A Donor-Acceptor-Donor-type Organic Molecule as an Effective Electrode to Form Rapid Diffusion Pathway for...

Carbonyl-containing organic electrodes have been widely considered as ideal substitutes for traditional inorganic compounds in sodium-ion batteries (SIBs) due to their excellent redox reversibility and structural tunability. However, constructing effective Na⁺ diffusion channels in these materials is very challenging. To address this issue, we design a new organic molecule, N,N'-bis(3,4,5-trimethoxyphenyl)-1,4,5,8-naphthalenediimide (NDI-DTMA), containing a donor-acceptor-donor (D-A-D) structure. The D-A-D architecture significantly enhances π-conjugation extent of single organic material while narrowing its bandgap, facilitating electron transportation along the NDI-DTMA skeletons. Moreover, 3,4,5-trimethoxyphenyl groups not only suppress dissolution issue but also enlarge the intermolecular planar spacing for Na⁺ mobility through constructing efficient transport channels. As an electrode material for SIBs, NDI-DTMA achieves a reversible capacity of 200 mAh g^-1 after 2000 cycles at 1 A g^-1 owing to its fast Na⁺ kinetics. Through systematic investigation on the anomalous capacity increase and the dynamic evolution of solid electrolyte interphase (SEI), we have elucidated the fundamental mechanisms that the distinctive NDI-DTMA architecture enables exceptional energy storage performance. This work pioneers a design paradigm of organic small molecules that simultaneously address low solubility, high conductivity, and rapid ion transport, thereby providing a transformative strategy for SIBs.