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On the basis of the sustainable concept, organic compounds and carbon materials both mainly composed of light C element have been regarded as powerful candidates for advanced electrochemical energy storage (EES) systems, due to theie merits of low cost, eco-friendliness, renewability, and structural versatility. It is investigated that the carbonyl functionality as the most common constituent part serves a crucial role, which manifests respective different mechanisms in the various aspects of EES systems. Notably, a systematical review about the concept and progress for carbonyl chemistry is beneficial for ensuring in-depth comprehending of carbonyl functionality. Hence, a comprehensive review about carbonyl chemistry has been summarized based on state-of-the-art developments. Moreover, the working principles and fundamental properties of the carbonyl unit have been discussed, which has been generalized in three aspects, including redox activity, the interaction effect, and compensation characteristic. Meanwhile, the pivotal characterization technologies have also been illustrated for purposefully studying the related structure, redox mechanism, and electrochemical performance to profitably understand the carbonyl chemistry. Finally, the current challenges and promising directions are concluded, aiming to afford significant guidance for the optimal utilization of carbonyl moiety and propel practicality in EES systems.
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Given the inherent features of open tunnel-like structures, moderate lithiation potential (1.0-3.0 V vs Li/Li+), and reversible redox couples (Nb5+/Nb4+ and Nb4+/Nb3+ redox couples), niobium-based oxides with Wadsley-Roth crystallographic shear structure are promising anode materials. However, their practical rate capability and cycling stability are still hindered by low intrinsic electronic conductivity and structural stability. Herein, ultrathin carbon-confined Nb12O29 materials with rich oxygen vacancies (Nb12O29-x@C) were designed and synthesized to address above-mentioned challenges. Computational simulations combined with experiments reveal that the oxygen vacancies can regulate the electronic structure to increase intrinsic electronic conductivity and reduce the Li+ diffusion barrier. Meanwhile, the carbon coating can enhance structural stability and further improve the electronic conductivity of the Nb12O29 material. As a result, the as-prepared Nb12O29-x@C exhibits high reversible capacity (226 mAh g-1 at 0.1 A g-1), excellent high-rate performance (83 mAh g-1 at 5.0 A g-1), and durable cycling life (98.1% capacity retention at 1.0 A g-1 after 3000 cycles). The lithium storage mechanism and structural stability of Nb12O29-x@C were also revealed by in situ X-ray diffraction (XRD), ex situ X-ray photoelectron spectroscopy (XPS), and ex situ Raman spectroscopy. When applied as the anode of lithium-ion capacitors (LICs), the as-built LIC achieves high energy density (72.4 Wh kg-1) within the voltage window of 0.01-3.5 V, demonstrating the practical application potential of the Nb12O29-x@C materials.
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HIGHLIGHTS: Interfacial bonding strategy has been successfully applied to address the high overpotential issue of sacrificial additives, which reduced the decompositon potential of Na2C2O4 from 4.50 to 3.95 V. Ultra-low-dose technique assisted commercial sodium ion capacitor (AC//HC) could deliver a remarkable energy density of 118.2 Wh kg-1 as well as excellent cycle stability. In-depth decomposition mechanism of sacrificial compound and the relative influence after pre-metallation were revealed by advanced in situ and ex situ characterization approaches. Sacrificial pre-metallation strategy could compensate for the irreversible consumption of metal ions and reduce the potential of anode, thereby elevating the cycle performance as well as open-circuit voltage for full metal ion capacitors (MICs). However, suffered from massive-dosage abuse, exorbitant decomposition potential, and side effects of decomposition residue, the wide application of sacrificial approach was restricted. Herein, assisted with density functional theory calculations, strongly coupled interface (M-O-C, M = Li/Na/K) and electron donating group have been put forward to regulate the band gap and highest occupied molecular orbital level of metal oxalate (M2C2O4), reducing polarization phenomenon and Gibbs free energy required for decomposition, which eventually decrease the practical decomposition potential from 4.50 to 3.95 V. Remarkably, full sodium ion capacitors constituted of commercial materials (activated carbon//hard carbon) could deliver a prominent energy density of 118.2 Wh kg-1 as well as excellent cycle stability under an ultra-low dosage pre-sodiation reagent of 15-30 wt% (far less than currently 100 wt%). Noteworthily, decomposition mechanism of sacrificial compound and the relative influence on the system of MICs after pre-metallation were initially revealed by in situ differential electrochemical mass spectrometry, offering in-depth insights for comprehending the function of cathode additives. In addition, this breakthrough has been successfully utilized in high performance lithium/potassium ion capacitors with Li2C2O4/K2C2O4 as pre-metallation reagent, which will convincingly promote the commercialization of MICs.
