Continuous Processing of Solid-State Batteries

Identifying Challenges of Mixing Solid-State Battery Materials

Working with solid state battery blends, like liquid electrolyte applications, presents its own unique set of challenges.  When mixing a typical LIB slurry with liquid electrolyte, the electrolyte can be imparted into the active materials much easier than dry processing.  When using solid electrolyte, it takes a specialized process to disperse the powders and binders without leaving voids.  These voids can cause increased ionic tortuosity, which adversely affects the performance of the battery.  The pathways for the ions to pass between the electrodes are compromised by this occurrence.  Readco’s Continuous Processor is suited very well to provide excellent results in this environment. 

Machine Capabilities Needed for SSB Mixing

When looking at continuous processing for SSB electrode mixing we are working with two main methods of processing, which are binder fibrillation and extrusion.  These processes demand certain performance criteria from a continuous mixer.  Some of the crucial capabilities necessary are precise shear control over a broad range of intensity, excellent dispersion at low or high shear, temperature control during mixing, precise shaft speed control, short heat history with minimal necessary residence time, and the ability to do all of this without imparting residual metal into the material. 

Identifying SSB Mixing Methods

 Fibrillation of PTFE can be tricky but the ability to control the parameters makes this a bit less daunting.  There are many other binders being used or tested in the industry as well.  It comes down to the ability to manage the inputs to achieve the desired results.  Extrusion is an interesting method of producing SSB materials.  Extruders can perform many of the parameters for mixing SSB materials very well.  They are capable of heat control, high viscosity management and shear.  There are, however, some drawbacks to using an extruder for this process.  Inherently extruders use a long L/D to achieve complete dispersion.  They also generally use the materials they are mixing to keep the elements from contacting the barrel walls.  These factors can lead to longer than optimal residence times and exacerbated metal entrainment due to metal-to-metal contact. 

A Better Solution for SSB Mixing

Twin screw continuous mixers like our Readco Continuous Processor go about the job a bit differently and check the SSB processing demands boxes.  The Readco Continuous Processor (CP) has finite control over shear with a practically unlimited number of mixing element configurations. Gentle kneading to extremely high shear is attainable.  High viscosities are not a problem either with 2,000,000 Cp considered medium work.  Another attribute of the Readco CP is excellent dispersion at low shear.  An example of this is the ability to completely blend carbon nano tubes into other powders without damaging the tube’s structure.  The CP has an ASME certified jacketed barrel for heating and cooling.  Shaft speeds of 10 to 400 RPM are possible for the CP.  The CP trades time for intensity, thoroughly dispersing and mixing in a short L/D and residence time.  To top it all off, the CP shafts are supported on both ends so no metal-to-metal contact occurs and can be designed with coatings or alternative materials to eliminate metal entrainment while mixing.  So, you have all this capability along with excellent scalability.  After all, you are in business to be profitable and need maximum efficiency with uncompromised quality.  That is why we exist, to bring that type of value to your business. 

Proof of Concept  

Readco takes the risk out of going continuous by working side by side with the customer to develop your process in our laboratory located in York, PA.  Lab testing at Readco is a very collaborative process.  We create a pilot plant scenario with feeders, pumps, and one of our versatile laboratory prepped 2” or 5” Continuous Processors.  The customer leaves with proof of concept, and a detailed lab test report containing all the data needed to recreate the process in their plant.  Testing can also be conducted at the customer’s site utilizing one of our rental units, and support from the experienced Readco lab team.  

Contact Readco Kurimoto for your Battery Mixing Needs

Hopefully this information helped to bring into focus the capabilities of the Readco Continuous Processor, particularly in the SSB realm.  We look forward to the opportunity to help you with your battery processing needs.  Thank you for taking the time to read this!