Rechargeable batteries using aqueous electrolyte have intrinsically low flammability and are promising alternatives to lithium ion batteries for mid-and large-scale energy storages. Among aqueous battery anode materials, zinc metal stands out because of the highest energies (5846 Ah/L volumetric capacity, 3 times the amount of a lithium metal anode) and an operating potential near the lower limit of water stability window. However, the rechargeability of Zn anodes is hindered by passivation and dissolution problems associated with the solid-solute-solid transformation during cycling. Here we solve both problems simultaneously by designing a distinctive nanostructured zinc anode in which 100 nm ZnO nanoparticles are wrapped and segmented by graphene oxide (GO) sheets. The small size of primary ZnO nanoparticles prevents passivation, while the GO wrap and segmentation confine soluble Zn(OH) 4 2− intermediates from escaping. This lasagna-like nanostructured Zn anode measured a high volumetric capacity of 2308 Ah/L and achieved a remarkable capacity retention of 86% after 150 cycles. In contrast, the open-structured ZnO nanoparticle anode, without the protection of GO, completely died after 90 cycles.

Solid polymer electrolytes (SPEs) have the potential to enhance the safety and energy density of lithium batteries. However, poor interfacial contact between the lithium metal anode and SPE leads to high interfacial resistance and low specific capacity of the battery. In this work, we present a novel strategy to improve this solid–solid interface problem and maintain good interfacial contact during battery cycling by introducing an adaptive buffer layer (ABL) between the Li metal anode and SPE. The ABL consists of low molecular-weight polypropylene carbonate , poly­(ethylene oxide) (PEO), and lithium salt. Rheological experiments indicate that ABL is viscoelastic and that it flows with a higher viscosity compared to PEO-only SPE. ABL also has higher ionic conductivity than PEO-only SPE. In the presence of ABL, the interface resistance of the Li/ABL/SPE/LiFePO4 battery only increased 20% after 150 cycles, whereas that of the battery without ABL increased by 117%. In addition, because ABL makes a good solid–solid interface contact between the Li metal anode and SPE, the battery with ABL delivered an initial discharge specific capacity of >110 mA·h/g, which is nearly twice that of the battery without ABL, which is 60 mA·h/g. Moreover, ABL is able to maintain electrode–electrolyte interfacial contact during battery cycling, which stabilizes the battery Coulombic efficiency.

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Electrochemically responsive materials (ERMs) that respond to external electrical stimuli offer advanced control over physio-chemical processes with a high degree of tunability and flexibility. Recently, the use of ERMs in environmental remediation processes has increased to address the grand sustainability challenges associated with water scarcity and climate change. Here, we provide a timely review on the applications of ERMs to electrochemically mediated water treatment (EMWT) and electrochemically mediated carbon capture (EMCC). We first examine the working principles of ERMs-based systems for water treatment and carbon capture, followed by a detailed summary of key figures of merit that quantify the overall performance. Second, we present an in-depth discussion of the multiscale design principles of EMWT and EMCC systems, ranging from materials-level engineering to electrode-level considerations to device configuration optimization. Next, we discuss the development and application of in situ and operando characterization methods, with a particular emphasis on imaging tools, which uncover ubiquitous static and dynamic heterogeneities in ERMs and critically inform rational materials design. Finally, we point out future opportunities and challenges in the emerging field of electrochemically mediated environmental remediation, including developing new tools to monitor complex multiphase transport and reactions, repurposing existing energy nanomaterials for environmental technologies, and scaling and combining EMWT and EMCC systems.