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The low oxidation potential of a pre-sodiation cathode additive intrinsically prevents decomposition of the electrolyte. Although the introduction of electron-donating substitution reduces the oxidation potential, the additional molecular weight restricts the output capacity. Herein, as theroretically predicted, the electrochemical oxidation potential of sodium carboxylate is manipulated by the electronic effect and regiochemistry of the functionality, in which the stronger electron-donating substituent, p-π conjugation, and optimized regiochemistry can dramatically lead to the lower potential originated from the elevation of the highest occupied molecular orbital level. Thus, benefiting from the para-NH2 unit accompanied by a conjugated aromatic architecture, molecularly engineered sodium para-aminobenzoate (PABZ-Na) presents a reduced oxidation plateau of 3.45 V. Triggered by the positive compensation merit, sodium-based electrochemical storage systems manifest excellent electrochemical performances. This breakthrough sheds light into the correlation between the electronic effect of the functional group and the oxidation potential of the organic additive, affording in-depth insights into the fundamental guidance of pre-sodiation chemistry.
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Nowadays sodium-based energy storage systems (Na-based ESSs) have been widely researched as it possesses the possibility to replace traditional energy storage media to become next generation energy storage system. However, due to the irreversible loss of sodium ions in the first cycle, development of Na-based ESSs is limited. Presodiation, as a strategy of adding excess sodium ions to the system in advance, accomplishes the enhancement of electrochemical performance. In this minireview, different presodiation strategies applied in sodium-based energy storage systems will be summarized in detail, their functions and corresponding mechanisms will be discussed as well. Furthermore, the current novel application of presodiation method in other aspects of Na-based ESSs will be mentioned additionally. At last, in the view of present research status of presodiation, issues that can be mitigated are put forward and guidelines are given on how to deliberate in-depth presodiation technology in the future, dedicating to promote the further development of Na-based ESSs.
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The use of a sacrificial cathode additive as a pre-metallation method could ensure adequate metal sources for advanced energy storage devices. However, this pre-metallation technique suffers from the precise regulation of decomposition potential of additive. Herein, a molecularly compensated pre-metallation (Li/Na/K) strategy has been achieved through Kolbe electrolysis, in which the electrochemical oxidation potential of a metal carboxylate is manipulated by the bonding energy of the oxygen-metal (O-M) moiety. The electron-donating effect of the substituent and the low charge density of the cation can dramatically weaken the O-M bond strength, further bringing out the reduced potential. Thus, sodium acetate exhibits a superior pre-sodiation feature for sodium-ion battery accompanied with a large irreversible specific capacity of 301.8â mAh g-1 , remarkably delivering 70.6 % enhanced capacity retention in comparison to the additive-free system after 100â cycles. This methodology has been extended to construct a high-performance lithium-ion battery and a lithium/sodium/potassium-ion capacitor.
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Correction for 'Highly stable zinc metal anode enabled by oxygen functional groups for advanced Zn-ion supercapacitors' by Kangyu Zou et al., Chem. Commun., 2021, 57, 528-531, DOI: 10.1039/D0CC07526D.
RESUMEN
Bismuthene was prepared via the oxidation of Zintl clusters by electrochemical cathodic corrosion. It was found that the conversion of Zintl clusters from Bi22- to Bi2 occurred in the electrolyte having short alkyl chains due to the faster kinetics of highly reactive carbocation. Considering that c-Na3Bi exists in a wide voltage range, monitored by in situ XRD, a new wide peak for the as-obtained bismuthene in the CV curve was noticed, which benefits the improvement of electrochemical performances.
