(A-)폴리아크릴산(A=H, Li, Na and K)을 도입한 CMC/SBR 바인더시스템 리튬이차전지 흑연 음극의 특성과 성능에 관한 연구

Abstract

Lithium-ion batteries (LIBs) have attracted attention as energy storage devices, owing to their advantages such as high energy density and excellent cycle performance. Recently, with an increasing demand for more compact electronic devices, there has been an especial interest in designing high volumetric energy density LIBs with thick and high density anode with conventional active materials such as graphite. However, the thick and high density graphite anode exhibits low lithium ion diffusivity due to significant decrease of both pore size and pore volume. The thick and high density graphite electrode with low porosity results in poor electrolyte permeability into the electrode eventually affects poor electrochemical performances. In this study, Poly(acrylic acid) and alkali metal ion substituted poly acrylate with simple synthesis (A-PAA, A = H, Li, Na and K) have been prepared as binders to improve electrolyte permeability in high density/thick graphite electrode. With introducing A-PAAs, electrolyte permeation rate has been greatly enhanced at least 69 % for their high-electrolyte uptake property due to abundant carboxylate functional group on the polymer structure. Meanwhile, adhesion strength doesn’t satisfy the minimum required value 1.0 gf/mm except H-PAA. In particular, the adhesion strength for H-PAA introduced electrode shows 2.7 gf/mm which is 2 times greater than that of reference electrode due to the abundant carboxylic acid -COOH groups of H-PAA. Furthermore, H-PAA introduced electrode shows the best battery performance in both rate capability at 1 C and cycle retention at 35th cycle with moderate swelling behavior.