A representative large π-conjugated molecule, bilirubin, is grafted onto multi-faceted Zn substrates to induce interfacial charge redistribution, elevate the Zn d-band center, and enhance H+ fixation at the Zn/electrolyte interface. This strategy effectively suppresses Zn dendrite growth and hydrogen evolution reaction, resulting in stable Zn-ion batteries with long-term cycling performance.
Abstract
Undesirable dendrite growth and side reactions at the electrical double layer (EDL) of Zn/electrolyte interface are critical challenges limiting the performance of aqueous zinc ion batteries. Through density functional theory calculations, we demonstrate that grafting large π-conjugated molecules (e.g. bilirubin, biliverdin, lumirubin, and hemoglobin) onto Zn surface induces preferential adsorption on non-(002) facets, leading to interfacial charge redistribution, upshifted Zn d-band center, and enhanced H+ fixation capability. Among these, bilirubin (BR) is identified as the most effective, preferentially adsorbing onto non-Zn(002) facets to inhibit hydrogen evolution reaction and promote Zn(002) planar growth during plating. This approach results in average Coulombic efficiency of 99.86 % over 4000 cycles in Zn||BR-1@Cu cells and prolonged lifespan exceeding 1600 h in BR-1@Zn||BR-1@Zn cells at 10 mA cm−2 and 1 mAh cm−2. Even under harsh conditions of 25 mA cm−2 and 10 mAh cm−2, BR-1@Zn||BR-1@Zn cell maintains a lifespan of over 400 h. Furthermore, BR-1@Zn||MnO2 and BR-1@Zn||NVO full cells achieve 76.4 % and 86.1 % capacity retention after 800 and 1400 cycles at 1.0 A g−1, respectively. This study underscores the importance of grafting large π-conjugated molecules to allow selective Zn(002) exposure, Zn d-band center upshift, and EDL structure regulation, paving the way towards durable Zn anodes.
