Reasons for using oil-based binders for positive electrode slurry:

Chemical stability: Oil based binders such as polyvinylidene fluoride (PVDF) have a wide electrochemical stability window, with stable electrochemical performance in the range of 0-5V (Li/Li+), able to withstand high voltage environments, and avoid oxidation under positive electrode high voltage conditions.

Mechanical properties: Oil based binders exhibit good dispersibility and density in high-density positive electrode materials, preventing slurry settling and uneven distribution of active materials, thereby improving the structural stability of electrode sheets.

Environmental friendliness: Oil based systems can effectively prevent battery swelling caused by water introduction, reduce damage to positive electrode materials, especially for high nickel materials, and prevent lithium leaching and slurry pH increase.

Processing performance: Oil based binders such as PVDF have good compatibility with positive electrode materials, and their dispersibility during slurry preparation ensures the uniformity of the slurry and the density of the electrode sheets.

Cost effectiveness: Although the recycling and processing costs of oil-based binders are relatively high, the overall cost is within an acceptable range due to their widespread application in positive electrode materials and mature production processes.

Reasons for using water-based binders for negative electrode slurries:

Cost and environmental protection: water-based binders such as carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) lotion have low cost and environmental protection, avoiding the use of organic solvents and possible environmental pollution.

Processing performance: Water based binders are easy to mix evenly with negative electrode materials such as graphite, improving the dispersion of the slurry and reducing the collapse and powder loss of the electrode sheet during compression and cutting processes.

Bonding and Flexibility: The combination of CMC and SBR not only provides good bonding strength, but also enhances the flexibility of the electrode, adapting to the volume changes of the negative electrode material during charging and discharging processes.

Cycle performance: Water based binders help improve the cycle and rate performance of batteries, although in some aspects such as initial discharge capacity may be slightly lower than oil-based binders, they perform more stably in long-term cycles.

Interface impedance: The electrode interface impedance formed by water-based adhesive is relatively low, which helps to reduce the internal resistance of the battery and improve the charging and discharging efficiency.

In summary, the use of oil-based binders for positive electrode slurries is due to their advantages in chemical stability, mechanical properties, and processing technology, while the use of water-based binders for negative electrode slurries is based on considerations of cost-effectiveness, environmental protection, and processing performance.