The semi-solid thick electrode is a material science innovation originating in Dr. Yet-Ming Chiang’s lab at MIT. (Dr. Chiang, one of the founders of A123 Systems, is a co-founder and chief scientist for 24M.) Conventional lithium-ion battery cells have a large fraction of inactive, non-charge carrying materials—supporting metals and plastics—that are layered, one-on-top of the other, within a cell’s casing. Those inactive materials are expensive and wasteful.

With the invention of the semisolid thick electrode, 24M eliminates more than 80% of these inactive materials and increases the active layer thickness over traditional lithium-ion by up to 5x.

Schematic of a 24M cell, from the patent. Click to enlarge.		24M cell compared to conventional Li-ion cell. Click to enlarge.

Using thick electrodes, the cell also stores more energy, bettering the performance of the battery as well as its cost. The materials design enables up to 5x the area capacity of standard Li-ion.

Sepion Technologies’ vision is to develop ultra-light, high-power density Li-sulfur batteries for aviation. The company has developed a microporous polymer membrane to replace incumbent separator materials. In addition to providing high-flux and ion-selective transport, Sepion’s polymer membranes are processable in large area formats at a fraction of the cost of ceramics.

Sepion Technologies’ core membrane technology was developed at Berkeley Lab by Peter Frischmann and his co-founder, Molecular Foundry Staff Scientist Brett Helms. Frischmann left his position at Berkeley Lab to found Sepion Technologies earlier this year. He and his team are users at the Molecular Foundry where they continue to develop their technology.

Sepion’s scalable and low-cost microporous polymer membrane size-sieves lithium ions from polysulfides, effectively extending the cycle life of Li-S cells. Click to enlarge.

Lithium metal is recognized as an enabler of high-energy density in rechargeable batteries, but has heretofore not been sufficiently stable for aggressive long-life applications. 24M and its partners have identified a new approach to stabilizing the lithium-metal anode, which, when combined with the inherent cost advantages of semi-solid lithium-ion technology, can realize the energy-density promise of lithium metal, safely and at low cost.

24M and team will use nano-composite organic-inorganic protective layers to enable reversible lithium metal electrodes and low-cost, high-energy batteries based on those electrodes. The team’s core innovation takes advantage of the interfaces between the polymer and inorganic components to provide the necessary dendrite-blocking ability of ceramic-based conductors while still being highly conductive and manufacturable using traditional roll-to-roll processes.

The ARPA-E IONICS program seeks to advance storage technologies by focusing on the parts of the electrochemical cell that conduct ions and concentrates on solid materials because of the potential for greatly enhanced performance and stability.