energy-storage systems with high specific energy, long lifespan, and excellent safety. [5][6][7] Among them, the rechargeable secondary batteries have been demonstrated as the most promising candidate for electricity storage and utilization. [8][9][10][11] As one of the most popular batteries, lithium-ion batteries (LIBs) have found immense success in consumer electronics and electric vehicles, and are under the consideration for energy-storage power stations. [12][13][14] However, the commercial LIBs based on transition metal-based inorganic compounds have encountered a bottleneck. [15][16][17] The charge storage of inorganic electrode materials is governed by the oxidation-state variation of transition metal centers and achieved a charge balance with the insertion of counterions. [18] Restricted by crystal lattice and structure stability, the size and valence of counterions are required to match the crystal structures, which severely limit further improvement of energy density. [19][20][21] Clearly, these factors intrinsically weaken the versatility of inorganic materials. For instance, the similar electrode materials, which are successful in LIBs, are not suitable for other alkali ions batteries. [22][23][24] Additionally, from the viewpoint of economical and renewable factors of mineral resources, the existing LIBs based on transition metals (e.g., cobalt, nickel, and manganese) are difficult to meet the requirement of large-scale energy storage. [25] Nowadays, various demands have been raised up for the state-ofthe-art batteries, not only in the enhancement of cycle life, fast charging, and safety, but also in the focus of cost, lightweight, pollution-free, and environmental benign. [26,27] Under this background, researchers gradually shift their studies on novel batteries system and electrode materials. [28][29][30][31] Among them, explorations on the possibility of using organic compounds as potential alternatives of current inorganic electrode materials have never been stopped. [32,33,66] Organics have been demonstrated as promising electrode candidates due to their variety, sustainability, relatively low cost, and environmental friendliness. [34][35][36] The structural diversity implies that the richness of organic materials will provide abundant options and room in this field. The molecule engineering means that the electrochemical properties of organic electrodes can be rationally tuned with different functional groups, which exhibits a good designability of organic materials. These important features allow various designable synthetic routes and convenient functionalization. Although organic electrode materials are endowed with many advantages, their development and Covalent-organic frameworks (COFs), featuring structural diversity, framework tunability and functional versatility, have emerged as promising organic electrode materials for rechargeable batteries and garnered tremendous attention in recent years. The adjustable pore configuration, coupled with the functionalization of frameworks through ...

Conspectus Lithium-ion batteries have received significant attention over the last decades due to the wide application of portable electronics and increasing deployment of electric vehicles. In order to further increase the energy density of batteries and overcome the capacity limitations (<250 mAh g–1) of inorganic cathode materials, it is imperative to explore new cathode materials for rechargeable lithium batteries. Organic compounds including organic carbonyl, radicals, and organosulfides are promising as they have advantages of high capacities, abundant resources, and tunable structures. In the 1980s, a few organosulfides, in particular organodisulfides, as cathode materials were studied to a certain extent in rechargeable lithium batteries. However, they showed low capacities and poor cycling performance, which made them unappealing then in comparison to transition metal oxide cathode materials. As a result, organosulfides have not been extensively studied like other cathode materials including organic carbonyls and radicals. In recent years, organosulfides with long sulfur chains (e.g., trisulfide, tetrasulfide, pentasulfide, etc.) in the structures have been receiving more attention in conjunction with the development of lithium–sulfur batteries. As a major class of sulfur derivatives, they have versatile structures and unique properties in comparison with elemental sulfur. In this Account, we first generalize the working principles of organosulfides in lithium batteries. We then discuss organosulfide molecules, which have precise lithiation sites and tunable capacities. The organic functional groups can provide additional benefits, such as discharge voltage and energy efficiency enhancement by phenyl groups and cycling stability improvement by N-heterocycles. Furthermore, replacing sulfur by selenium in these compounds can improve their electrochemical properties due to the high electronic conductivity and low bond energy associated with selenium. We list organosulfide polymers consisting of phenyl rings, N-heterocycles, or aliphatic segments. Organosulfides as electrolyte additives or components for forming a solid–electrolyte interphase layer on lithium metal anode are also presented. Carbon materials such as carbon nanotubes and reduced graphene oxide can enhance the battery performance of organosulfide cathodes. We discuss the synthesis methods for polysulfide molecules and polymers. Finally, we show the advantages of organosulfides over sulfur as cathode materials in lithium batteries. This Account provides a summary of recent development, in-depth analysis of structure–performance relationship, and guidance for future development of organosulfides as promising cathode materials for next generation rechargeable lithium batteries.

