Carbon Bipolar Membranes for Solid-State Batteries

Power Generation and Storage

Carbon Bipolar Membranes for Solid-State Batteries (LAR-TOPS-375)

Lightweight Separation Layers for High-Performance Next-Gen Batteries

Overview

Innovators from the NASA Langley and NASA Glenn Research Centers have developed materials and processes to use carbon nanomaterials as bipolar membranes or plates for separating solid-state battery unit cells. Using carbon materials over current bipolar plates will be an enabling technology for lightweight, high energy density solid-state batteries. Bipolar membranes or plates provide a chemically inert but electrically conductive layer separating solid-state battery unit cells that allow them to be stacked within a single package. Here, the developed bipolar plate materials include films or membranes of graphene, holey graphene, and carbon nanotubes. These carbon materials provide a significant weight savings over currently used metallic materials while maintaining the necessary performance characteristics of the bipolar plates. These new bipolar membranes or plates may be employed in high energy density solid-state batteries for electrified aircraft, electric vehicles, or a variety of electric devices that require high performance batteries.

The Technology

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.

(Left) Schematic of a tri-layer bipolar solid-state battery with a holey graphene (hG) bipolar membrane. (Right) Discharge and charge voltage profiles of a dual-layer bipolar solid-state lithium-sulfur battery ("Dual") with a hG bipolar membrane, in comparison to one with a stainless steel (SS) bipolar plate and a single-layer lithium-sulfur battery ("Mono").

Benefits

Reduced packaging weight: carbon nanomaterials (e.g., graphene, holey graphene, or carbon nanotubes) are significantly lighter than currently used metals or ceramics.
Simpler battery design: Moving to stacked solid-state batteries enables significantly simpler battery packaging and design compared to liquid electrolyte batteries.
Wide compatibility with battery chemistries: the carbon nanomaterials will be electrochemically inert to most if not all current and future solid-state battery chemistries.
Improved adhesion to battery layers: carbon nanomaterials provide superior adhesion and electrical contact to the active battery layers over the metallic materials commonly used as bipolar plates.

Applications

High energy density solid-state batteries: the carbon bipolar plates can provide electrochemical isolation for stacked solid-state batteries with various chemistries.

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Technology Details

Category Power Generation and Storage

Reference Number LAR-TOPS-375

Case Number(s) LAR-20257-1

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