A facile finger-paint physical modification for bilateral electrode/electrolyte interface towards a stable aqueous Zn battery

Since the electrode/electrolyte interface (EEI) is the main redox center of electrochemical processes, proper manipulation of the EEI microenvironment is crucial to stabilize interfacial behaviors. Here, a finger–paint method is proposed to enable quick physical modification of glass–fiber separator without complicated chemical technology to modulate EEI of bilateral electrodes for aqueous zinc–ion batteries (ZIBs). An elaborate biochar derived from Aspergillus Niger is exploited as the modification agent of EEI, in which the multi–functional groups assist to accelerate Zn2+ desolvation and create a hydrophobic environment to homogenize the deposition behavior of Zn anode. Importantly, the finger–paint interface on separator can effectively protect cathodes from abnormal capacity fluctuation and/or rapid attenuation induced by H2O molecular on the interface, which is demonstrated in modified MnO2, V2O5, and KMnHCF–based cells. The as–proposed finger–paint method opens a new idea of bilateral interface engineering to facilitate the access to the practical application of the stable zinc electrochemistry.