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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 ...

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Nanostructured conjugated polymers are a type of electrochemically active organic material with a high electronic conductivity, good electrochemical stability, and superior flexibility. Owing to these advantages, increasing research interest has been recently focused on the utilization of nanostructured conjugated polymers as green and renewable resources for potential high-performance energy storage and conversion devices. This Review discusses the current situation and the state-of-the-art developments on nanostructured conjugated polymers including their one- and two-dimensional (1D and 2D) structures as well as their three-dimensional (3D) composite forms as electrode materials for rechargeable batteries. In particular, the fundamentals, challenges, and possible directions to improve the performance of the current systems are included in this Review. With sufficient depth and advanced technologies devoted to exploration of the electrochemistry and mechanism, nanostructured conjugated polymer-based electrodes will be of great scientific interest for future practical applications.

The emerging demand for electronic and transportation technologies has driven the development of rechargeable batteries with enhanced capacity storage. Especially, multivalent metal (Mg, Zn, Ca, and Al) and metal‐ion batteries have recently attracted considerable interests as promising substitutes for future large‐scale energy storage devices, due to their natural abundance and multielectron redox capability. These metals are compatible with nonflammable aqueous electrolytes and are less reactive when exposed in ambient atmosphere as compared with Li metals, hence enabling potential safer battery systems. Luckily, green and sustainable organic compounds could be designed and tailored as universal host materials to accommodate multivalent metal ions. Considering these advantages, effective approaches toward achieving organic multivalent metal and metal‐ion rechargeable batteries are highlighted in this Review. Moreover, organic structures, cell configurations, and key relevant electrochemical parameters are presented. Hopefully, this Review will provide a fundamental guidance for future development of organic‐based multivalent metal and metal‐ion rechargeable batteries.

A water-stable Li metal anode with water-stable lithium-conducting glass ceramics, normalLi1+x+ynormalTi2−xnormalAlxnormalSiynormalP3−ynormalO12 (LTAP), and a lithium-conducting polymer electrolyte, PEnormalO18Li(CnormalF3SnormalO2)2N (PEnormalO18LiTFSI) , was proposed as the lithium anode for lithium–air batteries with an aqueous solution at the air electrode. LTAP was unstable when in direct contact with Li metal, and the cell resistance of Li∕LTAP∕Li rapidly increased as a function of the contact time. The Li∕PEnormalO18LiTFSI∕LTAP∕PEnormalO18LiTFSI∕Li symmetrical cell showed no change in the total resistance (around 800Ωcm2 at 60°C ) over a period of 1month . The PEnormalO18LiTFSI membrane served as a protective interlayer to suppress the reaction between the water-stable glass ceramics LTAP and Li metal effectively. The Li∕PEnormalO18LiTFSI ∕LTAP∕aqueous LiCl∕Pt air cell showed a stable open-circuit voltage of 3.70V at 60°C for 2months . The open-circuit voltage was comparable with that calculated from the cell reaction of 2Li+1∕2normalO2+normalH2O=2LiOH . The cell exhibited a favorable discharge and charge performance at 0.25mAcm−2 and 60°C .

Different organic electrode materials in lithium-ion batteries are divided into three types: positive electrode materials, negative electrode materials, and bi-functional electrode materials, and are further discussed.

Organic n‐type materials (e.g., fullerene derivatives, naphthalene diimides (NDIs), perylene diimides (PDIs), azaacene‐based molecules, and n‐type conjugated polymers) are demonstrated as promising electron transport layers (ETLs) in inverted perovskite solar cells (p–i–n PSCs), because these materials have several advantages such as easy synthesis and purification, tunable frontier molecular orbitals, decent electron mobility, low cost, good solubility in different organic solvents, and reasonable chemical/thermal stability. Considering these positive factors, approaches toward achieving effective p–i–n PSCs with these organic materials as ETLs are highlighted in this Review. Moreover, organic structures, electron transport properties, working function of electrodes caused by ETLs, and key relevant parameters (PCE and stability) of p–i–n PSCs are presented. Hopefully, this Review will provide fundamental guidance for future development of new organic n‐type materials as ETLs for more efficient p–i–n PSCs.