Binders

The binder as name says its role is to bind all the electrode materials tightly to the foil and make a stable network of solids which is mechanically strong and electrochemically stable. The main components of the electrode are the active material, conductive additives and binders along with certain degree of porosity for the electrolyte to fill in it. So, the main role of binder is to bind with sufficient mechanical strength but there are other characteristics such as interface with active material and interaction with the electrolyte. 

Non-aqueous binders : These binders are not based on water, and instead use organic solvents or polymeric materials as the binding agent. The use of non-aqueous binders in lithium-ion cells has several advantages over aqueous binders (which are based on water). Non-aqueous binders are generally more stable and less reactive than aqueous binders, which means they can help to improve the safety and longevity of the cell. They are also less likely to cause side reactions with the active material in the cathode and anode, which can help to improve the performance of the cell.

One of the most commonly used non-aqueous binders in lithium-ion cells is polyvinylidene fluoride (PVDF), a synthetic polymer that is known for its high strength, flexibility, and thermal stability. PVDF is typically used in the form of a powder or slurry, which is mixed with the active material in the cathode and anode to form a cohesive structure. PVDF is used along with NMP solvent in slurry preparation which is considered as toxic.

Other commonly used non-aqueous binders in lithium-ion cells include polyacrylonitrile (PAN), polyethylene oxide (PEO), and polyethyleneimine (PEI), all of which have different properties that make them suitable for different applications. The choice of binder for a specific lithium-ion cell will depend on the specific requirements of the application, including the desired performance, safety, and compatibility with other materials used in the cell.

Aqueous binders : These binders are typically used in the form of an aqueous solution, which is mixed with the active material in the cathode and anode of the cell to form a cohesive structure.

Aqueous binders have several advantages over non-aqueous binders (which are not based on water). For example, aqueous binders are typically less expensive and easier to manufacture than non-aqueous binders. They are also less toxic and more environmentally friendly than many non-aqueous binders, which makes them a more attractive option for some applications.

One of the most commonly used aqueous binders in lithium-ion cells is polyvinyl alcohol (PVA), a synthetic polymer that is known for its high strength, flexibility, and water solubility. PVA is typically used in the form of a powder or slurry, which is mixed with the active material in the cathode and anode to form a cohesive structure.

Other commonly used aqueous binders in lithium-ion cells include carboxymethyl cellulose (CMC) and Styrene butadiene rubber (SBR).