Résumé
The undeniable benefit of lithium-ion (LIB) batteries for the development of a more environmentally friendly economy was recognized by the 2019 Nobel Prize in Chemistry. However, relying only on LIBs to energy storage will put considerable strain on lithium and cobalt resources used in these batteries. Therefore, alternative battery technologies other than LIBs are desirable to satisfy our growing demand for energy. Magnesium-ion batteries offer many distinct advantages over LIBs, including the high earth-abundance of magnesium, its high energy density and reversible dendrite-free deposition
1
. Organic materials are receiving an increasing amount of attention as electrode materials for future post lithium-ion batteries due to their versatility and sustainability
2
. In order to propose organic cathode with both high potential and specific capacity, new polymer based on hydroquinone sulfide, poly(benzoquinone disulfide) (PBQDS), were prepared in order to apply in both lithium and magnesium batteries. Diglyme and sulfolane with both LiTFSI and Mg(TFSI)
2
were selected in order to evaluate the entire potentiality of the active material
3
. First of all, the electrochemical responses of PBQDS in lithium and magnesium based electrolytes was performed in a cavity electrode. The shapes of the cyclic voltammetry curves (Figure 1) are very close in term of potential and ΔE
peak
in both lithium and magnesium systems at a relative high scan rate i.e. 1 mV s
-1
. An improvement of the redox couple reversibility seems to be observe in Mg form, with a ΔE
peak
= 400 mV at a potential of 0.3 V vs Fc
+
/Fc (near 3.5 vs Li
+
/Li). Promising first results were obtained with PBQDS using glyme + LiTFSI electrolyte, in a coin cell configuration, indeed a stable capacity of 160 mAh g
-1
was obtained at C/10 after 70 cycles, whereas 120 mAh g
-1
was obtained at C in glyme based electrolyte. In order to improve, the electrochemical performances, especially at high C-rate, the particle size was reduced by controlled grinding. The effect of the PBQDS particle size on the electrochemical performances was under process. The electrochemical investigations in both Mg and Li based electrolytes will be presented in regard to the electrolyte nature and the PBQDS morphology.
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Figure 1