Next-Generation Solid-State Lithium-Sulfur Battery Portfolio (SABERS 2.0)

Battery cells are sealed inside a strong, flexible pouch which is placed inside a lightweight pressure vessel filled with inert working fluid (e.g., argon gas, silicone oil) that applies a low pressure evenly around the pouch, ensuring uniform compression and eliminating directional stress on the cell. This case maintains constant pressure throughout the battery’s life cycle to ensure consistent contact between solid components, which optimizes performance and minimizes damage. The pressure necessary in this design is much lower than that in uniaxial systems, which allows for a less heavy packaging system. This lightweight design and improved technique may show particular relevance on large scales (e.g., aerospace, automotive), where onboard load weight and longevity are priorities. This isostatic battery case contributes to the SABERS 2.0 portfolio (LEW-TOPS-188), improving the state of the art for solid-state batteries. Currently at a TRL 4, the case is available to license independently or as part of the larger SABERS solid-state battery suite.

The SABERS innovators developed novel lithium-sulfur designs, including sulfur-selenium on graphene cathodes, and lightweight bipolar plate stacking and packaging designs. SABERS is unique in several aspects, in particular, it deploys graphene-based manufacturing processes for the cathode and bipolar plates, and it uses a solid-state electrolyte in place of the liquid electrolyte found in other lithium-sulfur battery designs. The team has achieved energy densities over 500 W-hr/kg, with ongoing development targeting further improvements. Coin cell and pouch prototype demonstrations have been successful and are ongoing. Major component technologies in SABERS include the following: • S/Se Cathode – Sulfur/Selenium on graphene scaffold (LEW-20228-1) • Solid Electrolyte – Solid-state electrolyte composites (LEW-20445-1) • Bipolar Stack – Graphene plates (LAR-20257-1) Robust computational models have been developed to support the battery materials design and are available to licensees to evaluate and optimize different materials combinations and performance targets. Further developments in catholyte formulations, anode interlayering, and packaging optimization are presented in SABERS 2.0 (LEW-TOPS-188). Individual technologies can be licensed from either suite, or entire portfolios can be licensed to support solid-state battery development programs.

The first technique improves electrolyte densification, which is essential for ion conductivity and battery reliability overall. The process involves the use of a sintering aid (e.g., sulfur) to achieve denser and more stable electrolytes than are achievable through more common, high-temperature processes. Electrolytes that are denser and less porous have higher ion conductivity (thus better performance), longer cycle lives, and lower volatility. Aside from densification, this technique also significantly increased the base electrolyte's lithium wettability. The second innovation is a new cathode and electrolyte design using a mixed conducting material that can carry both ions and electrons, which simplifies the cathode’s composition by eliminating the need for separate ion and electron conductors. This catholyte is a composite that utilizes a mixed conducting material, replacing both the ion and electron conductors with a single material thus simplifying solid state cathode design from a 3-component to 2-component composite. The mixed material is composed of a metal chalcogenide, such as titanium disulfide (TiS2), which can act as a mixed conductor and contributes to energy storage. The addition of sulfur boosts energy capacity up to 33% compared to traditional cathode designs. Reducing single-conduction phases simplifies energy transport pathways and improves efficiency, making solid-state batteries easier to produce and safer to use. These two innovations work together to improve the state of the art, creating solid-state batteries with higher temperature tolerances and up to five times more energy capacity than current lithium-ion batteries. They stand together at a TRL 4 and are available for patent licensing individually or as part of the larger SABERS (LEW-TOPS-167) or SABERS 2.0 portfolio (LEW-TOPS-188).

The subject technology is an extension of closely related, solid-state ultracapacitor innovations by the same team of inventors. The primary distinction for this specific technology is the addition of co-dopants to affect the dielectric behavior of the barium titanatebased perovskite materials. These co-dopants include lanthanum and other rare earths as well as hydroxyl ions. The materials are processed at the nano scale, and are subjected to carefully designed thermal treatments as well. The presence of the hydroxyl ions has been shown to provide several orders of magnitude increase in the capacitance of the dielectric material. Additionally, these high capacitance values are obtained at relatively low voltages found in current consumer and industrial electronics. The capacitors tested to date are simple, single-layer devices. Ultimately, a range of manufacturing methods are possible for making commercial devices. Features of the technology enable manufacturing via traditional thick-film processing methods widely used in the capacitor industry, or via advanced printing methods for state-of-the-art printed electronics. Future efforts will be made to advance the manufacturing and packaging processes to increase device energy density, including multilayer devices and packages

In traditional batteries with liquid electrolytes, e.g., lithium-ion, each battery cell must be individually sealed, packaged, and electrically connected to other cells in the pack. The cells in solid-state batteries on the other hand may be stacked on top of one another with only a separation layer in between, called a bipolar plate. These bipolar plates or membranes if thin enough must be electrochemically inert to the electrode and electrolyte materials while providing electrical connectivity between the individual cells. Here, NASA has combined advances in the preparation of carbon nanomaterials and solid-state batteries to create extremely lightweight bipolar plates and membranes. These bipolar membranes will enable high energy density solid-state batteries unachievable with typical bipolar plate materials like stainless steel, aluminum, aluminum-copper, or conductive ceramics. The carbon bipolar membranes may be fabricated in multiple ways including but not limited to directly compressing carbon powders onto an electrode-electrolyte stack or separately making a film of the carbon material and dry pressing the film between other battery layers. The new bipolar membranes have been demonstrated in high energy density solid-state batteries in coin and pouch cells. The carbon bipolar membranes are at technology readiness level TRL-4 (Component and or breadboard validation in laboratory environment)and are available for patent licensing.