This technology implements a cross-linked polymer binder by ionically bonding dopamine-grafted polyacrylic acid (Dopamine-PAA) with the basic polymer polyaniline (PANI). Dopamine enhances adhesion through hydrogen bonding with the silicon surface, while PANI improves both mechanical properties and electrical conductivity through ionic bonding with the carboxylic acid of PAA.
Silicon anodes suffer from electrode pulverization due to volume changes of up to 400% during charge and discharge cycles. This disrupts electron transport pathways and increases electrolyte side reactions, leading to reduced efficiency and shortened lifespan. Conventional binders like CMC and SBR have limited capacity to withstand such physical stress.
This technology is composed of a mixture of polyacrylic acid (first copolymer) grafted with dopamine segments and 10 wt% polyaniline (second copolymer), forming a cross-linked structure through ionic bonding between carboxylic acid and nitrogen. This structure enhances the mechanical durability of the electrode and silicon adhesion, thereby improving reversible capacity and cycle life. It can be applied to high-capacity lithium secondary batteries using silicon or silicon-graphite composite anodes, preventing electrode detachment during repeated expansion with a peel strength of 0.6–0.7 N.
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