Despite America’s recently suppressed appetite for electric vehicles, battery technology continues to advance. A promising development out of a Massachusetts Institute of Technology (MIT) lab discovery has recently come to light. A Cambridge-based company called 24M Technologies claims its “SemiSolid” battery architecture—designed to work with different existing technologies—can boost an EV’s range and charging time or shrink battery size and cost. Its new system is dubbed ETOP (Electrode-to-Pack), and it sounds like it could be the next big battery advancement beyond “cell-to-pack.” Here are the claims in detail:

The Problem with Today’s Battery Packs

Most of today’s EV batteries are built like nesting dolls. First, manufacturers create small, individual cells, each wrapped in its own casing with protective materials. These cells are then grouped into modules, which are finally bolted together into a pack. It’s safe and proven, but inefficient. Cell-to-pack architecture reduces some of that waste, but 24M says typical EV batteries only devote 30–60 percent of the pack’s volume to energy storage. The rest is just packaging, or “dead weight.”

What ETOP Does Differently

24M’s ETOP flips that script. Instead of wrapping energy-storing materials inside hundreds—or even thousands—of individual cells, the electrodes themselves get sealed in thin polymer films and stacked directly into the battery pack. No extra casings, no modules, minimal wasted space.

The result? Up to 80 percent of the pack’s volume is now active material (the part that actually stores energy), thereby boosting energy density, which can translate to longer driving range, smaller/cheaper battery packs, or a mix of both.

What Do These “Cells” Look Like?

Each electrode gets coated in an electrolyte material, then a separator gets rolled on, sandwiched between the other electrode. The pair is then sealed inside a thin polymer film. The 24M “Impervio” separator itself consists of a conductive layer sandwiched between two insulating polyethylene (PE) layers. The proprietary tech is said to actively suppress the growth of metal dendrites that will short a cell and can start a fire if they extend far enough to connect electrodes. These thin cells remain individually addressable for monitoring of voltage and faults by the battery management system. In contrast to prismatic cells, which consist of electrode material bathed in shared, flammable electrolyte, here the electrolyte is discretely sealed in with the electrodes.

What Does “SemiSolid” Mean Here?

24M’s proprietary “Eternalyte” electrolyte is a liquid that claims to offer high ionic conductivity with multiple different cathode chemistries, to enable extremely fast charging speeds—like a claimed 200 miles of range in under four minutes. Eternalyte is also claimed to retain high performance at low temperatures (-40 degrees). Rather, 24M has trademarked “SemiSolid” to refer to its manufacturing process, which requires no binders or drying agents. The resulting clay-like “semi-solid” electrodes are thicker but include much more battery active material, further improving claimed energy density.

What That Means for EV Drivers

A 75-kWh pack (common in today’s mid-size EVs) could hold over 100 kWh of energy using the same chemistry and the same space—roughly a 33–50 percent range boost. Or, automakers could swap in cheaper, safer chemistries like LFP (lithium-iron phosphate) while keeping today’s ranges intact. That means EVs could become more affordable without compromising usability.

Packaging Benefit

In addition to eliminating dead material, the 24M manufacturing process allows the electrode/separator sandwiches to be trimmed to any size or shape and hence can better adapt to unused spaces in a vehicle (like the wings of an electric plane). In cars, this could can lead to lower floors for better legroom and more cargo area.

Cheaper to Make?

24M claims its process involves fewer precision manufacturing steps, resulting in lower factory costs, higher yields, and a simplified quality control process. By simply flipping the cells, they can be easily wired in parallel or series, making it easier to achieve the desired voltage, say 48V for hybrids, or 400/800-volt switchable packs for fast charging, etc.

The Big Picture

Think of ETOP as the battery-design equivalent of the way you can always get more dirty clothes into your carry-on bag when you don’t have to carefully fold them and place them just so. By eliminating wasted space, 24M’s tech could create a pathway to developing EVs and other electrified vehicles with longer ranges and blazing fast charging speeds, cheaper EVs in general, or potentially all of those benefits at the same time in the future—all things consumers want now.

Will 24M’s ETOP be a battery game changer? Gosh, we hope so, but the above description is derived from company line claims released this week, based on best-case, promising lab results. There’s little or no published material from battery experts weighing in on these claims, and the path to development is typically a long one. But we’ll certainly be pulling extra hard for this home-team development to go the distance.