Open up a large-format cylindrical battery cell — the fat, can-shaped cells that increasingly sit under EV floors — and most of the interesting engineering is at the two ends. That is where the wound-up electrode sheet, the "jelly roll," has to hand its current off to the outside world, and where the cell has to be able to blow off pressure safely if something goes wrong. A patent granted June 30, 2026, US12671150B2, "Cylindrical battery cell, and battery pack and vehicle including the same," is a compact lesson in how those two jobs can be collapsed into a single part.

Here is the everyday stake first. Energy density — how much charge a cell holds for its weight and volume — is set not only by chemistry but by how much of the can is active material versus hardware. Every millimeter spent on a separate current-collector plate, a separate cap, and a separate vent disk is a millimeter not spent on jelly roll. The disclosed cell attacks that overhead by making one component do three things.

“A cylindrical battery cell includes a battery can accommodating a jelly-roll type electrode assembly therein, and a cap covers and closes an open end of the battery can. The cap is bonded to a tab of an electrode of the electrode assembly. The cap includes two or more electrode connecting portions, each of which protrudes into the interior of the battery can along the axial direction…”— U.S. Patent No. 12,671,150 source

How the mechanism works

Start with the tab. In an older cylindrical cell, a thin metal tab is welded to the electrode and then routed to a terminal — a small conductor carrying the whole cell's current, which limits fast-charge and fast-discharge because it heats up. The "tabless" generation, which this cell belongs to, instead leaves a long uncoated edge of the electrode foil exposed along the winding, so current can leave the whole height of the roll at once. The disclosed cap has electrode connecting portions — fingers of the cap metal that push down into the can along its axis and weld directly onto that exposed edge. The cap is no longer just a lid; it is the current-collector plate, monolithically formed, making broad electrical contact instead of a single pinched tab.

Now the safety half. The same cap carries a vent: a circumferential weakened line scored into the metal that divides it into an outer ring, welded to the can wall, and an inner region carrying those electrode fingers. Under normal use the whole cap conducts. If internal pressure spikes — the classic precursor to thermal runaway — that weakened line is designed to rupture. Breaking it does two things at once: it opens a path to vent the gas, and it severs the electrical connection between the electrode fingers and the can, disconnecting the cell as it releases pressure. Dependent claims add refinements a manufacturer would care about: four connecting fingers equally spaced, a central protruding region with a liquid inlet for electrolyte filling, and a stopper to close that inlet.

Two more details in the claims are worth pausing on because they are where clever cell design usually hides. First, electrolyte filling: the cap carries a liquid inlet in a central protruding region, and the manufacturing claims fill the assembled can through that inlet and then plug it with a stopper — so the same part that collects current, closes the can, and vents also becomes the fill port, again saving a dedicated feature elsewhere. Second, the join itself: a method claim has the connecting fingers bonded to the tab by laser irradiation of the cap's outer surface, welding through the cap from outside after the cell is closed. That sequencing matters, because welding a broad collector interface reliably is one of the harder steps in building these cells, and doing it from the outside is what makes the integrated cap manufacturable rather than merely elegant on paper.

The rest of the cluster of grants that issued the same day fills in the family around this cell. A companion grant, US12671146B2, describes the same wound assembly with a spacer set between the current collector and the cap to control the gap precisely; another, US12671138B2, covers a related cell whose venting cap connects to the can and one uncoated portion while a separate terminal reaches the other. Read together, they describe one coherent architecture for a large, high-rate cylindrical cell rather than three unrelated ideas.

Where it sits in the state of the art

The tabless, large-diameter cylindrical cell is the defining hardware bet of this EV-battery cycle, and the disclosures here are recognizably part of that lineage: maximize the uncoated-edge contact, integrate the current path into structural parts, and push the vent into the cap so the cell can fail gracefully at higher energy density. The pack- and module-level grants from the same drop show the other end of the same problem — getting heat out of a dense array of these cells. One, US12671127B2, puts the heatsink on top of the pack and has the cover contact the top surface of the modules; another, US12671128B2, runs an air-circulation duct with graduated hole sizes and an exhaust fan between cell stacks; and US12671124B2 integrates cooling and a fire-extinguishing fluid into one module wall.

It is worth being clear about what changes and what does not. The cap trick does not alter the cell's chemistry — the lithium-ion electrochemistry inside the jelly roll is unchanged — so the energy-density gain here is a packaging gain, won by shrinking inactive hardware, not a leap in what the active materials store. That is a meaningful distinction: packaging gains are incremental and cumulative, the kind of single-digit-percent wins that compound across a pack of thousands of cells, whereas chemistry gains are larger but rarer. The tabless architecture also unlocks the high-rate behavior separately, because current leaving the whole edge of the foil at once means lower internal resistance and less heating during a fast charge — which is exactly why the same drop spends so much effort on getting heat out at the module and pack level.

The honest framing: a granted patent describes a design, not a shipping product, and none of this says which cell format ultimately wins the pack. What the record does show is the engineering logic clearly. In a cylindrical cell, the ends are scarce real estate, and the physics rewards anyone who can make a single stamped-and-scored cap serve as collector, closure, and safety valve without stealing volume from the roll. That is the actual mechanism behind the marketing phrase "higher energy density" — fewer dedicated parts, more active material, and a vent that does its job by breaking exactly where the designer scored it.