PTMA/Graphene as a Novel Cathode Material for Rechargeable Magnesium Batteries

Abstract

We report the synthesis of a poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA)/ graphene nanocomposite in which graphene is used as a support for improving electronic conductivity. The structure and morphology of the nanocomposite were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). These results reveal that a graphene surface is decorated by nanoparticles of PTMA with an average size of 10 nm. The electrochemical performance of the PTMA/graphene composite as a cathode material in rechargeable magnesium batteries was investigated using cyclic voltammetry and galvanostatic charge/ discharge techniques. In a"first generation"electrolyte Mg(AlCl2BuEt)2/tetrahydrofuran (THF) (0.25 mol•L -1 ), the material exhibits an initial discharge capacity of 81.2 mAh•g -1 at 22.8 mA•g -1 . Further studies will focus on improving the capacity using electrolytes with a wider electrochemical window.

Organic Positive Materials for Magnesium Batteries: A Review

“…In 2013, PTMA was tested as a cathode for Mg batteries. [126] PTMA was frequently synthesized by radical polymerize of 2,2,6,6-tetramethylpiperidine methacrylate with the presence of radical initiator like 2,2'-azobisisobutyronitrile (AIBN) and oxidation of the crude product (Scheme 15). [127] A systematic study of the post-polymerization modification of the product 2,2,6,6-tetramethylpiperidine methacrylate (PMTMP) was recently reported.…”

“…Although these compounds are stable, non-toxic, and cheap, their low specific capacity and cyclability induce a critical barrier for practical application in batteries. [126] The advantages of this material are the charge storage density and extremely fast electrode response kinetics, showing the potential to become a generation of high-power and highenergy anode material. The biggest drawback, however, is the low electrical capacity, which limits practical applications in rechargeable Mg batteries.…”

“…Studies showed that free radicals on this material can participate in the electrode reaction as electrons can rapidly pass through the material. In 2013, PTMA was tested as a cathode for Mg batteries [126] . PTMA was frequently synthesized by radical polymerize of 2,2,6,6‐tetramethylpiperidine methacrylate with the presence of radical initiator like 2,2’‐azobisisobutyronitrile (AIBN) and oxidation of the crude product (Scheme 15).…”

“…The quite low values were explained by the partial solubility of the polymer into the used electrolyte and the low compatibility between this material and the electrolyte system (Figure 15). Although these compounds are stable, non‐toxic, and cheap, their low specific capacity and cyclability induce a critical barrier for practical application in batteries [126] …”

Opportunities and Challenges in the Development of Cathode Materials for Rechargeable Mg Batteries

“…Organic materials often contain electrophilic centers inside their structures, which makes them incompatible with nucleophilic Mg electrolytes. However, there have been reports, where nucleophilic electrolytes are used with organic cathodes, but it is difficult to differentiate between electrochemical activity attributed to organic compounds and pseudocapacitance response from side reactions in this class of electrolytes (NuLi et al, 2007; Qiang et al, 2013). The first reversible electrochemical reaction of an organic compound with Mg 2+ ions was demonstrated on dimethoxybenzoquinone (DMBQ) in 0.5 M Mg(ClO 4 ) 2 in γ-butyrolactone and confirmed through ex-situ XRD (Sano et al, 2012).…”