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The rate-determining process for sodium storage in TiO2 is greatly depending on charge transfer happening in the electrode materials owing to its inferior diffusion coefficient and electronic conductivity. Apart from reducing the diffusion distance of ion/electron, the increasement of ionic/electronic mobility in the crystal lattice is also very important for charge transport. Here, an oxygen vacancy (OV) engineering assisted in high-content anion (S/Se/P) doping strategy to enhance charge transfer kinetics for ultrafast sodium-storage performance is proposed. Theoretical calculations indicate that OV-engineering evokes spontaneous S doping into the TiO2 phase and achieves high dopant concentration to bring about impurity state electron donor and electronic delocalization over S occupied sites, which can largely reduce the migration barrier of Na+. To realize the speculation, high-content anion doped anatase TiO2/C composites (9.82 at% for S in A-TiO2-x-S/C) are elaborately designed. The optimized A-TiO2-x-S/C anode exhibits extraordinarily high-rate capability with 209.6 mAh g-1 at 5000 mA g-1. The assembled sodium ion capacitors deliver an ultrahigh energy density of 150.1 Wh kg-1 at a power density of 150 W kg-1 when applied as anode materials. This work provides a new strategy to realize high content anion doping concentration, and enhances the charge transfer kinetics for TiO2, which delivers an efficient approach for the design of electrode materials with fast kinetic.
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Konjac glucomannan (KGM) featuring abundant oxygen functional groups has been elaborately designed to enhance Zn reversibility. Importantly, -OH and C[double bond, length as m-dash]O groups as active sites could redistribute the Zn2+ concentration field and modulate the plating/stripping rate, further enabling uniform Zn deposition without dendrite growth. The Zn@KGM anode enables an advanced Zn-ion supercapacitor to deliver an impressive rate performance and cycling stability (up to 5000 cycles accompanied by a coulombic efficiency of 99.8%).
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Tuning hierarchical pore structure of carbon materials is an effective way to achieve high energy density under high power density of carbon-based supercapacitors. However, at present, most of methods for regulating pores of carbon materials are too complicated to be achieved. In this work, a durian shell derived porous carbon (DSPC) with abundant porous is prepared through chemical activation as a defect strategy. Hierarchical porous structure can largely enhance the transfer rate of electron/ion. Furthermore, DSPC with multiple porous structure exhibits excellent properties when utilized as electrode materials for electric double layer capacitors (EDLCs), delivering a specific capacitance of 321 F g-1 at 0.5 A g-1 in aqueous electrolyte. Remarkably, a high energy density of 27.7 Wh kg-1 is obtained at 675 W kg-1 in an organic two-electrode device. And large capacity can be remained even at high charge/discharge rate. Significantly, hierarchical porous structure allows efficient ion diffusion and charge transfer, resulting in a prominent cycling stability. This work is looking forward to providing a promising strategy to prepare hierarchical porous carbon-based materials for supercapacitors with ultrafast electron/ion transport.
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Lithium ion capacitors (LICs) are regarded as one of the most promising energy storage devices since they can bridge the gap between lithium ion batteries and supercapacitors. However, the mismatches in specific capacity, high-rate behavior, and cycling stability between the two electrodes are the most critical issues that need to be addressed, severely limiting the large energy density and long cycling life of LICs while delivering high-power density output. Herein, quinone and ester-type oxygen-modified carbon has been successfully obtained by chemical activation with alkali, which is beneficial to the absorption of PF6- together with lithium ions, which would largely improve the electrode kinetics. In particular, the cathode capacity is considerably enhanced with the increase in the amount of oxygen functional groups. Moreover, for the full carbon LIC device, an energy density of 144 W h kg-1 is exhibited at the power density of 200 W kg-1. Surprisingly, even after 10 000 cycles at 20 000 W kg-1, a capacity retention of 70.8% is successfully achieved. These remarkable results could be ascribed to the enhancement of cathode capacity and the acceleration of anode kinetics. Furthermore, the density functional theory (DFT) calculations prove that the oxygen functional groups can deliver enhanced electrochemical activity for lithium storage through surface-induced redox reactions. This elaborate study may open an avenue for resolving the issues with the electrode materials of LICs and deepen the understanding on the surface engineering strategies for incorporating oxygen-functional groups.
