Aqueous aluminum batteries are promising post-lithium battery technologies for large-scale energy storage applications because of the raw materials abundance, low costs, safety and high theoretical capacity. However, their development is hindered by the unsatisfactory electrochemical behaviour of the Al metal electrode due to the presence of an oxide layer and hydrogen side reaction. To circumvent these issues, we report aluminum-copper alloy lamellar heterostructures as anode active materials. These alloys improve the Al-ion electrochemical reversibility (e.g., achieving dendrite-free Al deposition during stripping/plating cycles) by using periodic galvanic couplings of alternating anodic α-aluminum and cathodic intermetallic Al2Cu nanometric lamellas. In symmetric cell configuration with a low oxygen concentration (i.e., 0.13 mg L−1) aqueous electrolyte solution, the lamella-nanostructured eutectic Al82Cu18 alloy electrode allows Al stripping/plating for 2000 h with an overpotential lower than ±53 mV. When the Al82Cu18 anode is tested in combination with an AlxMnO2 cathode material, the aqueous full cell delivers specific energy of ~670 Wh kg−1 at 100 mA g−1 and an initial discharge capacity of ~400 mAh g−1 at 500 mA g−1 with a capacity retention of 83% after 400 cycles.

Metallic zinc (Zn) is one of the most attractive multivalent-metal anode materials in post-lithium batteries because of its high abundance, low cost and high theoretical capacity. However, it usually suffers from large voltage polarization, low Coulombic efficiency and high propensity for dendritic failure during Zn stripping/plating, hindering the practical application in aqueous rechargeable zinc-metal batteries (AR-ZMBs). Here we demonstrate that anionic surfactant-assisted in situ surface alloying of Cu and Zn remarkably improves Zn reversibility of 3D nanoporous Zn electrodes for potential use as high-performance AR-ZMB anode materials. As a result of the zincophilic ZnxCuy alloy shell guiding uniform Zn deposition with a zero nucleation overpotential and facilitating Zn stripping via the ZnxCuy/Zn galvanic couples, the self-supported nanoporous ZnxCuy/Zn electrodes exhibit superior dendrite-free Zn stripping/plating behaviors in ambient aqueous electrolyte, with ultralow polarizations under current densities up to 50 mA cm‒2, exceptional stability for 1900 h and high Zn utilization. This enables AR-ZMB full cells constructed with nanoporous ZnxCuy/Zn anode and KzMnO2 cathode to achieve specific energy of as high as ~ 430 Wh kg‒1 with ~ 99.8% Coulombic efficiency, and retain ~ 86% after long-term cycles for > 700 h.

Aluminum is an attractive anode material in aqueous multivalent-metal batteries for large-scale energy storage because of its high Earth abundance, low cost, high theoretic capacity, and safety. However, state-of-the-art aqueous aluminum-ion batteries based on aluminum anode persistently suffer from poor rechargeability and low coulombic efficiency due to irreversibility of aluminum stripping/plating and dendrite growth. Here eutectic aluminumcerium alloys in situ grafted with uniform ultrathin MXene (MXene/E-Al 97 Ce 3 ) as flexible, reversible, and dendrite-free anode materials for rechargeable aqueous aluminum-ion batteries is reported. As a result of the MXene serving as stable solid electrolyte interphase to inhibit side reactions and the lamellananostructured E-Al 97 Ce 3 enabling directional Al stripping and deposition by making use of symbiotic α-Al metal and intermetallic Al 11 Ce 3 lamellas, the MXene/E-Al 97 Ce 3 hybrid electrodes exhibit reversible and dendrite-free Al stripping/plating with low voltage polarization of ± 54 mV for ≥1000 h in a low-oxygen-concentration aqueous aluminum trifluoromethanesulfonate (Al(OTF) 3 ) electrolyte. These superior electrochemical properties endow softpackage aluminum-ion batteries assembled with MXene/E-Al 97 Ce 3 anode and Al x MnO 2 cathode to have high initial discharge capacity of ≈360 mAh g −1 at 1 A g −1 , and retain ≈85% after 500 cycles, along with the coulombic efficiency of as high as 99.5%.

Developing robust nonprecious-metal electrocatalysts with high activity towards sluggish oxygen-evolution reaction is paramount for large-scale hydrogen production via electrochemical water splitting. Here we report that self-supported laminate composite electrodes composed of alternating nanoporous bimetallic iron-cobalt alloy/oxyhydroxide and cerium oxynitride (FeCo/CeO2−xNx) heterolamellas hold great promise as highly efficient electrocatalysts for alkaline oxygen-evolution reaction. By virtue of three-dimensional nanoporous architecture to offer abundant and accessible electroactive CoFeOOH/CeO2−xNx heterostructure interfaces through facilitating electron transfer and mass transport, nanoporous FeCo/CeO2−xNx composite electrodes exhibit superior oxygen-evolution electrocatalysis in 1 M KOH, with ultralow Tafel slope of ~33 mV dec−1. At overpotential of as low as 360 mV, they reach >3900 mA cm−2 and retain exceptional stability at ~1900 mA cm−2 for >1000 h, outperforming commercial RuO2 and some representative oxygen-evolution-reaction catalysts recently reported. These electrochemical properties make them attractive candidates as oxygen-evolution-reaction electrocatalysts in electrolysis of water for large-scale hydrogen generation.

Designing highly selective and cost‐effective electrocatalysts toward electrochemical carbon dioxide (CO2) reduction is crucial for desirable transformation of greenhouse gas into fuels or high‐value chemical products. Here, the authors report intermetallic Cu3Sn that is in situ formed and seamlessly integrated on self‐supported bimodal nanoporous Cu skeleton (Cu3Sn/Cu) via a spontaneous alloying of Sn and Cu as robust electrocatalyst for selective electroreduction of CO2 to CO. By virtue of Sn atoms strengthening CO adsorption on Cu atoms, the intermetallic Cu3Sn has an intrinsic activity of ≈10.58 μA cm−2, more than 80‐fold higher than that of monometallic Cu. By virtue of hierarchical bicontinuous nanoporous Cu architecture facilitating electron transfer and CO2 and proton mass transport and offering high specific surface areas for full use of electroactive Cu3Sn sites, the nanoporous Cu3Sn/Cu hybrid electrodes produce CO at a low overpotential of 0.09 V, and exhibit high partial current density of ≈15 mA cm−2geo at overpotential of 0.59 V, along with excellent stability and selectivity of 91.5% Faradaic efficiency. The outstanding electrochemical performance make them attractive alternatives to precious Au‐ and Ag‐based electrocatalysts for building low‐cost CO2 electrolyzers to selectively produce CO.