The propensity of metals to form irregular and nonplanar electrodeposits at liquid-solid interfaces has emerged as a fundamental barrier to high-energy, rechargeable batteries that use metal anodes. We report an epitaxial mechanism to regulate nucleation, growth, and reversibility of metal anodes. The crystallographic, surface texturing, and electrochemical criteria for reversible epitaxial electrodeposition of metals are defined and their effectiveness demonstrated by using zinc (Zn), a safe, low-cost, and energy-dense battery anode material. Graphene, with a low lattice mismatch for Zn, is shown to be effective in driving deposition of Zn with a locked crystallographic orientation relation. The resultant epitaxial Zn anodes achieve exceptional reversibility over thousands of cycles at moderate and high rates. Reversible electrochemical epitaxy of metals provides a general pathway toward energy-dense batteries with high reversibility.

The propensity of metal anodes of contemporary interest (e.g., Li, Al, Na, and Zn) to form non-planar, dendritic morphologies during battery charging is a fundamental barrier to achievement of full reversibility. We experimentally investigate the origins of dendritic electrodeposition of Zn, Cu, and Li in a three-electrode electrochemical cell bounded at one end by a rotating disc electrode. We find that the classical picture of ion depletion–induced growth of dendrites is valid in dilute electrolytes but is essentially irrelevant in the concentrated (≥1 M) electrolytes typically used in rechargeable batteries. Using Zn as an example, we find that ion depletion at the mass transport limit may be overcome by spontaneous reorientation of Zn crystallites from orientations parallel to the electrode surface to dominantly homeotropic orientations, which appear to facilitate contact with cations outside the depletion layer. This chemotaxis-like process causes obvious texturing and increases the porosity of metal electrodeposits.

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Understanding cation (H+, Li+, Na+, Al3+, etc.) intercalation/de‐intercalation chemistry in transition metal compounds is crucial for the design of cathode materials in aqueous electrochemical cells. Here we report that orthorhombic vanadium oxides (V2O5) supports highly reversible proton intercalation/de‐intercalation reactions in aqueous media, enabling aluminum electrochemical cells with extended cycle life. Empirical analyses using vibrational and x‐ray spectroscopy are complemented with theoretical analysis of the electrostatic potential to establish how and why protons intercalate in V2O5 in aqueous media. We show further that cathode coatings composed of cation selective membranes provide a straightforward method for enhancing cathode reversibility by preventing anion cross‐over in aqueous electrolytes. Our work sheds light on the design of cation transport requirements for high‐energy reversible cathodes in aqueous electrochemical cells.

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Composite Bi@Bi 2 O 3 microspheres have been synthesized via a microwave-assisted solvothermal route. The Bi@Bi 2 O 3 microspheres had a narrow size distribution in the range 1.2-2.8 mm. Glucose was selected as the reductant, BiCl 3 as the bismuth source, and ethylene glycol (EG) as the solvent in the synthesis system. The as-synthesized sample was characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle diameter distribution, energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence (PL) spectroscopy. The photocatalytic activities of the Bi@Bi 2 O 3 microspheres were evaluated by the photodegradation of rhodamine B (RhB) and methyl orange (MO) dyes under UV light irradiation. The degradation reached ~96.6% for RhB and 100% for MO after 4 h reaction in the presence of the as-synthesized Bi@Bi 2 O 3 microspheres.

Incorporation of reduced graphene oxide into β-Ni(OH)(2) presents high performances with specific discharge capacity of 283 mA hg(-1) after 50 cycles in Ni-MH batteries, and 507 mA hg(-1) after 30 cycles in Li ion batteries.

Control of crystallography of metal electrodeposit films has recently emerged as a key to achieving long operating lifetimes in next‐generation batteries. It is reported that the large crystallographic heterogeneity, e.g., broad orientational distribution, that appears characteristic of commercial metal foils, results in rough morphology upon plating/stripping. On this basis, an accumulative roll bonding (ARB) methodology—a severe plastic deformation process—is developed. Zn metal is used as a first example to interrogate the concept. It is demonstrated that the ARB process is highly effective in achieving uniform crystallographic control on macroscopic materials. After the ARB process, the Zn grains exhibit a strong (002) texture (i.e., [002]Zn//ND). The texture transitions from a classical bipolar pattern to a nonclassical unipolar pattern under large nominal strain eliminate the orientational heterogeneity of the foil. The strongly (002)‐textured Zn remarkably improves the plating/stripping performance by nearly two orders of magnitude under practical conditions. The performance improvements are readily scaled to achieve pouch‐type full batteries that deliver exceptional reversibility. The ARB process can, in principle, be applied to any metal chemistry to achieve similar crystallographic uniformity, provided the appropriate temperature and accumulated strains are employed. This concept is evaluated using commercial Li and Na foils, which, unlike Zn (HCP), are BCC crystals. The simple process for creating strong textures in both hexagonal and cubic metals and illustrating the critical role such built‐in crystallography plays underscores opportunities for developing highly reversible thin metal anodes (e.g., hexagonal Zn, Mg, and cubic Li, Na, Ca, Al).