Ni-based metal organic frameworks (Ni-MOFs) with unique hierarchical hollow ball-in-ball nanostructure were synthesized by solvothermal reactions. After successive carbonization and oxidation treatments, hierarchical NiO/Ni nanocrystals covered with a graphene shell were obtained with the hollow ball-in-ball nanostructure intact. The resulting materials exhibited superior performance as the anode in lithium ion batteries (LIBs): they provide high reversible specific capacity (1144 mAh/g), excellent cyclability (nearly no capacity loss after 1000 cycles) and rate performance (805 mAh/g at 15 A/g). In addition, the hierarchical NiO/Ni/Graphene composites demonstrated promising performance as anode materials for sodium-ion batteries (SIBs). Such a superior lithium and sodium storage performance is derived from the well-designed hierarchical hollow ball-in-ball structure of NiO/Ni/Graphene composites, which not only mitigates the volume expansion of NiO during the cycles but also provides a continuous highly conductive graphene matrix to facilitate the fast charge transfer and form a stable SEI layer.

Metal Organic Frameworks Derived Hierarchical Hollow NiO/Ni/Graphene Composites for Lithium and Sodium Storage

https://doi.org/10.1016/j.xinn.2022.100281

Metal-organic framework nanocrystal-derived hollow porous materials: Synthetic strategies and emerging applications

Supercapattery devices have grasped attention due to their remarkable specific energy (Es) without affecting their specific power (Ps), which is significantly higher compared to batteries and supercapacitors (SCs). In contrast to the traditional electric double layer capacitors (EDLCs) and pseudocapacitors (PCs), supercapattery devices have shown larger specific capacitance. Metal oxides, sulfides, phosphates, and metal-organic frameworks (MOFs) based materials have been extensively utilized for the advancement of hybrid energy storage devices (HESDs). Currently the challenges faced by this technology, is to improve the energy density without compromising the power density. The advantage of two merged technologies (battery and supercapacitor (SC)) into a single system, delivered tremendous power from capacitive components while high specific energy from battery grade material (BGM). This review covers the most recent improvements in vastly used electrode materials, with significant capacity as well as long cyclic life for high-performance supercapattery devices. Furthermore, this study aims to elaborate the electrochemical performance of the metal oxides, sulfides, phosphates, and MOFs for energy storage applications. 

Supercapattery: Merging of battery-supercapacitor electrodes for hybrid energy storage devices

Metal organic frameworks (MOFs) have been widely researched and applied in many fields. However, the poor electrical conductivity of many traditional MOFs greatly limits their application in electrochemistry, especially in energy storage. Benefited from the full charge delocalization in the atomical plane, conductive MOFs (c-MOFs) exhibit good electrochemical performance. Besides, unlike graphene, c-MOFs are provided with 1D cylindrical channels, which can facilitate the ion transport and enable high ion conductivity. Transition-metal oxides (TMOs) are promising materials with good electrochemical energy storage performance due to their excellent oxidation-reduction activity. When composited with TMOs, the c-MOFs can significantly improve the capacitance and rate performance. In this work, for the first time, we designed serial MnO2@Ni-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) nanoarrays with different lengths and explored how the lengths influence the electrochemical energy storage performance. By taking advantage of the high redox activity of MnO2 and the excellent electron and ion conductivity in Ni-HHTP, when assembled as the positive electrode material in an aqueous asymmetric supercapacitor, the device displays high energy density, outstanding rate performance, and superior cycle stability. We believe that the results of this work would provide a good prospect for developing other c-MOF composites as a potential class of electrode materials in energy storage and conversion.

When Conductive MOFs Meet MnO2: High Electrochemical Energy Storage Performance in an Aqueous Asymmetric Supercapacitor.

Fabrication of hollow MnFe2O4 nanocubes assembled by CoS2 nanosheets for hybrid supercapacitors

Hollow nanostructured materials are suitable for electrochemical reactions because of their unique internal cavity and short transport path. Carbon-based nanomaterials, including simplex carbon materials, heteroatom-doped carbon materials, carbon-transition metal nanoparticle composites, and carbon-transition metal compound composites, are promising electrode materials because of their high conductivity and stable structure. Hollow carbon-based nanomaterials, which possess the features of the aforementioned materials, have become a research hotspot in electrochemical energy storage and electrocatalysis. The excellent characteristics of metal–organic frameworks (MOFs) make them an ideal material for constructing hollow carbon-based nanomaterials. In this article, the process of preparing MOF-derived hollow carbon-based materials and their applications in electrochemical energy storage and electrocatalysis are reviewed. First, the various methods for preparing MOF-derived hollow carbon-based materials are introduced, and the characteristics of each method are analyzed. Second, the applications of MOF-derived hollow carbon-based materials in the oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, lithium-ion batteries, sodium-ion batteries, lithium–sulfur batteries, and supercapacitors are analyzed and summarized. Finally, research directions for further development of MOF-derived hollow carbon-based materials are proposed.

Design of hollow carbon-based materials derived from metal–organic frameworks for electrocatalysis and electrochemical energy storage

The introduction of high-entropy into Prussian blue analogues (PBAs) has yet to attract attention in the field of lithium-sulfur battery materials. Herein, we systematically synthesize a library of PBAs from binary to high-entropy by a facile coprecipitation method. The coordination environment in PBAs is explored by X-ray absorption fine structure spectroscopy, which together with elemental mapping confirm the successful introduction of all metals. Importantly, electrochemical tests demonstrate that high-entropy PBA can serve as polysulfide immobilizer to inhibit shuttle effect and as catalyst to promote polysulfides conversion, thereby boosting its outstanding performance. Additionally, a variety of nano cubic metal oxides from binary to senary are fabricated by using PBAs as sacrificial precursors. We believe that a wide range of new materials obtained from our coprecipitation and pyrolysis methodology can promote further developments in research on PBA systems and sulfur hosts.

High-Entropy Prussian Blue Analogues and Their Oxide Family as Sulfur Hosts for Lithium-Sulfur Batteries.

Heat treatment-induced Co3+ enrichment in CoFePBA to enhance OER electrocatalytic performance

Metal−organic frameworks (MOFs) are neo‐type porous materials synthesized via organic ligands and metal ions, which have drawn much attention due to their unparalleled advantages such as high specific surface area, large and clear pore structures, and uniformly distributed active sites. In these years, modified MOFs are regarded as kinds of materials with excellent electrochemical properties, that overcome poor conductivity and stability of original MOFs and narrow the gap between the basic science of MOFs and their future applications. At the same time, it also provides an opportunity to elaborate the synergistic effect of the synthesis strategy of modified MOFs on the performance. This review focuses on the synthesis, structure characterization, and electrochemical adhibition of modified MOFs and discusses the challenges and application prospects of modified MOFs in energy storage and conversion.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/sstr.202100200

Wenhui Hu

Papers

Design of hollow carbon-based materials derived from metal–organic frameworks for electrocatalysis and electrochemical energy storage

When Conductive MOFs Meet MnO2: High Electrochemical Energy Storage Performance in an Aqueous Asymmetric Supercapacitor.

High-Entropy Prussian Blue Analogues and Their Oxide Family as Sulfur Hosts for Lithium-Sulfur Batteries.

Heat treatment-induced Co3+ enrichment in CoFePBA to enhance OER electrocatalytic performance

Modified Metal−Organic Frameworks for Electrochemical Applications