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Deeply understanding the chemical heterogeneity of graphite anode is important because it can provide insights into the underlying mechanisms of electrode degradation and failure in battery systems. Herein, the chemical heterogeneity of graphite anode is imaged by X-ray fluorescence mode scanning transmission X-ray microscope (XRF-STXM) to space-resolve the chemical distribution and structure at C, O, F and Na sites. The synchrotron radiation X-ray photoelectron spectroscopy analysis suggests that the solid-electrolyte-interphase (SEI) layer on graphite anodes contains a complex mixture of both organic (-COOR, -C-OR, etc.) and inorganic species (CO 3 2−, LiF, Li x PO y F z , etc.), which can vary with depth. Furthermore, XRF-STXM imaging combined with X-ray absorption spectra is used to map out the heterogeneity in the chemical spatial distribution of SEI composition and its location dependence, as well as its strong correlation with the distribution of conductive additives/binders and binders decomposition. The distribution of SEI exhibits a distinctive feature, with the CO 3 2− and LiF species being significantly thicker at edge plane than at basal plane and the distribution being highly non-uniform. The insights gained from the visualization of the spatial chemical distribution will deepen our understanding of SEI, which is crucial for delineating effective strategies for the development of Li-ion batteries. • Used SR-XPS, XRF-STXM, XAS to visualize chemical heterogeneity distribution of SEI. • SEI layer contains a depth-dependent mixture of organic and inorganic species. • Spatially mapped out SEI chemical distribution and correlation with additives/binders. • Non-uniform SEI distribution: thicker CO 3 2− and LiF at edge compared to basal plane. • Highlight XRF-STXM's potential for high-resolution chemical imaging of electrode. [ABSTRACT FROM AUTHOR]

Schematic diagram of the X-Treated Zn alloy electrode preparation process. [Display omitted] • Stronger (0 0 2) crystal plane inhibited side reaction with high adsorption energy to Zn2+ but low adsorption energy to water molecule, simultaneously changed Zn2+ deposition behavior. • Chloride and carbon compounds act as a functional protective layer. • The in-situ alloying phase induced dense deposition triggered by the modulation of the Zn2+ flux at the modified zinc surface. • With the integration of the composite layer, the symmetric cell with modified zinc electrode demonstrated lower polarization potential at 1.0 mA cm−2 and 2.0 mA cm−2. • The exceptionally stable cycling potential also testified the restraint of side reaction and dendrite growth for the modified zinc electrode. Rechargeable aqueous zinc-ion batteries are considered as the promising alternative for lithium-ion batteries due to their high safety, eco-friendly and low cost. However, problems, such as dendritic growth and corrosion reaction for zinc anode, hinder their further development. Here, combustion process is applied to modulate zinc electrode interface so as to solve above challenges, which disclose profound consequence for the zinc anode reversibility. Three functional layers can be constructed simultaneously:Induced stronger zinc (0 0 2) crystal plane resulting in corrosion resistance; In situ formed alloy phase also making modulation of ion flux with uniform and dense deposition; Adsorbed extra the chloride and carbon compounds acting solid electrolyte layer assessing in ion continuous transfer. As a result, Zn-X electrodes (ZXEs) exhibit lower polarization voltage and longer cycling life than pure Zn. In situ optical microscope monitors the ion nucleation behavior where no dendrites and side reactions for ZXEs can be found. Coupled with vanadium oxide cathode, the full cell exhibits better rate capability and 1000 cycles as well as good capacity retention. Consequently, this study provides a facile and unique strategy for advanced aqueous zinc batteries practical application with interfacial engineering. [ABSTRACT FROM AUTHOR]

• Zincophilic layer were constructed on Zn anode via simple soaking strategy. • The artificial layer can regulate Zn2+ flux as verified by COMSOL simulation. • The decorated Zn anode displays ultralong lifespan over 4800 h. • Dendrite-free Zn anode were achieved with high CPC of 6900 mAh cm−2. Aqueous zinc-ion batteries have been highly valued for their high safety and environmental friendliness. However, the notorious Zn dendrite growth derived from uneven distribution of electric fields and side reaction at the electrolyte–anode interface critically limited the lifespan of aqueous zinc-ion batteries. Herein, uniform zinc deposition were achieved by construction of interface film with prussian blue 3D open framework, which provide highly zincophilic channel with well-regulated Zn2+ flow tailored on Zn anode surface. The decorated Zn electrode displayed an ultralong plating/stripping cycling life over 4800 h with an ultralow voltage hysteresis (30 mV) at current density of 0.25 mA cm−2. Moreover, the modified Zn||Cu half cell delivers high average coulombic efficiency up to 99.2% for more than 1000 cycles at 0.5 mA cm−2. When coupled with MnO 2 cathode, the full cells demonstrated significantly improved cycling stability with capacity retention of 85.1% after 200 cycles. The facile construction strategy of interface layer with well-regulated Zn2+ flow developed in this work provided promising perspective for the design of long term aqueous Zn battery. [ABSTRACT FROM AUTHOR]