Fabrication of porous electrodes by fusion of silver particles

Description (excerpt)

REFERENCE TO RELATED APPLICATIONS This application is a continuation application of U.S. application Ser. No. 18/328,020, filed on Jun. 2, 2023, which is a continuation-in-part application of U.S. Pat. No. 11,710,818, issued on Jul. 25, 2023, which claims the benefit of U.S. Provisional Application No. 63/299,071, filed on Jan. 13, 2022. The provisional application and all other publications and patent documents referred to throughout this nonprovisional application are incorporated herein by reference. TECHNICAL FIELD The present disclosure is generally related to silver electrodes for electrochemical devices. DESCRIPTION OF THE RELATED ART Zinc electrodes historically have had limited cycle life due to operando formation of dendrites that short-circuit the battery when they grow long enough to pierce the cell's separator and make electrical contact with the opposing electrode. Related problems of electrode degradation also plague the silver/silver oxide cathodes that are used in alkaline Ag-Zn batteries. A solution to this dendrite-forming problem is to fabricate the Zn anode as an aperiodic pore-solid architecture in which the 3D-interconnected void volume is co-continuous with the 3D-interconnected solid zinc network, i.e., a “sponge” form factor (Hopkins et al. (2020) Sustain. Energy and Fuels 4, 3363-3369; Hopkins et al. (2020) Energy Storage Mater. 27, 370-376; Hopkins et al. (2020) J. Vis. Exp . (163); Ko et al. (2018) ACS Appl. Energy Mater. 2, 212-216; Parker et al. (2017) Science 356, 415-418; Parker et al. (2016) J. Electrochem. Soc. 163, A351-A355; Parker et al. (2014) Energy Environ. Sci. 7, 1117-1124). The metallic, conductive, three-dimensional pathways improve current distribution throughout the electrode structure and avoid uneven reaction loci where formation of dendrites is likely to occur during charge-discharge cycles. In addition, the void network intertwined around the 3D zinc scaffold allows for confined volume elements with high ratios of surface (zinc) to volume (electrolyte); confinement induces saturation of zincate at lower concentrations than occurs in open solution; thus dehydration to zinc oxide (ZnO) occurs earlier in the discharge process, thereby further minimizing shape change. These previous Zn-sponge fabrication protocols used emulsion-based compositions that required organic pore-forming agents (carboxymethyl cellulose (CMC) or cornstarch). After drying and consolidation of the zinc-porogen object and subsequent thermal processing under inert gas flow (nitrogen or argon), the organic porogen must then be removed by heating in an oxygen-containing environment, typically air, causing excess oxidation of zinc to zinc oxide. The entire process is conducted in a furnace and takes ˜10 hours for tube purging, thermal ramping, and cooling. SUMMARY OF THE INVENTION Disclosed herein is a method comprising: providing a mixture comprising first particles comprising silver or silver oxide and second particles comprising an inorganic porogen, molding the mixture, cohering the mixture to form a green body, heating the green body to form a monolith, to convert any silver oxide to silver, and to fuse the first particles together, and submerging the monolith in a liquid that removes the second particles. Also disclosed herein is an electrode made by a method comprising: providing a mixture comprising first particles comprising silver or silver oxide and second particles comprising an inorganic porogen, molding the mixture, cohering the mixture to form a green body, heating the green body to form a monolith, to convert any silver oxide to silver, and to fuse the first particles together, and submerging the monolith in a liquid that removes the second particles. BRIEF DESCRIPTION OF DRAWINGS A more complete appreciation will be readily obtained by reference to the following Description of the Example Embodiments and the accompanying drawings. FIG. 1 shows X-ray diffraction (XRD) pattern of zinc monolith (Method 1) after thermal treatment (580° C., 1 h) and 10 min washing in 1M HCl. FIG. 2 shows a photograph of Zn sponge monoliths fabricated using an inorganic porogen (Method 1) as molded into different form factors. FIG. 3 shows scanning electron micrographs of zinc monoliths synthesized by Method 1. The micrographs show internal