named as the production site. A later report dated January 21, 2025 said 4680 mass production at Ochang had begun after November 2024 and that the initial volumes were at the level of customer validation. Samsung SDI announced mass production of its 46-phi battery (4695, 46mm in diameter and 95mm tall) on March 31, 2025. It said the cells are produced on the mother line at its Cheonan site and that initial volumes go to a U.S. customer for micromobility use.

The source of tension is size itself. A simple calculation from external dimensions alone puts the volume of a 4680 at about 5.5 times that of a 2170. Surface area per unit volume, by contrast, falls to about half. If the tabless structure reduced heat generation by lowering electrical resistance, the next task for both design and patents is deciding which path the remaining heat should take out of the cell. This article answers three questions: where does heat accumulate in a large cylindrical cell, at which layer do the published patents claim a solution, and how should planning and IP staff divide up their FTO (freedom-to-operate) review?

Basic Principle: A Thick Log Takes a Long Time to Cool All the Way Through

A cylindrical cell is a jelly roll — cathode, separator and anode rolled up like a sushi roll — packed into a metal can. Heat is generated throughout the jelly roll during charging and discharging, but the only exit is the surface of the can. It is like firewood: a thin stick cools quickly, but a thick log stays hot inside even after its surface has cooled.

Fig. 1. A concept diagram showing that heat from the core of a large cylindrical cell escapes more readily along the current-collector foil in the axial direction than radially.
Source: concept diagram reconstructed by the editorial team from the specifications of WO2020096973A1 and US20240006722A1

Heat leaving the core has two main routes. One runs radially across the many layers of electrode and separator in the jelly roll. Every layer has a boundary, so heat does not cross easily. The other runs along the electrode current collectors (metal foil) toward the top and bottom of the cell — that is, in the axial direction. Metal foil conducts heat well, so this route widens when the foil edges make broad contact with the can bottom or a current-collector plate.

This is where the tabless structure connects to the thermal problem. The specification of Tesla’s WO2020096973A1 (title: “A cell with a tabless electrode”) states that the contact area between the can and a conductive portion running along the entire electrode length effectively occupies 100% of the cell diameter, improving heat transfer through the base of the cell, and especially heat transfer from the negative electrode. In other words, tabless is both a technology for shortening the electrical path and a technology for widening the axial heat-dissipation path.

Even so, the core problem remains. The specification of LG Energy Solution’s US20240006722A1 explains that as the outer diameter of the electrode assembly increases, the rate at which heat escapes outward from the core becomes slower, and that when heat does not escape from the core well, the separator may contract because of the high temperature in the core portion. The specification refers directly to 46mm-diameter cells.

Comparison: Cell Size, Heat-Dissipation Conditions, and Patent Layers

The first table below shows simple geometric values calculated from external dimensions (diameter and height) only. Can thickness, internal voids in the jelly roll and actual energy capacity are not reflected.

Format	Diameter (mm)	Height (mm)	Volume (cm³)	Volume vs. 2170	Surface area per volume (mm⁻¹)
2170	21	70	24.2	1.0x	0.219
4680	46	80	133.0	about 5.5x	0.112
4695	46	95	157.9	about 6.5x	0.108

Fig. 2. Volume and surface area per volume by cylindrical cell format (simple calculation from external dimensions)
Source: calculated by the editorial team from the dimensions implied by the format names; 4695 dimensions from Samsung SDI’s announcement (2025-03-31)

What this table says: A 4680 has about 5.5 times the volume of a 2170, but its surface area per unit volume falls to about 51% (0.219→0.112mm⁻¹). Samsung SDI’s announcement that the 4695 offers roughly 6 times or more the energy capacity of a 21700 points in the same direction as this volume difference.

Layer	Representative document	Applicant	Priority date	Status (Google Patents)	Thermal essence
Cell electrode structure	WO2020096973A1	Tesla Inc	2018-11-05	Ceased (PCT stage)	Electrode conductive portion contacts the can broadly, improving heat transfer through the base
Cell interior (core)	US20240006722A1	LG Energy Solution	2021-04-08	Pending (under examination)	Fixing part on the electrode edge nearest the winding center suppresses separator contraction
Module cooling	WO2017043889A1 / US10347880B2	LG Chem (now LG Energy Solution)	2015-09-08	WO: Ceased / US: Active (expected to expire 2037-02-10)	Cooling-fin bottom flange passes through a cooling-plate slit to contact its underside

Fig. 3. Comparison of published patents related to cylindrical-cell thermal management, by layer
Source: compiled by the editorial team from Google Patents bibliographic data, claims and specifications (WO2020096973A1, US20240006722A1, WO2017043889A1, US10347880B2)

What this table says: All three documents deal with “heat dissipation,” but what they claim differs — the electrode, the jelly-roll interior and the module, respectively. An FTO result at one layer therefore does not stand in for an assessment of infringement risk at another.

