Picture credits: Prologium
By Vikram Pol, Operations manager at Batteryline.com
A solid-state battery (SSB) is a type of battery that replaces the traditional liquid electrolyte with a solid conductor, such as a ceramic or polymer material. This design improvement offers enhanced safety, energy density, Ionic conductivity, and charging speed compared to traditional lithium-ion batteries.
Key Differences in Manufacturing Processes
Electrolyte Preparation
- Lithium-Ion: The process involves creating a liquid electrolyte solution by dissolving lithium salts (LiPF6) in an organic solvent (Dimethyl Carbonate (DMC), Diethyl Carbonate (DEC), and Ethyl Methyl Carbonate (EMC)). This solution must be carefully handled to maintain purity and prevent contamination.
- Solid-State: The solid electrolyte is either synthesized as a powder and then formed into a film through processes like sintering (ceramics) or cast from a polymer solution. This process requires precise control over material composition and structure to ensure ionic conductivity.
Popular materials for SSB electrolytes include lithium lanthanum zirconium oxide (LLZO), lithium argyrodite (LAG), and polyethylene oxide (PEO).
Mixing and Electrode Fabrication or manufacturing
Slurry Mixing: For some solid-state battery designs, especially those incorporating polymer-based solid electrolytes, a slurry of electrode material might be prepared. This slurry could include a binder and conductive additives, similar to the process for lithium-ion batteries, but using a solvent that is compatible with the solid electrolyte.
Coating and Drying: The slurry can be coated onto a current collector and then dried, a process similar to that used in traditional battery manufacturing but adapted for the thermal and chemical sensitivity of the solid components.
- Lithium-Ion: Electrodes are typically made by coating a slurry containing active materials, conductive additives, and a binder onto a metal foil (copper for anodes, aluminum for cathodes). The coated foil is then dried and compressed.
- Solid-State: Electrode fabrication can be similar, but the compatibility of the electrode with the solid electrolyte is crucial. Often, additional steps are needed to ensure that the interfaces between the electrodes and the solid electrolyte are stable and conductive.
Cell Assembly

- Lithium-Ion: Assembly involves stacking or winding the coated electrodes separated by a liquid-permeable separator soaked in electrolyte. The assembly must be done in a dry environment to prevent moisture from reacting with the electrolyte.
- Solid-State: This process involves layering electrodes and solid electrolyte layers, often requiring lamination or a compression step to enhance contact. No liquid or gel separators are needed, which simplifies some aspects of assembly but introduces challenges in ensuring perfect layer interfaces.
Formation and Conditioning
- Lithium-Ion: Once assembled, Li-ion batteries undergo a formation process where they are charged and discharged several times to form a stable solid electrolyte interphase (SEI) on the anode. This step is crucial for battery longevity and performance.
- Solid-State: Formation processes in SSBs also involve charging and discharging, but the focus is more on ensuring that the solid electrolyte and electrodes are well-integrated. The absence of a liquid electrolyte means there is no need to form an SEI, but interface stability remains a challenge.
Scaling and Quality Control
- Lithium-Ion: Scalability of Li-ion technology is well-established, with extensive automation and quality control processes in place to ensure consistency and safety.
- Solid-State: Scaling SSB manufacturing is still under development, with ongoing research focusing on automating the layering process and improving the consistency and quality of solid electrolytes.
Conclusion
Solid-state batteries (SSBs) modify several core aspects of traditional lithium-ion battery manufacturing by eliminating the liquid electrolyte and porous separator, and often replacing graphite anodes with lithium metal foils. These changes enhance energy density and safety by reducing flammable components and potentially improve ionic conductivity. However, the transition to SSBs introduces manufacturing challenges due to the need for specialized equipment and techniques to handle solid materials effectively.
Despite their promising advantages, scaling up SSB production remains complex and costly, requiring substantial advancements in technology and manufacturing processes. Overcoming these challenges is essential for the wider adoption of SSBs, particularly in sectors demanding higher safety and efficiency, like electric vehicles and portable electronics.
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