We herein demonstrate the fabrication of Mn- and Ni-based ultrathin metal–organic framework nanosheets with the same coordination mode (termed “Mn-UMOFNs” and “Ni-UMOFNs”, respectively) through an expedient and versatile ultrasonic approach and scrutinize their electrochemical properties as anode materials for rechargeable lithium batteries for the first time. The obtained Mn-UMOFNs with structure advantages over Ni-UMOFNs (thinner nanosheets, smaller metal-ion radius, higher specific surface area) exhibit high reversible capacity (1187 mAh g–1 at 100 mA g–1 for 100 cycles), excellent rate capability (701 mAh g–1 even at 2 A g–1), rapid Li+ diffusion coefficient (2.48 × 10–9 cm2 s–1), and a reasonable charge–discharge profile with low average operating potential at 0.4 V. On the grounds of the low-cost and environmental benignity of Mn metals and terephthalic acid linkers, our Mn-UMOFNs show alluring promise as a low-cost high-energy anode material for future LIBs. Furthermore, the lithiation–delithiation chemistry of Mn-UMOFNs was unequivocally studied by a combination of magnetic measurements, electron paramagnetic resonance, and synchrotron-based soft X-ray spectroscopy (O K-edge and Mn L-edge) experiments, the results of which substantiate that both the aromatic chelating ligands and the Mn2+ centers participate in lithium storage.Keywords: local environment; manganese; metal−organic framework; rehybridization; ultrathin nanosheets;

•We modify the 180 composite pulses for spin 1/2 for overtone excitation.•The bandwidth of composite pulses can be tailored by adjusting the pulse width.•COM-R5m and COM-R6m allow sufficient excitation bandwidth when shorter pulses are employed.14N MAS overtone spectroscopy is mainly limited by narrow excitation bandwidths owing to the use of very long pulses to get stronger signals. We previously reported the use of modified 90° composite pulses for broadband excitation in 1H-{NOTDQ14} D-HMQC experiments at ultra-fast MAS. In this work, we modified the 180° composite pulses, which are originally designed for spin 1/2 nuclei, for both indirect detection in 1H-{NOTDQ14} D-HMQC experiment and direct detection in one-pulse experiment, and found that the modified 180° composite pulses are useful for broadband excitation. Furthermore, we found that the bandwidth can be tailored by simply adjusting the total pulse length.Download high-res image (104KB)Download full-size image

A novel cobalt 2,3,5,6-tetrafluoroterephthalic coordination polymer has been synthesized at room temperature. With a nanosphere and lamination secondary structure, the as-prepared Co-TFBTC displayed a high capacity of 1074.6 mA h g−1 after 50 cycles in the voltage range of 0.01–3 V versus Li/Li+. The ex situ sXAS results show that Co2+ was not involved in the lithiation reaction, which suggests the redox participation of the TFBDC ligand. The present results show promise for Co-TFBDC to be applied as high performance lithium-ion battery anodes.

•A layered MOF was applied as anode for potassium-ion battery for the first time.•A reversible capacity of 188 mAh g−1 is maintained at 1 A g−1 after 600 cycles.•Both Co centers and organic ligands participate in the K-ion storage.Metal-organic frameworks (MOFs) are promising electrical storage materials due to their abundant electroactive components and large ion diffusion tunnels, however, there is no report on the employment of MOFs as electrodes for potassium-ion batteries (PIBs) hitherto. Here in this work, we firstly develop a cobalt(II) terephthalate-based layered MOF (referred as ‘L-Co2(OH)2BDC’, BDC = 1,4-benzenedicarboxylate) as an anode material for PIBs. The exceptional potassium storage performance of L-Co2(OH)2BDC is demonstrated with a high reversible capacity of 188 mAh g−1 after 600 prolonged cycles at 1 A g−1, revealing the considerable foreground of MOFs as superior potassium storage anodes. Moreover, the redox chemistry investigation of L-Co2(OH)2BDC based on X-ray absorption near edge structure (XANES) and soft X-ray spectroscopy (sXAS) techniques substantiate that both Co centers and organic ligands participate in the potassium storage, and the coordination between oxygen ions and cobalt significantly ensures the reversibility of potassiation and depotassiation processes. This work represents a significant step forward for the intensive application of MOFs in rechargeable metal batteries.Cobalt(II) terephthalate-based layered MOF anode material for potassium-ion battery with superior long-term cyclic performance is reported for the first time.Download high-res image (180KB)Download full-size image

