Polymer Binder for Secondary Batteries and Manufacturing Method Thereof

Silicon Nanoparticle Anode Binder Using PAAA Conductive Polymer Copolymerized with Anthranilic Acid

This technology features a conductive polymer binder that enhances binding strength with silicon nanoparticles by copolymerizing anthranilic acid, which contains polar functional groups (-COOH), into an aniline backbone. It effectively accommodates the volume expansion of silicon anodes.

Silicon anode active materials suffer from electrode detachment due to rapid volume changes of 300–400% during charge and discharge cycles. Conventional binders like PVdF lack sufficient physical interaction with silicon, leading to rapid degradation in battery life and efficiency.

This technology utilizes a PAAA (Poly(aniline-co-anthranilic acid)) copolymer, synthesized with a molar ratio of aniline to anthranilic acid between 0.45:0.55 and 0.55:0.45, as a binder. The -COOH functional groups form hydrogen bonds with the silicon surface (SiO2, Si-OH) and the current collector, strengthening adhesion and increasing lithium-ion conductivity to mitigate mechanical stress from volume expansion. Applicable to high-capacity lithium secondary batteries using silicon nanoparticle anodes and conductive binder material businesses, the simple polymerization process, completed within hours at room temperature, also reduces material production costs.

‍

‍

Key Features:

• A step of adding an initiator to a solution containing aniline and anthranilic acid monomers mixed in a molar ratio of 0.45:0.55 to 0.55:0.45 and allowing them to react
• A step of reacting the mixed solution containing an ammonium persulfate initiator at room temperature for 2 to 4 hours, followed by filtering the product with acetone
• A step of adding and mixing silicon nanoparticle anode active material into the prepared polymer binder solution
• A step of coating the mixture onto a metal foil, drying it at 70 to 90 °C to manufacture an electrode, and assembling the cell

‍