Patent Perspective: Scope of Rights Moving Inside the Cell

Correction to the original: The original described WO2017043889A1 (battery module having improved cooling performance) as a cooling design for a module of cylindrical cells. According to Google Patents, the applicant of this patent is LG Chem, and the cells assumed in the specification are pouch-type secondary batteries. Claim 1 consists of a plate-shaped cooling plate with slits, cells standing side by side on it, and cooling fins each having a wall surface contacting one surface of a cell and a bottom flange formed integrally with the wall that passes through a slit to contact the underside of the cooling plate. The dependent claims include a heat sink with coolant channels and thermally conductive metal materials such as aluminum alloy. This patent is therefore more accurately read as an example of “module-level heat dissipation” from the generation before cylindrical cells were scaled up.

Cell-interior layer: The gist of claim 1 of US20240006722A1 (applicant LG Energy Solution; priority date April 8, 2021; filing date April 7, 2022; publication date January 4, 2024) is a wound electrode assembly in which a first electrode has a fixing part on its electrode active material layer, positioned at the edge closest to the winding center and fixed to at least part of the separator. The specification cites a lamination tape with thermal stability as an example of the fixing part. According to Google Patents this application is still under examination (Pending), so the claims may change by the time it is granted.

Fig. 4. A diagram dividing claim 1 of US20240006722A1 into four elements and mapping the key limitation on fixing-part location, and the design-around potential of each element.
Source: reconstructed by the editorial team from the claims of US20240006722A1

Insight: the center of gravity of heat-dissipation patents is shifting from “parts that remove heat” to “structures that hold up while heat remains.” The module patent with a 2015 priority date focused on removing heat by increasing the contact area between the cooling plate and the cells. The tabless patent with a 2018 priority date used the electrode itself as a heat-dissipation path. LG Energy Solution’s application with a 2021 priority date starts from the premise that not all core heat will escape, and claims a way to mechanically hold the separator so it does not contract under that condition. The trend can be read as claim design reflecting a recognition that, as cells get thicker, “cooling” alone struggles to control core temperature.

Design-around points: The key limitations of US20240006722A1 are the location of the fixing part (the edge closest to the winding center) and what it is fixed to (the separator). A design that suppresses separator contraction on the materials side, such as with a heat-resistant coated separator rather than a fixing part, or one that places a hollow structure in the core to change the conditions under which heat accumulates in the first place, may lack this element. At the module level, the core of US10347880B2 is the “flange passing through the slit,” so bonding the cooling fin only to the top surface of the cooling plate or using fins formed integrally with the cooling plate could keep a design at a distance from the literal scope.

Design-around scenario (counterargument): However, if a design that moves the fixing part slightly or replaces the tape with another attachment member achieves substantially the same function (suppressing separator contraction in the core) in substantially the same way, it may be assessed under the doctrine of equivalents. An application under examination may also see its claims narrowed by amendment, or gain rights from a different angle through continuation filings. Rather than settling on a design-around based only on the current claims, it is therefore necessary to track the grant timing and family expansion together.

Limits and Outlook

Industry observers point out that as cells get larger, designing them to pass safety tests such as nail penetration also becomes more difficult. As long as the race to scale up cylindrical cells continues, heat-dissipation patents are likely to expand beyond cooling-plate design toward redesigning the heat-conduction path inside the cell itself — for example, by securing axial heat-dissipation paths.

There is also a counter-scenario. If, as the January 2025 report indicated, initial 4680 volumes stay at the customer-validation level and demand growth is delayed, cell-interior heat-dissipation patents may remain rights on paper without being practiced in actual products. In that case, their value as bargaining chips in cross-licensing negotiations may come to the fore before their value for enforcement.

The strategic alternative is to split the heat-dissipation FTO into three layers — electrode structure, cell interior and module cooling — and review each separately. In supply chains where the cell maker and the module/pack maker differ, the party bearing infringement risk may also differ by layer, so it is safer to design the IP-warranty clauses of supply contracts along the same layer divisions.

Practical action: Planning and IP staff adopting or developing 46-series cells should add the prosecution history and family filings of US20240006722A1 to their monitoring list, and map their own design’s treatment of the core-side separator (whether a fixing member exists and where it sits) one-to-one against the elements of claim 1.

Items requiring verification

The status of LG Energy Solution’s accumulated thermal-runaway-prevention patents mentioned in the original (specific patent numbers not confirmed)
The existence and number of the Tesla-side “dry-electrode adhesive passivation-film composition” patent mentioned in the original
Whether national-phase family members of WO2020096973A1, such as in the U.S., were granted, and their claims
Whether the Korean priority application (10-2021-0045993) and foreign family members of US20240006722A1 have been granted
The primary source for the industry observation about nail-penetration testing of large cylindrical cells

Sources

Google Patents, WO2017043889A1 / US10347880B2 bibliographic data and claims
Google Patents, WO2020096973A1 “A cell with a tabless electrode” bibliographic data and specification
Google Patents, US20240006722A1 “Electrode assembly, battery cell, battery pack, and vehicle” bibliographic data, claims and specification
TheElec, “LGES CEO Kim Dong-myung: 4680 battery mass production in Korea in August,” 2024-02-15
Digital Daily, “LGES began 4680 mass production late last year… volume expansion on pause amid Tesla slump,” 2025-01-21
Samsung SDI Newsroom, “Samsung SDI begins mass production of next-generation 46-phi battery, initial supply to U.S. customer,” 2025-03-31