The controllable synthesis and tailoring of the structure of metal oxide electrodes to achieve high rate capability and stability still remain formidable challenges. In this paper, a room-temperature solid–solid transformation route was introduced for the fabrication of a hierarchically structured porous CuO octahedron (HPCO) electrode by treating a copper metal–organic framework template, namely, Cu-BTC, with an alkaline solution. The HPCOs substantially inherited the morphology and size of the precursor Cu-BTC and were constructed by the assembly of many ultrathin nanosheets with average lateral sizes of ca. 250 nm. When acting as a host for the storage of Li+ ions, the as-fabricated HPCO electrode exhibited unprecedented performance that benefited from its advantageous structural features, with an ultrahigh capacity of 1201 mA h g−1 and superb high-rate performance with excellent cycling stability (1062, 615, and 423 mA h g−1 at 0.5, 2, and 5 A g−1, after 200, 400, and 400 repeated cycles, respectively). It is noteworthy that a surface redox pseudocapacitive effect contributed significantly to the high capacity and high rate of Li-ion storage of the HPCO electrode. This encouraging result may accelerate the further development of LIBs by a smart strategy for the micro/nanoengineering of metal oxide-based electrode materials.

Bimetallic coordination polymers (BiCPs) with Zn and Co were synthesized and applied as anode materials. When the rate was increased to 2 A g−1, a capacity of 622 mA h g−1 after 500 cycles could still be maintained.

We report the designed synthesis of Co 1,3,5-benzenetricarboxylate coordination polymers (CPs) via a straightforward hydrothermal method, in which three kinds of reaction solvents are selected to form CPs with various morphologies and dimensions. When tested as anode materials in Li-ion battery, the cycling stabilities of the three CoBTC CPs at a current density of 100 mA g–1 have not evident difference; however, the reversible capacities are widely divergent when the current density is increased to 2 A g–1. The optimized product CoBTC-EtOH maintains a reversible capacity of 473 mAh g–1 at a rate of 2 A g–1 after 500 galvanostatic charging/discharging cycles while retaining a nearly 100% Coulombic efficiency. The hollow microspherical morphology, accessible specific area, and the absence of coordination solvent of CoBTC-EtOH might be responsible for such difference. Furthermore, the ex situ soft X-ray absorption spectroscopy studies of CoBTC-EtOH under different states-of-charge suggest that the Co ions remain in the Co2+ state during the charging/discharging process. Therefore, Li ions are inserted to the organic moiety (including the carboxylate groups and the benzene ring) of CoBTC without the direct engagement of Co ions during electrochemical cycling.

•Graphene/carbon nanotubes sponge was fabricated via a simple freeze drying method.•The hybrid sponge was employed as anode materials of sodium ion batteries.•The hybrid sponge exhibits high capacity and superior long life cycling stability.Reduced graphene oxide/carbon nanotubes (CNTs) sponge (GCNTS) is fabricated via a simple freeze drying of graphene oxide/CNTs mixed solution and subsequent thermal treatment in nitrogen atmosphere, and used as anodes for sodium-ion batteries (SIBs) for the first time. The morphology, structure and electrochemical performance of GCNTS are characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, nitrogen adsorption-desorption isotherms, galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The results show that GCNTS with 20 wt % CNTs has a highest charge capacity of 436 mA h g−1 after 100 cycles at a current density of 50 mA g−1 and even at a high current density of 10 A g−1, a capacity of 195 mA h g−1 is maintained after 7440 cycles. The high capacity, excellent rate performance and long life cycling enable the GCNTS to be a promising candidate for practical SIBs.

Metal–organic frameworks (MOFs), are explosively developed as electrode materials for lithium-ion batteries. Mn-BTC MOF possessed low cycling stability. We therefore attempted to improve the electrochemical properties by doping cobalt into the Mn-BTC. Cobalt doped MnCo-BTC MOF greatly improved the cycling stability compared with Mn-BTC. A high capacity of 901 mA h g−1 could be obtained for MnCo-BTC at a rate of 100 mA g−1 after 150 cycles. Even at a high rate of 500 mA g−1, its capacity can still reach 445.3 mA h g−1 after 100 cycles.

