Cyano-bridged coordination polymer gel as a precursor to a nanoporous In₂O₃–Co₃O₄ hybrid network for high-capacity and cycle-stable lithium storage

Abstract

A cyanogel-derived three-dimensional nanoporous In2O3–Co3O4 hybrid network as a high-capacity and long-life anode material for lithium-ion batteries.

Inorganic Cyanogels and Their Derivatives for Electrochemical Energy Storage and Conversion

“…Classic inorganic gels are obtained through the polymerization of oxo species, yielding typical oxide-based networks. Differentiated from the metal–oxo gels, cyanogels are cyano-bridged inorganic gels and are generally formed via ligand-substitution reactions between main-group or noble-metal chlorides/chlorometalates (M′ = Sn, − In, − Sb, Pd, − ,− Pt, ,,, Rh, , etc.) and transition-metal cyanometalates (M′′ = Fe, Co, Ni, etc.)…”

“…Nanostructured gels possess a tunable structure and composition, a highly porous structure, an effective pathway for charge/mass transport, and ease of synthesis and functionalization and thus have emerged as ideal material platforms for electrochemical energy storage and conversion. − Recently, various gels and their derivatives, including graphene gels, conductive polymer gels, − ionically conductive gels, , and so on, have been extensively developed and utilized as advanced electrodes, binders, electrolytes, and electrocatalytic materials for energy-related applications. As a special class of inorganic gels, cyanogels refer to cyano-bridged coordination polymer gels, which were pioneered by Bocarsly et al in 1993. − Cyanogels are generally formed through ligand-substitution reactions between main-group or noble-metal chloride/chlorometalate (M′ = Sn, In, Sb, Pd, Pt, Rh, etc.) and transition-metal cyanometalate (M′′ = Fe, Co, Ni, etc.)…”

“…and transition-metal cyanometalate (M′′ = Fe, Co, Ni, etc.) solutions. − Early research regarding cyanogels primarily focused on their synthesis and physicochemical properties. − …”

“… With the development of nano and energy technologies, the heterometallic nature, as well as the interconnected framework structure of cyanogels, makes them become useful material platforms for advanced energy technologies. − The unique structural and compositional features of cyanogels and their derivatives toward electrochemical energy storage and conversion can be specified as follows: − (1) The gel framework possesses high structural integrity while providing charge/mass-transfer channels, ensuring long-term cycling life and fast reaction kinetics. (2) Different from metal-free and monometallic gels, cyanogels are heterometallic gels, incorporate both M′ and M′′ bridged by cyano group (M′–NC–M′′) on their scaffolds, and can further convert into homogeneous alloy, alloy@carbon, and hybrid oxide frameworks.…”

“…(3) Cyanogels possess a flexible framework structure and a tunable composition and can serve as ideal matrices to introduce functional species to build hybrid gels with new physicochemical properties or markedly improved electrochemical performances. With the above-mentioned features, cyanogels and their derivatives show great potential and have been demonstrated to be promising energy materials for rechargeable metal-ion batteries, metal-air batteries, and fuel cells. − …”