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The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors, limiting the advancement of lithium ion capacitors (LICs). Here, an orientated-designed pore size distribution (range from 0.5 to 200 nm) and graphitization engineering strategy of carbon materials through regulating molar ratios of Zn/Co ions has been proposed, which provides an effective platform to deeply evaluate the capacitive behaviors of carbon cathode. Significantly, after the systematical analysis cooperating with experimental result and density functional theory calculation, it is uncovered that the size of solvated PF6- ion is about 1.5 nm. Moreover, the capacitive behaviors of carbon cathode could be enhanced attributed to the controlled pore size of 1.5-3 nm. Triggered with synergistic effect of graphitization and appropriate pore size distribution, optimized carbon cathode (Zn90Co10-APC) displays excellent capacitive performances with a reversible specific capacity of ~ 50 mAh g-1 at a current density of 5 A g-1. Furthermore, the assembly pre-lithiated graphite (PLG)//Zn90Co10-APC LIC could deliver a large energy density of 108 Wh kg-1 and a high power density of 150,000 W kg-1 as well as excellent long-term ability with 10,000 cycles. This elaborate work might shed light on the intensive understanding of the improved capacitive behavior in LiPF6 electrolyte and provide a feasible principle for elaborate fabrication of carbon cathodes for LIC systems.
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Metal-organic frameworks (MOFs), as an important kind of porous inorganic-organic hybrid materials with inherent outstanding physicochemistry characteristics, can be widely applied as versatile precursors for the facile preparation of functional MOF-derived materials. However, there are plenty of sophisticated factors during the synthetic process, which is far from reaching the goal of effectively controlling the nature of MOF-derived materials (such as the composition, morphology and surface area). Therefore, it is urgently necessary to develop regular protocols and concepts for controllable syntheses of MOF-derived materials. In this minireview, we mainly summarize and analyze complicated factors in the fabrication of MOF-derived materials according to recently reported literatures, and this provides a new insight into the rational design and syntheses of MOF-derived materials.
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In this work, five new cadmium metal-organic frameworks (Cd-MOFs 1-5) have been synthesized from solvothermal reactions of Cd(NO3 )2 â 4 H2 O with isophthalic acid and 1,4-bis(imidazol-1-yl)-benzene under different solvent systems of CH3 OH, C2 H5 OH, (CH3 )2 CHOH, DMF, and N-methyl-2-pyrrolidone (NMP), respectively. Cd-MOF 1 shows a 3D diamondoid framework with 1D rhombic and hexagonal channels, and the porosity is 12.9 %. Cd-MOF 2 exhibits a 2D (4,4) layer with a 1D parallelogram channel and porosity of 23.6 %. Cd-MOF 3 has an 8-connected dense network with the Schäfli symbol of [424 â 64 ] based on the Cd6 cluster. Cd-MOFs 4-5 are isomorphous, and display an absolutely double-bridging 2D (4,4) layer with 1D tetragonal channels and porosities of 29.2 and 28.2 %, which are occupied by DMF and NMP molecules, respectively. Followed by the calcination-thermolysis procedure, Cd-MOFs 1-5 are employed as precursors to prepare MOF-derived porous carbon materials (labeled as PC-me, PC-eth, PC-ipr, PC-dmf and PC-nmp), which have the BET specific surface area of 23, 51, 10, 122, and 96â m2 g-1 , respectively. The results demonstrate that the specific surface area of PCs is tuned by the porosity of Cd-MOFs, where the later is highly dependent on the solvent. Thereby, the specific surface area of PCs could be adjusted by the solvent used in the synthese of MOF precusors. Significantly, PCs have been further activated by KOH to obtain activated carbon materials (APCs), which possess even higher specific surface area and larger porosity. After a series of characterization and electrochemical investigations, the APC-dmf electrode exhibits the best porous properties and largest specific capacitances (153â F g-1 at 5â mV s-1 and 156â F g-1 at 0.5â Ag-1 ). Meanwhile, the APC-dmf electrode shows excellent cycling stability (ca. 84.2 % after 5000 cycles at 1â Ag-1 ), which can be applied as a suitable electrode material for supercapacitors.