We present a new and simple strategy to synthesize uniform CoxMn3−xO4 nanoparticles with a tunable composition and size. A series of Co and Mn mixed-metal coordination polymer precursors with a precise metal ratio were firstly built solvothermally by merely adjusting the molar ratio of Co and Mn. After subsequent annealing treatment, a pure CoxMn3−xO4 phase was obtained. The particle sizes of the CoxMn3−xO4 products were easily fine-tuned by varying the decomposition temperature. Particularly, the electrochemical properties of the MnCo2O4 nanomaterials for lithium-ion batteries (LIBs) were investigated as a case study. Our experimental results suggested that an optimum size guarantees maximum capacity maintenance.

•WURST-CPMGM: skip the first M echoes and only acquire the following ones.•WURST-CPMGM could eliminate the strong background signal.The WURST-CPMG pulse sequence enables: (i) observing very broad spectra due to WURST excitation, and (ii) increasing the S/N ratio due to CPMG acquisition. However, strong baseline distortions may be observed, which make the extraction of the tensor information difficult. We propose a slight modification of the sequence, WURST-CPMGM, in which we skip the first M echoes and we only acquire the following ones. This simple treatment mostly eliminates the strong background signal and the ring down effects, leading to a flat baseline.

•Composite pulses enhance robustness with respect to offset in 1H-{NOTDQ14}D-HMQC•Composite pulses lead to horn-like excitation profileWe show here that composite pulses allow broad-band excitation of nitrogen-14 overtone frequencies in proton detected D-HMQC experiments (referred to 1H-{NOTDQ14} D-HMQC). Experimental verifications have been performed on glycine, L-histidine and N-acetyl-valine (NAV) samples. Composite pulses enable symmetric excitations of 14N sites with large shift differences. Therefore, this approach is promising for recording high resolution 1H-{NOTDQ14} D-HMQC spectra of most amino-acids, pharmaceutical samples and peptides.Composite pulses allow broad-band excitation in 2D 1H-{NOTDQ14} D-HMQCFigure optionsDownload full-size imageDownload as PowerPoint slide

•Co-1,4-benzenedicarboxylate MOF is synthesized by a one-pot solvothermal method.•Reversible capacity of 1090 mA h g−1 is achieved at a current density of 200 mA g−1.•Reversible capacity of 611 mA h g−1 is achieved at a current density of 1 A g−1.•Li-ions may be inserted into the organic moieties.The reversible charging of a Co-1,4-benzenedicarboxylate MOF (Co-BDC MOF) prepared via an one-pot solvothermal method was studied for use as the anode in a Li-ion cell. It was found that this MOF anode provides high reversible capacities (1090 and 611 mA h g−1 at current densities of 0.2 and 1 A g−1, respectively), and an impressive rate performance. Such an outstanding Li-ion storage property has not been reported previously for the LIB anodes within the MOFs category. Ex-situ X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) studies of this material at different state of charge suggest that cobalt stays at Co2+ state during discharge/charge process, so that in this case Li+ may be inserted into the organic moiety without the direct participation of cobalt ions.Co-1,4-benzenedicarboxylate MOF, synthesized through a straightforward solvothermal method, shows outstanding lithium storage performance.

•Ionic conductivity of PEO6/LiAsF6 is 1.58 × 10−7 S cm−1.•Ionic conductivity of α-PEO-urea-LiAsF6 complex is 3.39 × 10−5 S cm−1.•Ionic conductivity of α-PEO-urea-LiTFSI complex is 6.03 × 10−5 S cm−1.A kind of highly-crystalline solid polymer electrolytes, based on the α-PEO-urea-LiTFSI ternary complex, is introduced here. The introduction of LiTFSI into α-PEO-urea inclusion compound has not changed the crystalline structure of the inclusion compound. Furthermore, the ionic conductivity of this α-PEO-urea-LiTFSI ternary complex has reached up to 6.03 × 10−5 S cm−1 at 303 K, where the highest conductivity of the reported highly-crystalline polymer electrolyte is only 1.58 × 10−7 S cm−1 for PEO6/LiAsF6. Our investigation might motivate further research on the different kinds of highly-crystalline polymer electrolytes based on the inclusion complexes.

