POLY(Amidoamine) Dendrimer-Induced 3D Crosslinked Network Binder For LiFePO4 Cathode: Endowing Battery With Superior Cycling Stability

Abstract

The electronic and ionic conductivity inside electrode play a decision role in cell performance of lithium-ion batteries (LIBs). However, traditional polymer binder connecting the conductive network for active material often tends to lose its original structure and function after the immersion of electrolyte. This will make the conductive network collapse, thus affecting charge/discharge capacity and cycle stability of LIBs. Therefore, in this paper, Poly(amidoamine) (PAMAM) induced three-dimensional (3D) crosslinked polymer was designed and applied as binder for LIBs cathode. Compared with conventional linear Polyvinylidene fluoride (PVDF) binder, the 3D binder exhibits better bonding ability and electrolyte affinity, which respectively bring superior electronic and ionic conductivity for LiFePO4 cathode. So that the slighter polarization and better C-rate capability (140 mAh g−1 in 2C discharge) are achieved. In addition, the crosslinked network constructed in binder provides smooth and stable surficial morphology for electrode through stronger own strength and adhesion with substrate (average 7.69 N), which finally leads to improved cycling performance (98% retention after 250 cycles). Clearly, this 3D crosslinked polymer will bring new breakthrough for binder during the development of higher power LIBs.