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Herein three novel cobalt metal-organic frameworks (Co-MOFs) with similar ingredients, [Co(bib)(o-bdc)]∞ (1), [Co2(bib)2(m-bdc)2]∞ (2), and {[Co(bib)(p-bdc)(H2O)](H2O)0.5}∞ (3), have been synthesized from the reaction of cobalt nitrate with 1,4-bis(imidazol-1-yl)benzene (bib) and structure-related aromatic acids (1,2-benzenedicarboxylic acid = o-bdc, 1,3-benzenedicarboxylic acid = m-bdc, and 1,4-benzenedicarboxylic acid = p-bdc) by the solvothermal method. It is aimed to perform systematic research on the relationship among the conformation of benzoate acid, lattice dimension of Co-MOF, and pore diameter of MOF-derived carbon composite. Through the precursor strategy, Co-MOFs 1-3 have been utilized to synthesize porous cobalt@carbon nanotube composites (Co@CNTs). After the in situ gas-sulfurization, secondary composites CoS2@CNTs were successfully obtained, which kept similar morphologies of corresponding Co@CNTs without destroying previous highly dispersed structures. Co-MOFs and two series of composites (Co@CNTs and CoS2@CNTs) have been well characterized. Topology and Brunauer-Emmett-Teller analyses elucidate that the bdc2- ion could control the pore diameters of MOF-derived carbon composites by adjusting the lattice dimension of Co-MOFs. The systematic studies on electrochemical properties demonstrate that (p)-CoS2@CNT possesses hierarchical morphology, moderate specific surface area, proper pore diameter distribution, and high graphitization, which lead to remarkable specific capacitances (839 F g-1 at 5 mV s-1 and 825 F g-1 at 0.5 A g-1) in 2 M potassium hydroxide solution. In addition, the (p)-CoS2@CNT electrode exhibits good electrochemical stability and still retains 82.9% of initial specific capacitance at the current density of 1 A g-1 after 5000 cycles.
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Herein, four new cadmium metal-organic frameworks (Cd-MOFs), [Cd(bib)(bdc)]∞ (1), [Cd(bbib)(bdc)(H2 O)]∞ (2), [Cd(bibp)(bdc)]∞ (3), and [Cd2 (bbibp)2 (bdc)2 (H2 O)]∞ (4), have been constructed from the reaction of Cd(NO3 )2 â 4 H2 O with 1,4-benzenedicarboxylate (H2 bdc) and structure-related bis(imidazole) ligands (1,4-bis(imidazol-1-yl)benzene (bib), 1,4-bis(benzoimidazol-1-yl)benzene (bbib), 4,4'-bis(imidazol-1-yl)biphenyl (bibp), and 4,4'-bis(benzoimidazol-1-yl)biphenyl (bbibp)) under solvothermal conditions. Cd-MOF 1 shows a 2D (4,4) lattice with parallel interpenetration, whereas 2 displays an interesting 3D interpenetrating dia network, 3 exhibits an unusual 3D interpenetrating dmp network, and 4 presents a 3D self-catenated pillar-layered framework with a Schäfli symbol of [43 â 63 ]2 â [46 â 616 â 86 ]. The structural diversity indicates that the backbone of the bis(imidazole) ligand (including the terminal group and spacer) plays a crucial role in the assembly of mixed-ligand frameworks. By using the pore-forming effect of cadmium vapor, for the first time we have utilized these Cd-MOFs as precursors to further prepare porous carbon materials (PCs) in a calcination-thermolysis procedure. These PCs show different porous features that correspond to the topological structures of Cd-MOFs. Significantly, it was found that the specific surface area and capacitance of PCs are tuned by the Cd/C ratio of the MOF. Furthermore, the as-synthesized PCs were processed with KOH to obtain activated porous carbon materials (APCs) with higher specific surface area and porosity, which greatly promoted the energy-storage capacity. After full characterization, we found that APC-bib displays the largest specific surface area (1290â m2 g-1 ) and total pore volume (1.37â cm3 g-1 ) of this series of carbon materials. Consequently, APC-bib demonstrates the highest specific capacitance of 164â F g-1 at a current density of 0.5â A g-1 , and also excellent retention of capacitance (≈89.4 % after 5000 cycles at 1â A g-1 ). Therefore, APC-bib has great potential as the electrode material in a supercapacitor.
