Compared to inorganic electrodes, organic materials are regarded as promising electrodes for lithium-ion batteries (LIBs) due to the attractive advantages of light elements, molecular-level structural design, fast electron/ion transferring, favorable environmental impacts, and flexible feature, etc. Not only specific capacities but also working potentials of organic electrodes are reasonably tuned by polymerization, electron-donating/withdrawing groups, and multifunctional groups as well as conductive additives, which have attracted intensive attention. However, organic LIBs (OLIBs) are also facing challenges on capacity loss, side reactions, electrode dissolution, low electronic conductivity, and short cycle life, etc. Many strategies have been applied to tackle those challenges, and many inspiring results have been achieved in the last few decades. In this review, we have introduced the basic concepts of LIBs and OLIBs, followed by the typical cathode and anode materials with various physicochemical properties, redox reaction mechanisms, and evolutions of functional groups. Typical charge−discharge behaviors and molecular structures of organic electrodes are displayed. Moreover, effective strategies on addressing problems of organic electrodes are summarized to give some guidance on the synthesis of optimized organic electrodes for practical applications of OLIBs.

Two metal-organic frameworks constructed from nanosized Cu(20) and Cu(30) wheels have been obtained under hydrothermal conditions based on 1,2,3-triazole and 1-H-1,2,3-benzotriazole, respectively. Crystal structure analysis shows that their differences in the size and nuclearity of Cu(20) and Cu(30) wheels are attributed to the steric effect of ligands.

Four 3D POM-based silver coordination polymers, namely, [Ag17(ptz)11(PW12O40)2]n (1), [Ag17(ptz)11(PMo12O40)2]n (2), [Ag12(ptz)6(CN)2(SiW12O40)]n (3), and [Ag19(ptz)8(H2ptz)(H3ptz)(AgP5W30O110)·7H2O]n (4), have been obtained by solvothermal reaction of AgNO3 and 5-phenyl-1H-tetrazole (Hptz) ligand in the presence of four types of polyoxometalates. Structural analysis shows that four types of Ag(I)···π interactions, m-η(1), m/p-η(2), o/m-η(2), and o/m/p-η(3), were observed in compounds 1-4, depending on the polyoxometalates used. The in situ generated CN(-) ion in compound 3 shows unprecedented mixed σ and π bonding modes, similar to the C2(2-) ion in well-studied silver acetylides. For 4, the Na(+) ion in the Preyssler heteropolyoxoanion, [NaP5W30O110](14-), was exchanged by Ag(I) under solvothermal conditions, generating a novel [AgP5W30O110](14-) anion. In addition, the photoluminescence behavior of 1-4 was also investigated.

Metal sulfides are regarded as the most promising candidates for sodium-ion battery (SIB) anodes because of their merits of high theoretical capacity, stable redox reactions, and low-cost raw materials. However, low electronic conductivity, sluggish ionic diffusion, and unstable reaction interfaces have largely limited their practical applications. To tackle these problems, a special pomegranate structure, composed of many nitrogen-doped carbon-coated bimetallic sulfide nanoparticles (FeS/NiS@NCS), is deliberated designed. When used as the anode of SIBs, FeS/NiS@NCS has exhibited a high reversible capacity (668.7 mA h g–1 at 0.1 A g–1), a superior cycling stability (414.6 mA h g–1 with 86.7% capacity retention after 500 cycles at 1 A g–1), and a high rate capability (251 mA h g–1 at 5 A g–1). Moreover, when paired with the cathode material of carbon-coated Na3V2(PO4)2F3 (C-NVPF), the full cell delivers good cycle performances (65.07 mA h g–1 with 75.8% capacity retention after 100 cycles at 1 A g–1). Besides, the in situ X-ray diffraction technique was performed to analyze its structural evolution, confirming that the FeS/NiS@NCS anode undergoes a two-step reaction mechanism (first Na+ insertion process and then phase conversion reaction during the discharging process, conversion reaction, and ionic extraction during the charging process).

in situ X-ray diffraction (XRD), ionic codoping, Li 3 V 2 (PO 4 ) 3 , theoretical calculations, wide temperature range

Transition metal phosphides (TMPs) are perplexed by the low electronic/ionic conductivity, volume variations, and unstable reaction interfaces. To tackle these issues, herein, we have proposed a low‐temperature phosphorization strategy by reactions between Co‐based metal‐organic frameworks (MOF) and sodium dihydric hypophosphite to encapsulate monodisperse CoP nanoparticle (∼12 nm) into MOF‐derived hollow and porous carbon nanobox (CoP@PCB). Compared to bare CoP, such CoP@PCB electrode has shown remarkable electrochemical performance, which is highly ascribed to its robust structural feature, pre‐reserved voids, monodisperse CoP nanoparticles, and stable reaction interfaces, as well as fast reaction kinetics. Moreover, the good electrochemical properties of CoP@PCB//LiFePO4 full cells have demonstrated practical possibility. The formation of Co and Li3P as discharged products has corroborated the redox conversion reaction mechanism, as assessed by in‐situ X‐ray diffractions. The favorable function of the carbon shell in boosting both electronic conductivity and lowering diffusion energy barriers has been confirmed by theoretical calculations, demonstrating an important synergistic effect.