Search

The Rubik's cube PBA frameworks with infinite structural variations have been obtained by a simple coprecipitation method and exhibits enhanced cycling and rate performance when tested as the anode materials in alkali-ion batteries (LIBs, SIBs, and KIBs). More importantly, the storage mechanism of the Co-Zn PBA frameworks have also been explored by DFT, in-situ XRD, and XPS measurements. [Display omitted] • Successfully synthesized Rubik's Co-M PBAs and explored the storage mechanism of the anode in alkali-metal-ion batteries. PBA frameworks have stood out among metal–organic frameworks because of their easy preparation, excellent stability, porous structures, and rich redox properties. Unfortunately, their non-ideal conductivity and significant volume expansion during cycling prevent more widespread application in alkali-metal-ion (Li+, Na+, and K+) batteries. By changing the type and molar ratio of metal ions, Rubik's PBA frameworks with infinite structural variations were obtained in this study, just like the Rubik's cube undergoes infinite changes during the rotation. X-ray adsorption fine structure measurements have documented the existence and determined the coordination environment of the metal ions in the Rubik's PBA framework. Benefiting from the more stable Rubik's cube structures with diverse composition, enhanced conductivity, and greater adsorption capacity, the obtained Rubik's cubes CoM-PBA anodes, especially CoZn-PBA deliver the enhanced cycling and rate performance in all the alkali-metal-ion batteries. The findings are supported by density functional theory calculations. Ex-situ X-ray photoelectron spectroscopy, and in-situ X-ray diffraction measurements were undertaken to explore the storage mechanism of CoZn-PBA anodes. Our results further demonstrate that the Rubik's cube PBA framework-based materials could be widely applied in the field of alkali-metal-ion batteries. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks are recognized as active electrode materials for rechargeable batteries due to their structural diversity, abundant electrochemical active sites and large ion diffusion channels. Herein, nickel-terephthalic acid metal-organic frameworks (Ni-PTA MOFs) with different crystal and morphology structures are synthesized via a facile solvothermal method by simply adjusting the nature of solvent. Due to the fewest guest molecules and porous structure, the Ni-PTA resulting from the combinations of DMF and EtOH exhibits the comparatively higher chemical/thermal stability and shortened ion diffusion pathway. As a result, it exhibits a high discharge/charge capacity of 2196.4 and 1762.3 mAh g−1 at the first cycle and retains 1300 mAh g−1 after 50 cycles at 100 mA g−1 when tested as anode materials for Li-ion batteries. Even when the current density reaches 4000 mA g−1, it maintains a capacity of 452 mAh g−1. This work provides possibilities for regulating the crystal and morphology structure of MOFs as high performance anode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Co‐insertion of protons happens widely and enables divalent‐ion aqueous batteries to achieve high performances. However, detailed investigations and comprehensive understandings of proton co‐insertion are scarce. Herein, we demonstrate that proton co‐insertion into tunnel materials is determined jointly by interface derivation and inner diffusion: at the interface, hdrated Mg2+ has poor insertion kinetics, and therefore accumulates and hydrolyzes to produce protons; in the tunnels, co‐inserted/lattice H2O molecules block the Mg2+ diffusion while facilitate the proton diffusion. When monoclinic vanadium dioxide (VO2(B)) anode is tested in Mg(CH3COO)2 aqueous solution, the formation of Mg‐rich solid electrolyte interphase on the VO2(B) electrode and co‐insertion of derived protons are probed; in the tunnels, the diffusion energy barrier of Mg2++H2O is 2.7 eV, while that of the protons is 0.37 eV. Thus, protons dominate the subsequent insertion and inner diffusion. As a consequence, the VO2(B) achieves a high capacity of 257.0 mAh g−1 at 1 A g−1, a high rate retention of 59.1 % from 1 to 8 A g−1, and stable cyclability of 3000 times with a capacity retention of 81.5 %. This work provides an in‐depth understanding of the proton co‐insertion and may promote the development of rechargeable aqueous batteries. [ABSTRACT FROM AUTHOR]

Owing to the rich redox functionalities and numerous pore structure, metal‐organic frameworks (MOFs) are directly emerging as prospective electrode materials with special properties. In the present study, exotic and unique nanomaterials of copper‐based metal‐organic framework (Cu‐MOF‐74) were successfully prepared by coordination assembly of Cu (II) and 2,5‐dihydroxyterephthalic acid (DHTA) through the solvothermal route and served as anode materials for lithium‐ion batteries for the first time. The Cu MOF has a coral cluster‐like nanoporous morphology composed of hexagonal columns with a length of 3.0 μm and a radius of 132 nm. When tested as anode, it achieved a high reversible capability of 870.3 mA h g−1 at 100 mA g−1, remarkable rate performance (up to 1000 mA h g−1) and a long service life (300 cycles) in the dis‐/charge process. Such outstanding properties of the MOF anode may be mainly ascribed to the conjugated ligand moiety and the particular microstructural features. The results of this study provided insights for the rational design of primitive MOFs for advanced lithium storage. [ABSTRACT FROM AUTHOR]

A metal–organic framework based on a longer linear ligand was rationally designed and evaluated as a novel anode material for sodium-ion batteries. It delivered a high specific capacity of 269 mA h g−1 with a desired voltage plateau and demonstrated excellent capacity retention (79.0% after 1000 cycles). In addition, its reaction kinetics was also investigated in detail by performing cyclic voltammetry and a predominantly diffusion-controlled process was clearly revealed. [ABSTRACT FROM AUTHOR]

We report an air-PEDOT battery where an optimized oxidation level of the PEDOT anode was performed using a simple dedoping process, resulting in batteries with high stability in air. Some PEDOT:PSS chains were reduced to their neutral state, preserving their good electrical conductivity, by dipping the PEDOT:PSS films into mixtures of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and dimethyl sulfoxide (DMSO). Because of the neutral PEDOT chains are susceptible to being reoxidized in air, polyethyleneimine (PEI) was coated on these DMSO-DBU/PEDOT:PSS anodes to ensure their air stability and to maintain their low level of oxidation during the battery operation. The difference in the oxidation level between the dedoped PEDOT:PSS and pristine PEDOT:PSS electrodes produces an open circuit voltage of about 0.80 V almost constant by several days (around 30 days) in air. These batteries present discharge currents of ≈2 μA with an electrical load of 0.1 MΩ during 10 h of operation, output powers of ≈1.2 μW, using an electrical load of 265 kΩ, which is in the required range for powering wireless transceiver and sensors. [ABSTRACT FROM AUTHOR]