Homology and isomerism effect of aromatic imides as organic anode materials of lithium-ion batteries

Organic materials have been promising materials for “greener and sustainable” lithium-ion batteries due to lightweight, low cost, flexibility, alternative molecular engineering. Six kinds of aromatic imides with different aromatic and aliphatic diamines based on 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) were designed, synthesized and studied as anode materials in rechargeable lithium-ion batteries in this work. Compared with ortho-substituted and meta-substituted phenylenediamine, aromatic imide synthesized by p-phenylenediamine shows excellent electrochemical performance on account of its well-organized structure, which possesses 558 mA h g−1 of discharge capacity after 50 cycles at the current density of 25 mA g−1. Besides, imides with shorter alkyl chain would help improve the proportion of electrochemical active conjugated carbonyl compounds, leading to higher capacity. Thus, imide-based electrode materials can be designed efficiently by symmetrical and straight chain structure and less inactive part to gain optimum molecular structure, making it a promising alternative anode material for rechargeable lithium-ion batteries.