Designing customized anode and cathode materials and solid electrolytes by Glatt powder synthesis
Do you want to advance battery technology with new or improved raw materials? Commercial raw materials do not meet your expectations in terms of capacity and long-term stability? Or do you have a promising material approach that only works on a laboratory scale?
The high flexibility of this technology and the special conditions in the pulsating hot gas stream let you produce active materials and solid electrolytes in just one process step.
To produce a homogeneous powder e.g. a cathode material or solid electrolyte, a solution of the raw materials in the desired stoichiometry is made. This approach allows even the smallest amounts of doping elements to be homogeneously incorporated into your final product after the drying and formation process within the pulsating gas stream. Hereby, performance characteristics such as capacity and charging behavior of modern battery materials can be influenced in a quality-enhancing manner. The particularly high heat and mass transfer rates of this process can also be used to calcine powders to achieve the desired crystalline structure. The formation of hard aggregates will be prevented by the pulsating hot gas stream.
For protection of anode or cathode materials against aggressive electrolytes, the surface of the particles of your material can be refined by a coating. For such a core-shell coating, the coating material is dissolved in a suspension, sprayed and dried. Process temperatures in the range between room temperature and 1300 °C offer an almost inexhaustible choice of core-shell combinations.
Refining battery raw materials by Glatt fluid bed technology
Do you have issues with the homogeneity of your battery raw materials? Is the processability of materials you are using right now constrained by segregation, dust formation or poor pourability?
To improve the processability of powder mixtures, spray agglomeration in the fluid bed can counteract segregation in subsequent processes, packaging or transport. By spraying on a binder solution, the surface of the mixture is wetted and fine particles agglomerate into larger granules or are adhered to coarser particles. However, if the shape and size are too different, fine particles can alternatively be sprayed on together with the binder solution and thus be homogeneously distributed over the coarser components. Homogeneity and pourability of your raw materials will be improved, dust formation prevented.
But fluid bed technology does offer additional options that will help you to optimize your raw materials or their precursors to create exactly the material, you need for your application. Based on the setup and process parameters you can use the same technology either for spray drying or to bring a functional or protective layer on your powder material. Spray granulation can be used to create pourable, compact and stable precursor granules out of suspensions. These granules can be later heat treated in a kiln, or – utilizing its better heat and mass transfer rates – in a high temperature fluid bed system.
Develop and test your material in the Glatt Technology Center in Weimar
At the Glatt Technology Center in Weimar, we work with you to determine the optimum process conditions for your product in feasibility trials for product development. Various laboratory facilities and comprehensive analytical equipment are available for this purpose. On our pilot plants, we optimize the process and scale it up reliably to a stable and economical production scale. The results from this form the basis for the design and construction as well as the erection of your fluid bed or spouted bed plant, tailored to your requirements. As an alternative to our own process technology, we offer you the outsourcing of your production by means of contract manufacturing at Glatt.
Case study: Cathode material
The cathode takes up almost half of the battery’s volume and drives up its price. Therefore, the development of cost-effective, highly efficient and durable materials is of utmost importance.
The structure of lithium manganese nickel oxide, LMNO / spinel powder can be easily modified by the synthesis parameters. The stoichiometry allows easy adjustment of the powder properties.
The way to mass production of lithium nickel manganese oxide, LNMO at low cost leads to Glatt powder synthesis. Due to the special conditions prevailing in the synthesis reactor, targeted structures can be generated and optimized. Next generation materials can be synthesized, modified and also produced continuously in larger quantities using this technology.
The particle size and crystal structure can be specifically influenced by the plant parameters temperature, vibration frequency and amplitude. In feasibility studies, very fine particles (smaller than 5 µm) with the characteristic octahedron structures have already been generated. Targeted dopants can also be generated easily. These enable a further increase in capacity and improve efficiency for fast charging and discharging. The synthesis of cathode materials such as LNMO is carried out in one process step and is based on inexpensive raw materials. This makes up-scaling and thus future large-scale use possible in the first place.
Carbon-silicon anode material produced by Glatt powder synthesis
Case study: Silicon-based anode material
Carbon-based anodes have dominated the market in the past. However, the drive for higher capacities is increasingly forcing manufacturers to find alternative solutions. Silicon in particular is predestined for this application due to its good availability and high specific capacity (Li15Si4 3600 mAh/g vs. LiC6 372 mAh/g) . However, the technical challenge with silicon is the volume change that occurs (Li15Si4 320% vs LiC6 10%) during the charge/discharge cycle , which in the long run leads to fracture of the particles, loss of contact to the current sink and continuous erosion of the protective boundary layer between silicon and electrolyte.
 A. Mukhopadhyay et al. Deformation and stress in electrode materials for Li-ion batteries; Progress in Materials Science, 63, 2014, 58-116.
A promising approach is therefore the use of silicon-carbon composite materials: the carbon compensates for the volume change of the silicon and protects it as an elastic layer from direct contact with the electrolyte. Silicon particles, dissolved organic binder and, if necessary, other additives are prepared in a suspension and sprayed in the synthesis reactor. Depending on the process control, the silicon particles can be agglomerated or wet the particles as a solute and form a layer during drying. If required, the binder or layer phase can also be pyrolyzed in the same process step via an appropriate temperature regime.
New battery materials by Powder Synthesis: sintered LLZO membrane
Case study: Solid oxide electrolytes
The trend in batteries is increasingly toward solid-state batteries. The most difficult part of this is developing a solid electrolyte that can compete with the ionic conduction of liquid electrolytes. Two main concepts are currently being pursued for this, involving either oxide or sulfide ionic conductors.
Glatt powder synthesis is used in various projects for the development of solid oxide electrolytes, especially lithium lanthanum zirconium oxide, LLZO, and doped variants thereof. The primary goal is to investigate the simplification of synthesis, the reduction of manufacturing costs and the development of an effective concept for up-scaling.
As a result, LLZO solutions based on low-cost raw materials were implemented using powder synthesis. The adjustment of particle size, bulk density and crystal structure was achieved by adjusting various parameters. Further processability of the powders into ceramic films was also demonstrated. Conventional processes for the production of LLZO are usually in the gram or kilogram range. The advantage of the described technology is that the process can be easily scaled up to production scales.
Case study: Coated cathode materials to increase long-term stability
In service, cathode materials are subject to constant attack by the electrolyte. A novel approach to this is to coat the cathode materials to protect them from dissolution or other undesirable reactions when in contact with liquid or solid electrolytes.
EDX mapping of a Li3PO4 coating on NMC 622 using the tracer elements phosphorus (coating) and manganese (core)
Further information on applications of Glatt powder synthesis can also be found in the following publications: