Polyacrylonitrile-based rubber (HNBR) as a new potential elastomeric binder for lithium-ion battery electrodes

A commercial elastomer, Hydrogenated Nitrile Butadiene Rubber (HNBR), is used as a binder for Li-ion battery positive and negative electrodes. As the polymer as never been used before as a binder, the aim of this study is to investigate the chemical stability of HNBR with regard to the electrolyte, to show its electrochemical stability, and to demonstrate the application of these elastomers in Li-ion battery electrodes. To ensure insolubility in the electrolyte, HNBR is previously crosslinked and tensile tests are used on these films to evaluate their mechanical properties. The electrochemical stability of this polymer is analysed and validated by cyclic voltammetry. Power and cycling performances of crosslinked HNBR-based electrodes are compared to conventional ones using poly(vinylidene fluoride) (PVdF). It is found that crosslinked HNBR is electrochemically stable in the potential windows studied, i.e. 1–2.2 V and 2.2–4.2 V. When used in positive and negative electrodes, crosslinked HNBR full-cell retains a capacity of 128 mAh.g−1 after 200 cycles, compared to 117 mAh.g−1 for conventional PVdF cells. This makes HNBR a good candidate as a binder for Li-ion batteries.