• Energy Research

The low electronic conductivity of organic electrode materials leads to sluggish reaction kinetics and inferior electrochemical performance of lithium-ion batteries. Herein, the conducting three-dimensional metal–organic framework (3D-MOF) (NBu 4 ) 2 Fe 2 (DHBQ) 3 was synthesized through a facile aqueous addition reaction. The intramolecular charge delocalization through the robust π–d conjugation between DHBQ ligands and Fe 3+ centers is favorable for long-range electron migration, resulting in high electronic conductivity of the 3D hollow (NBu 4 ) 2 Fe 2 (DHBQ) 3 . When applied as the cathode material, (NBu 4 ) 2 Fe 2 (DHBQ) 3 delivers a reversible capacity of 137.2 mA h g –1 at 10 mA g –1 and 95.2 mA h g –1 at 1000 mA g –1 . The capacity retention reached up to 91.4% after 350 cycles at 500 mA g –1 with about 100% Coulombic efficiency. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy tests reveal that the conjugated carbonyls of DHBQ organic linkers contribute the redox centers and undergo a 5e – reaction mechanism during charge and discharge processes. These excellent electrochemical performances could be attributed to the fast electron/ion migration kinetics because of high electronic conductivity and the hollow structure of (NBu 4 ) 2 Fe 2 (DHBQ) 3 . All the positive results could facilitate the implementation of conductive MOFs for energy conversion and storage acceleration.

The recent developments of amorphous material based heterostructures with disordered heterointerfaces for advanced rechargeable batteries are reviewed, focusing on the relation between material structure and electrochemical performance.

AbstractChemical doping is a powerful method to intrinsically tailor the electrochemical properties of electrode materials. Here, an interstitial boron‐doped tunnel‐type VO2(B) is constructed via a facile hydrothermal method. Various analysis techniques demonstrate that boron resides in the interstitial site of VO2(B) and such interstitial doping can boost the zinc storage kinetics and structural stability of VO2(B) cathode during cycling. Interestingly, we found that the boron doping level has a saturation limit peculiarity as proved by the quantitative analysis. Notably, the 2 at.% boron‐doped VO2(B) shows enhanced zinc ion storage performance with a high storage capacity of 281.7 mAh g−1 at 0.1 A g−1, excellent rate performance of 142.2 mAh g−1 at 20 A g−1, and long cycle stability up to 1000 cycles with the capacity retention of 133.3 mAh g−1 at 5 A g−1. Additionally, the successful preparation of the boron‐doped tunnel‐type α‐MnO2 further indicates that the interstitial boron doping approach is a general strategy, which supplies a new chance to design other types of functional electrode materials for multivalence batteries.