Spontaneous electrochemical stabilization of nanostructured organic electrodes by field-induced charge-transfer

Abstract

Organic electrodes are promising candidates for the next-generation energy storage system of rechargeable lithium-ion batteries (LIBs) due to their natural abundance and lightweight. However, they have weaknesses: low electrochemical capacity, low capacity retention, and elution of active electrode materials. In this study, the field-induced charge-transfer route and nanostructuring are developed to resolve the poor electrochemical performance. When the 5,10-Dihydro-5,10-dimethylphenazine (DMPZ) with a nanoporous structure is homogeneously mixed with organic and metal nanoparticles (perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), perylenetetracarboxylic diimide (PTCDI), Flavanthrone, and Aluminum), the organic nanocomposite cathodes exhibit a remarkable enhancement in electrochemical performance: unprecedented cycling stability with capacity retention over 90% up to 600 redox cycles, a high specific capacity of 215 mA·h·g−1 at the current density of 150 mA·g−1, and an excellent rate-capability for the DMPZ and PTCDA nanocomposite cathode. The excellent specific capacity and retention of the redox reaction are due to the fast charge transport through the nanoporous network of the nanocomposites with a high specific surface area. The charge-transfer between the vicinal organic materials with different ionization energies is induced by the charging potential of the redox reaction, which suppresses the elution during the oxidation process and leads to the remarkable cyclability. The all-organic pouch-type full-cell, composed of a PTCDI anode and the nanocomposite cathode, is realized with excellent cyclability of 76% capacity retention at the 200th cycle. This work provides a promising way of developing stable organic electrodes for electrocatalytic applications as well as LIBs.