Carbon Nanotube-graphene Nanoplatelet Hybrids and Their Polymer Composites as Binders for Lithium-ion Li₄Ti<sub>5</sub>O<sub>12</sub> Negative Electrodes

This paper presents a new water-based conductive binder composed of carbon nanotubes (CNTs) and graphene nanoplatelets (GnPs) for high-powered Li₄Ti₅O₁₂ (LTO) negative electrodes. A solution containing a certain amount of CNTs, GnPs, or both was used to synthesize emulsified poly(acrylonitrile-butyl acrylate) (PANBA) containing conductive CNT, GnP, or CNTxGnP1-x hybrids. These polymers were applied as binders for LTO electrodes and the electrochemical performance was compared with that of a nonconductive PANBA binder. The conductive<br/>CNT_xGnP_1-x-PANBA binders had several advantages: superior water-dispersion stability and elongation, lower transport resistance for electrons and lithium ions, and lower charge transfer resistance. This led to stable cycling capacity above 130 mAh g^-1 at the 100^th cycle for the CNT_xGnP_1-x-LTO electrodes without conducting agents and high capacity retention of 5 C/0.2 C above 58.0%. In contrast, the nonconductive PANBA-LTO electrode showed a cycling capacity of 118 mAh g^-1 at the 100^th cycle and a capacity retention of 5 C/0.2 C of 44.1%.