In situ crosslinkable small molecule organic cathode with self-nanostructuring property for stable and fast-rechargeable batteries

Redox-active organic materials (ROMs) for energy storage devices are emerging as sustainable alternatives to inorganic cathode materials. However, the development of high-performance organic cathodes has been challenged by the incompatibility between the insolubilization of ROMs for high stability and the fabrication of electrodes with high surface area for high-rate capability. Herein, we present a small-molecule organic cathode material, 1,3,5-tris(3-vinyl-10H-phenoxazin-10-yl)benzene (V3PXZ), that overcomes this limitation by in situ electrochemical crosslinking in the cell after electrode fabrication using soluble small-molecule. V3PXZ is designed to form a non-conjugated polymer without byproducts through in situ electrochemical crosslinking to ensure the coupling reaction does not degrade cell performance. This method not only yields an insoluble network of V3PXZ, but also forms nanostructures with high surface area in the electrode. Utilizing self-nanostructuring, we demonstrate an aqueous-processed V3PXZ cathode operating at a voltage of 3.87 V vs. Li/Li+, comparable to inorganic cathodes. Notably, V3PXZ simultaneously achieves the highest cycling stability (capacity retention of 99.995% per cycle over 10,000 cycles) and rate capability (charging 56% of total capacity in 36 seconds) with the highest active content (70 wt%) among the small molecule organic p-type cathodes reported to date.