Triazole-enabled small TEMPO cathodes for lithium-organic batteries

The use of redox-active organic compounds to make rechargeable batteries is a promising strategy for future energy storage especially from a resource and environmental sustainability point of view. While many organic structures have been identified as potential electroactive materials, their direct application in solid-state energy storage is limited. This is due to their high solubility in common organic electrolytes, resulting in poor long-term battery performance. In this work, we overcome this significant problem by synthesizing very low soluble nitroxide radicals with theoretical capacities of 111–131 mAh g⁻¹, equal to or higher than most commonly used nitroxide radical polymers. These new structures consist of TEMPO (i.e. 2,2,6,6-tetramethylpiperidinyl-1-oxy) radicals and triazole ring linkages synthesized by the copper-catalyzed azide-alkyne cycloaddition (CuAAC) ‘click’ reaction. Analysis of electrode morphology and electrochemical performance at increasing mass loading of the nitroxide radicals demonstrate the importance of lower solubility, preventing the shuttle effect observed for common organic electrode materials. The electrodes with the content of active materials up to 80 wt% can still maintain a good interaction with the carbon and conductivity throughout the electrode and deliver a capacity greater than 60 mAh g⁻¹ over 200 cycles.