1,2,4,5-Tetramethoxybenzene as a redox shuttle and their analogues in Li-ion batteries

Five different analogues of 1,2,4,5-tetramethoxybenzene were prepared and characterised for their potential use in Li-ion batteries. The samples constitute two pairs of substituted redox quinone/hydroquinone samples and a 1,2,4,5-tetramethoxybenzene sample. More specifically, the first pair was 2,5-hydroxy-substituted (non-methylated) quinone whereas the second one was 2,5-methoxy-substituted (double methylated). The quinonic structures showed a better electrochemical stability in Li-ion environment compared to the hydroquinonic structures that showed large irreversible consumption of charge during the first oxidation. Double methylation of quinone led to organic molecules with electrochemical activity at lower potential. Although non-methylated and double methylated quinonic molecules can reversibly exchange two electrons, the observed capacity was lower and only the double methylated sample showed a two-plateaux behaviour. The 1,2,4,5-tetramethoxybenzene sample that showed a formation of radical cation at a potential of 3.6 V versus metallic lithium was tested as a shuttle molecule in a combination with a LiFePO4 cathode material. The results indicate that this molecule can probably effectively prevent overcharging of batteries based on the LiFePO4 cathode material.

► 1,2,4,5-tetramethoxybenzene derivatives as electrode material for Li-ion batteries.
► Quinonic structures showed a better electrochemistry compared to hydroquinonic.
► Double methylation results in a lower electrochemical potential.
► Redox shuttle at a potential of 3.6V versus metallic lithium.