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A peculiar copper metal-organic framework (Cu-MOF) was synthesized by a self-assembly method, which presents a 3-fold interpenetrating diamondoid net based on the square-planar Cu(II) node. Although it exhibits a high degree of interpenetration, the Cu-MOF still exhibits a one-dimensional channel, which provides a template for constructing porous materials through the "precursor" strategy. Furthermore, the explosive ClO4(-) ion, which resided in the channel, could induce the quick decomposition of organic ingredients and release a huge amount of gas, which is beneficial for the porosity of postsynthetic materials. Significantly, we first utilize this explosive MOF to prepare a series of Cu@C composites through the calcination-thermolysis method at different temperatures, which contain copper particles exhibiting various shapes and combinations with the carbon substrate. Considering the hole-forming effect of copper particles, Cu@C composites were etched by HCl to afford a sequence of hierarchically flower-like N-doped porous carbon materials (NPCs), which retain the original morphology of the Cu-MOF. Interestingly, NPC-900, originating from the calcination of the Cu-MOF at 900 °C, exhibits a more regular flower-like morphology, the largest specific surface area, abundant porosities, and multiple nitrogen functionalities. The remarkable specific capacitances are 138 F g(-1) at 5 mV s(-1) and 149 F g(-1) at 0.5 A g(-1) for the NPC-900 electrode in a 6 M potassium hydroxide aqueous solution. Moreover, the retention of capacitance remains 86.8% (125 F g(-1)) at 1 A g(-1) over 2000 cycles, which displays good chemical stability. These findings suggest that NPC-900 can be applied as a suitable electrode for a supercapacitor.
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In this work, three isomeric benzenedicarboxylates, 1,2-benzenedicarboxylic acid (o-H2bdc), 1,3-benzenedicarboxylic acid (m-H2bdc), and 1,4-benzenedicarboxylic acid (p-H2bdc) have been utilized as the ancillary ligands to perform a systematic study on the structural diversity of mixed-ligand frameworks. The solvothermal reactions of Co(NO3)2 with these aromatic acids and the primary ligand 4,4'-bis(imidazolyl)biphenyl (bibp) afford three novel coordination polymers, {[Co6(bibp)3(o-bdc)6(H2O)](CH3CN)1.5}∞ (1), [Co(bibp)(m-bdc)]∞ (2), and [Co(bibp)(p-bdc)]∞ (3). Owing to the different orientations of the carboxylate groups, the benzenedicarboxylates adopt various bridging modes to connect the Co(II) ions into a series of 1D carboxylateâ©cobalt architectures based on the 1D chain, binuclear and single-ion magnetic units, respectively. These 1D architectures are further decorated by the bibp ligand to afford a 1D belt for , 2D double-bridging (4,4) sheet for 2, and an unusual 3D dmp framework for 3. Significantly in 3, three equivalent frameworks are interlocked with each other to represent an unprecedented three-fold interpenetrating dmp network. The structural diversity indicates that the benzenedicarboxylate plays an essential role in the assembly of mixed-ligand frameworks, and the orientation of the carboxylate group exerts an important influence on the nucleation, dimensionality and also interpenetration. Furthermore, the magnetic properties of 1 and 2 have been studied by fitting the experimental data as possible, and the magneto-structural correlation of 2 has also been well discussed. Importantly, CoO and Co3O4 were obtained from the controllable thermolysis of crystals of 1 via simple calcination treatment under different gas environments. The as-synthesized cobalt oxides display good crystallinity and appear as micro- or nanoparticles, which can be applied as supercapacitor electrodes as demonstrated by their energy storage performance in 2 M KOH electrolyte.