All-Solid-State Batteries

The All-Solid-State battery (ASSB) is considered a disruptive concept which increases the safety, performance and energy density compared to current lithium-ion battery cell technologies. By eliminating the need for liquid electrolyte, it also allows the implementation of completely new cell concept ideas and integration strategies.

The research activities in the field of ASSB at Fraunhofer ISE range from the development of tailor-made electrode materials and manufacturing of battery cell components (separator and electrodes) to the assembly of the complete battery cell.

Based on our experience and techno-economic evaluations in the field of lithium-ion storage systems, we decided to focus mainly on the use of sulfide electrolytes in ASSB. This class of materials allows high lithium-ion conductivities at room temperature (10^-3-10^-2 S∙cm^-1) without the need for an additional liquid electrolyte. Similar to polymer solid electrolytes, sulfide electrolytes also combine the material properties required for industrial processing with a low crystalline density, allowing high energy densities (> 400 Wh∙kg-1 / > 1000 Wh∙l-1)  to be achieved by using conventional cathode materials (e.g. NMC-based materials such as LiNi_0.8Mn_0.1Co_0.1O₂).

Our R&D-Services on the Topic "All-Solid-State Batteries" Include:

• Tailored Active Materials for All-Solid-State-Batteries
• Manufacturing of Electrodes and Separators
• Cell Assembly and Characterization of All-Solid-State-Batteries
• Development of Demonstrator and Production Technology Validation for ASSB Concepts

Active materials are an essential component of every battery cell. Here at Fraunhofer ISE, we are taking a deep dive into the synthesis and refinement of novel and sustainable active materials. Thereby, we mainly concentrate on customizing the material to suit the ASSB cell's requirements.

Our R&D offerings in the area of “Tailored Active Materials for All-Solid-State-Batteries” include:

• Refinement of active materials by pre-lithiation and/or surface coating
• Development and scaling of tailored energy dense active materials (e.g., cobalt-free NMC-like materials and their Li-rich versions)
• Blending of active material and solid electrolyte using our established milling procedure (or adjusted to customer request) at different scale
• Characterization of materials using in‑house measuring instruments

At Fraunhofer ISE, we are dedicated to two strategic methods for the manufacturing of ASSB. The production of individual components (cathode, separator and anode) for the self-standing design, allows us to resemble the established process for the production of lithium-ion batteries and thereby investigate the possibility of a drop-in replacement for an accelerated introduction of this technology to the market. In the 2-component design, however, the separator is applied directly on top of an electrode, enabling the production of ultra-thin separators (< 15 µm).

Our R&D offerings in the area of “Manufacturing of Electrodes and Separators” include:

• Supply of in‑house manufactured electrodes (NMC cathode, Si anode) with an areal loading of 0.5 – 4 mAh·cm^-2 for external investigation. Composition (active material, solid‑electrolyte and additives) of all electrodes can be adjusted by customer request.
  
• Production of solid-state separators (20 – 50 µm) for external investigation using our in‑house developed infiltration process for scaffold-supported self-standing products or our bilayer casted design on top of an electrode (cathode or anode).  
• Design of slurry recipes (liter-scale) for the production of ASSB-electrodes and separators. 

Details play a crucial role. Here at Fraunhofer ISE, we are taking a close look on the life of an ASSB cell. From the microstructural changes after joining the components to the performance testing of the cell and until its end-of-life. Each individual step can be investigated in our facilities.

Our R&D offerings in the area of “Cell Assembly and Characterization of All-Solid-State-Batteries” include:

• Testing of ASSB cell components / materials in different cell formats (coin, pressure and pouch cells)
• Investigation of manufacturing parameters (temperature, pressure and atmosphere) during ASSB cells assembly
• Electrochemical analysis (cycling stability, performance testing and cell impedance)
• In operando analysis of pressure and/or temperature dependencies
• Post-mortem analysis (e.g., microstructural analysis of battery cell cross-section)

ASSB are on the horizon of industrial production. Our dry room facility and pouch cell pilot line enable us to assemble and investigate ASSB in commercial relevant formats. 

Our R&D offerings in the area of “Development of Demonstrator and Production Technology Validation for ASSB Concepts” include:

• Technical evaluation of cell chemistry and production processes for solid-state batteries
• Production of single/multi-layer pouch cells with components according to customer requirements
• Provision of single/multi-layer pouch cells with ISE's own components for external investigations
• Support in development projects for the integration of solid-state batteries