aromatic groups, which via columnar π-π stacking order into a periodic 3D structure (Scheme S1, Supporting Information). Their modular construct and ordered porosity makes them find use in diverse applications Here we are seeking application of 2D COFs in metal-ion batteries, which are typically made of electrodes with layered structures, for example, graphite as anode and LiCoO 2 as cathode. Owing to their graphite resembling structure, COF can serve as anode. Since their initial discovery, many 2D materials with comparable layered structures have been explored as lithium insertion-deinsertion materials. [28][29][30][31][32][33][34][35][36][37][38][39] Some of the highly desirable characteristics of a superior anode material include moderate to high surface accessibility to ensure maximum charge storage per unit area, and the other is the hierarchical porosity for favorable kinetics. Exfoliation enhances surface accessibility and active site creation in such 2D materials. [40][41][42][43][44][45][46][47][48] In this regard, COFs could have much more to offer. [49][50][51] Exfoliation in any 2D material is largely dependent on the interlayer forces holding them. Typically, the COF layers are held together by interlayer π-π interactions or in some cases via additional hydrogen bonding. [52,53] However, unlike graphite, the layers of COF are not built from fused aromatic rings. In their optimized Covalent organic framework (COF) can grow into self-exfoliated nanosheets. Their graphene/graphite resembling microtexture and nanostructure suits electrochemical applications. Here, covalent organic nanosheets (CON) with nanopores lined with triazole and phloroglucinol units, neither of which binds lithium strongly, and its potential as an anode in Li-ion battery are presented. Their fibrous texture enables facile amalgamation as a coin-cell anode, which exhibits exceptionally high specific capacity of ≈720 mA h g −1 (@100 mA g −1 ). Its capacity is retained even after 1000 cycles. Increasing the current density from 100 mA g −1 to 1 A g −1 causes the specific capacity to drop only by 20%, which is the lowest among all high-performing anodic COFs. The majority of the lithium insertion follows an ultrafast diffusion-controlled intercalation (diffusion coefficient, D Li + = 5.48 × 10 −11 cm 2 s −1 ). The absence of strong Liframework bonds in the density functional theory (DFT) optimized structure supports this reversible intercalation. The discrete monomer of the CON shows a specific capacity of only 140 mA h g −1 @50 mA g −1 and no sign of lithium intercalation reveals the crucial role played by the polymeric structure of the CON in this intercalation-assisted conductivity. The potentials mapped using DFT suggest a substantial electronic driving-force for the lithium intercalation. The findings underscore the potential of the designer CON as anode material for Li-ion batteries. Lithium Storage

A covalent organic framework (COF), built from light atoms with a graphitic structure, could be an excellent anodic candidate for lightweight batteries, which can be of use in portable devices. But to replace the commercial graphite anode, they need more Li‐interactive sites/unit‐cell and all such sites should be made to participate. The compromise made in the volumetric density to gain the gravimetric advantage should be minimal. Exfoliation enhances surface/functional group accessibility yielding high capacity and rapid charge storage. A chemical strategy for simultaneous exfoliation and increase of Li‐loving active‐pockets can deliver a lightweight Li‐ion battery (LIB). Here, anthracene‐based COFs are chemically exfoliated into few‐layer‐thick nanosheets using maleic anhydride as a functionalizing exfoliation agent. It not only exfoliates but also introduces multiple Li‐interactive carbonyl groups, leading to a loading of 30 Li/unit‐cell (vs one Li per C6). The exfoliation enhances the specific capacity by ≈4 times (200–790 mAh g−1 @100 mA g−1). A realistic full‐cell, made using the exfoliated COF against a LiCoO2 cathode, delivers a specific capacity of 220 mAh g−1 over 200 cycles. The observed capacity stands highest among all organic polymers. For the first report of a COF derived full‐cell LIB, this is a windfall.

Lowering the LUMO levels of an anodic COF through the incorporation of N-rich modules favors electron accumulation on it, which sets up an electronic drive for the Na⁺ ions to enter the anode from the electrolyte. The optimal framework⋯Na⁺ interactions delivers excellent rate-performance.

Over the past decade, flexible and wearable microelectronic devices and systems have gained significant importance. Because portable power source is an essential need of such wearable devices, currently there is considerable research emphasis on the development of planar interdigitated micro energy -torage devices by employing diverse precursor materials to obtain functional materials (functional carbon, oxides, etc.) with the desirable set of properties. Herein we report for the first time the use of metal organic framework (MOF) and zeolitic imidazolate framework (ZIF-67) for high-wavelength photothermal laser direct writing of metal-decorated, heteroatom-doped, porous few-layer graphene electrodes for microsupercapacitor application. We argue that the specific attributes of MOF as a precursor and the high-wavelength laser writing approach (which creates extremely high localized and transient temperature (>2500 °C) due to strong absorption by lattice vibrations) are together responsible for the peculiar interesting properties of the carbon material thus synthesized, thereby rendering extremely high cycling stability to the corresponding microsupercapacitor device. Our device exhibits near 100% retention after 200 000 cycles as well as stability under 150° bending.

Owing to an unmatched combination of power and energy density along with cyclic stability, the Li-ion battery has qualified itself to be the highest performing rechargeable battery. Taking both transportable and stationary energy storage requirements into consideration, Li-ion batteries indeed stand tall in comparison to any other existing rechargeable battery technologies. However, graphite, which is still one of the best performing Li-ion anodes, has specific drawbacks in fulfilling the ever-increasing energy and power density requirements of the modern world. Therefore, further research on alternative anode materials is absolutely essential. Equally important is the search for and enhanced use of right earth abundant materials for battery electrodes so as to bring down the costs of the battery systems. In this spotlight article, we discuss the current research progress in the area of alternative anode materials for Li-ion battery, putting our own research work over the past several years into perspective. Starting from conversion anode systems like oxides and sulfides, to insertion cum alloying systems like transition metal carbides, to molecularly engineered open framework systems like metal organic frameworks (MOFs), covalent organic frameworks (COFs), and organic–inorganic hybrid perovskites (OIHPs), this spotlight provides a complete essence of the recent developments in the area of alternative anodes. The possible and potential impact of these new anode materials is detailed and discussed here.