Conventional lithium‐ion batteries have approached their capacity and energy density limits. Use of lithium metal anode can enable high‐energy batteries. However, the safety hazards and lithium dendrite formation associated with lithium metal require safe electrolytes to replace flammable liquid ones. In recent years, solid‐state electrolytes have attracted tremendous attention. Among them, composite polymer electrolytes (CPEs) with different constitutions have the unique advantages of low interfacial resistance, high ionic conductivity, and flexible characteristics. Here, the basic properties and analysis methods related to CPEs are discussed. Following that, the components added into the polymer matrix, such as organic solvents, nanostructured ceramics, and fast‐ion‐conductive inorganics are classified. CPEs used in low‐cost Na and K batteries are briefly discussed. It is hoped that the review can supply both advances and fundamentals to the researchers in this field and provide guidance for the development of CPEs for lithium battery systems, and beyond.

Searching new organic cathode materials to address the issues of poor cycle stability and low capacity in lithium ion batteries (LIBs) is very important and highly desirable. In this research, a 2D boroxine‐linked chemically‐active pyrene‐4,5,9,10‐tetraone (PTO) covalent organic framework (2D PPTODB COFs) was synthesized as an organic cathode material with remarkable electrochemical properties, including high electrochemical activity (four redox electrons), safe oxidation potential window (between 2.3 and 3.08 V vs. Li/Li+), superb structural/chemical stability, and strong adhesiveness. A binder‐free cathode was obtained by mixing 70 wt % PPTODB and 30 wt % carbon nanotubes (CNTs) as a conductive additive. Promoted by the fast kinetics of electrons/ions, high electrochemical activity, and effective π–π interaction between PPTODB and CNTs, LIBs with the as‐prepared cathode exhibited excellent electrochemical performance: a high specific capacity of 198 mAh g−1, a superb rate ability (the capacity at 1000 mA g−1 can reach 76 % of the corresponding value at 100 mA g−1), and a stable coulombic efficiency (≈99.6 % at the 150th cycle). This work suggests that the concept of binder‐free 2D electroactive materials could be a promising strategy to approach energy storage with high energy density.

The interfacial instability of the lithium-metal anode and shuttling of lithium polysulfides in lithium-sulfur (Li-S) batteries hinder the commercial application. Herein, we report a bifunctional electrolyte additive, i.e., 1,3,5-benzenetrithiol (BTT), which is used to construct solid-electrolyte interfaces (SEIs) on both electrodes from in situ organothiol transformation. BTT reacts with lithium metal to form lithium 1,3,5-benzenetrithiolate depositing on the anode surface, enabling reversible lithium deposition/stripping. BTT also reacts with sulfur to form an oligomer/polymer SEI covering the cathode surface, reducing the dissolution and shuttling of lithium polysulfides. The Li–S cell with BTT delivers a specific discharge capacity of 1,239 mAh g−1 (based on sulfur), and high cycling stability of over 300 cycles at 1C rate. A Li–S pouch cell with BTT is also evaluated to prove the concept. This study constructs an ingenious interface reaction based on bond chemistry, aiming to solve the inherent problems of Li–S batteries.

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Accompanied by the enhancement of ability to fabricate materials for human, alloy-based materials have advanced from binary alloy systems to complicated compositions with opening up new applications, which accelerate the...

Cross-shaped and octahedral nanoparticles (hexapods) of MnO in size, and fragments thereof, are created in an amine/carboxylic acid mixture from manganese formate at elevated temperatures in the presence of water. The nanocrosses have dimensions on the order of 100 nm, but with exposure to trace amounts of water during the synthesis process they can be prepared up to about 300 nm in size. Electron microscopy and X-ray diffraction results show that these complex shaped nanoparticles are single crystal face-centered cubic MnO. In the absence of water, the ratio of amine to carboxylic acid determines the nanocrystal size and morphology. Conventionally shaped rhomboehdral/square nanocrystals or hexagonal particles can be prepared by simply varying the ratio of tri-n-octylamine/oleic acid with sizes on the order of 35-40 nm in the absence of added water. If the metal salt is rigorously dried before the synthesis, then "flower-shaped" morphologies on the order of 50-60 nm across are observed. Conventional squareshaped nanocrystals with clearly discernible thickness fringes that also arise under conditions producing the nanocrosses mimic the morphology of the cross-shaped and octahedral nanocrystals and provide clues to the crystal growth mechanism(s), which agree with predictions of crystal growth theory from rough, negatively curved surfaces. The synthetic methodology appears to be general and promises to provide an entryway into other nanoparticle compositions.