Highly Thermally/Electrochemically Stable I⁻/I₃⁻Bonded Organic Salts with High I Content for Long‐Life Li–I₂Batteries

Abstract

chemistry to achieve high energy and power densities, in which their novel chemical processes have attracted considerable attention. [1][2][3][4][5][6][7][8] So far, diversified metal-halogen batteries such as zinc-iodine, [9][10][11][12] zinc-bromine, [13,14,15] lithium-iodine, [16][17][18] lithium-bromine/ chlorine, [2,19,20] sodium-iodine, [21,22] magnesium-iodine [23,24] and other metal-halogen batteries [25][26][27][28][29] have been developed owing to the high compatibility of halogen cathodes with metal anodes. Among the emerging energy storage systems, rechargeable non-aqueous lithium iodine (Li-I 2 ) batteries are promising next-generation technologies featuring desired energy density, sustainability and affordability due to the earth-abundant (50-60 µg iodine L −1 in the ocean), highly reversible iodine cathode, as well as high-capacity and low-electrode-potential (−3.04 V versus standard hydrogen electrode) of Li metal anode. [32] Better operability and stability of solid iodine compared to liquid bromine and gaseous chlorine make it stand out among the halogen electrode materials. Nevertheless, the poor thermodynamic stability and shuttle effect of polyiodide ions are still long-standing challenges to the practical implementation of rechargeable iodine batteries. [21,[33][34][35] Exhaustive efforts have been devoted to stabilizing the iodine cathode and boosting the redox kinetics. Introducing conductive hosts, such as nanoporous carbons [3,36,37] (such as reduced graphene oxide, activated carbon, hollow carbon sphere, activated carbon cloth) or interlayer storage of iodine in two-dimensional MXene, [6] and direct adoption of iodine-containing electrolytes are two typical representatives. [10,38,39] The conductive host tactics, generally show moderate enhancement due to the low sublimation temperature of iodine. The inevitable introduction of non-active components results in low iodine content and limited energy density. While electrolyte regulation is an expensive and uncontrollable method, which experimentally leads to the underutilization of active iodine.Towards the thermodynamic instability and shuttle effect issues of iodine electrodes, introducing robust chemical bonding should be one of the most effective ways. [3] Instead of Rechargeable lithium-iodine batteries are highly attractive energy storage systems featuring high energy density, superior power density, sustainability, and affordability owing to the promising redox chemistries of iodine. However, severe thermodynamic instability and shuttling issues of the cathode have plagued the active iodine loading, capacity retention and cyclability. Here the development of highly thermally and electrochemically stable I − /I 3 − -bonded organic salts as cathode materials for Li-I 2 batteries is reported. The chemical bonding of iodine/polyiodide ions with organic groups allows up to 80 wt% iodine to be effectively stabilized without sacrificing fast and reversible redox reaction activity. Thus, the shuttle effect is significantly inhibited, whic...

Development of long lifespan high-energy aqueous organic||iodine rechargeable batteries

“…In recent years, rechargeable metal-halogen batteries, which rely on strict redox chemistry to achieve high energy and power density, have attracted considerable attention 1 – 6 . In particular, solid iodine (I 2 ) has shown better operability and (electro)chemical stability than its liquid bromine and gaseous chlorine analogs 7 – 10 .…”

Incorporating Conducting Polypyrrole into a Polyimide COF for Carbon‐Free Ultra‐High Energy Supercapacitor

“…) form, an energetically stabler species. [43][44][45] We confirmed the presence of I 3 − and its ionic type interaction with pyrrole nitrogen from X-ray photoelectron spectroscopy (XPS) analysis. All the iodide (I 3d) XPS spectra display the peaks with binding energy corresponding to the II bond of I 3 − species (618.6 eV).…”

“…The small amounts of iodine added during the polypyrrole synthesis in the presence of COF are expected to form I − or I 3 − species, which will counter-balance the cationic oxidized sites in the Ppy chains. [43,44] The energy dispersive X-ray analysis (EDX) and the elemental mapping of the Ppy@COF reveals uniformly dispersed iodine species (Figure S16, Supporting Information). This iodide can also be present in polyiodide (I 3…”

Eliminating Lightning‐Rod Effect of Lithium Anodes via Sine‐Wave Analogous MXene Layers

“…Owing to the high theoretical specific capacity (3680 mAh g −1 ) and low electrochemical redox potential (−3.04 V vs the standard hydrogen electrode), metallic lithium (Li) anode has been regarded as the most promising candidate for lithium-based batteries. [1][2][3][4] Unfortunately, during repeated charge-discharge processes, drastic metallic Li dendrites are easy to be generated at the surface of Li anodes. [5][6][7][8] Moreover, the uncontrollable Li dendrites cause a series of issues such as severe volume changes, low Coulombic efficiency (CE) as well as poor cycle life, which impede the commercial application of Li anodes.…”