Mesoporous nanostructured Co3O4 was prepared by the direct pyrolysis of a Co-based metal organic framework (MOF) template at a relatively low temperature rather than a high temperature. When tested as an anode material for lithium-ion batteries (LIBs), this porous Co3O4 exhibited a greatly enhanced performance of lithium storage. The capacity of the porous Co3O4 retained 913 mA h g−1 after 60 cycles at a current rate of 200 mA g−1. Excellent rate capability was also achieved. We also found out that the Co3O4 prepared from the MOF template at a relatively low temperature has better electrochemical performance than that prepared at high temperature.

•A noval proteoglycan, named FYGL-n, was extracted from G. lucidum.•FYGL-n was an efficient PTP1B inhibitor with IC50 7.8 ± 0.2 μg/mL.•The polysaccharide moiety of FYGL-n was composed of Ara, Gal, Rha and Glc.•The molecular weight of the FYGL-n was 72.9 kDa.•The complete sequence of FYGL-n was established indicating a hyperbranched biopolymer.Presently, an efficient protein tyrosine phosphatase 1B (PTP1B) inhibitor, named FYGL-n, was isolated from Ganoderma Lucidum and characterized for its structure and bioactivity. Structure and chain conformation of FYGL-n based on both chemical and spectroscopic analysis showed that FYGL-n was a hyperbranched heteropolysaccharide bonded with protein via both serine and threonine residues by O-type glycoside, and showed a sphere observed by AFM. Specifically, monosaccharide composition indicated that FYGL-n consisted of d-arabinose, d-galactose, l-rhamnose and d-glucose in a mole ratio of 0.08:0.21:0.24:0.47, with a molecular mass of 72.9 kDa. The analysis of amino acids in FYGL-n indicated that there were 16 common amino acids, among which aspartic acid, glycine, serine, alanine, glutamic acid and threonine were the dominant components. Also it was demonstrated that FYGL-n could inhibit the PTP1B activity on a competitive mechanism in vitro.

•Composite pulses with 8-step phase cycling (CP8P) are investigated.•CP8P approaches are feasible to excite the full wide 2H spectra.•CP8P approaches could be applied with the rf-field of 20-60kHz.Quadrupolar echo NMR spectroscopy of static solids often requires RF excitation that covers spectral widths exceeding 100 kHz, which is difficult to obtain due to instrumental limitations. In this work we revisit four well-known composite pulses (COM-I, II, III and IV) for broadband excitation in deuterium quadrupolar echo spectroscopy. These composite pulses are combined with several phase cycling schemes that were previously shown to decrease finite pulse width distortions in deuterium solid-echo experiments performed with two single pulses. The simulations and experiments show that COM-II and IV composite pulses combined with an 8-step phase cycling aid in achieving broadband excitation with limited pulse width distortions.

•The PEO polymer matrix is almost motionless.•The Li+-hopping process instead of Li+ concentration controls the conductivity.•Big crystallite sizes facilitate the Li+ transport and lead to higher conductivity.Highly crystalline polymer electrolytes exhibit remarkable ionic conductivity which is oppose to the view that crystalline phase are insulators. The crystal structures of the four PEO6/LiAsF6 (PEO refers to poly(ethylene oxide)) crystalline complexes are the same, but the ionic conductivity decreases almost 3 orders of magnitude when the molecular weight of PEO increases from 1000 Da to 6000 Da. The 2D exchange 13C NMR experiments demonstrate that the chain diffusion motion of the polymer PEO is too weak to efficiently trigger the Li+ hopping within the tunnels. Furthermore, the analysis of the conductivity spectra by the Almond–West (AW) model shows that the hopping process of Li+ ion rather than the concentration of the charge carriers controls the conductivity of the crystalline polymer electrolytes and the relaxation mechanism of Li+ ion is independent of temperature. By analyzing the peak widths of the powder X-Ray patterns, it is shown that the crystallite sizes decrease from 2800 Å to 900 Å with the increase of the molecular weight of PEO from 1000 Da to 6000 Da. On basis of the above results, we believe that the ionic conductive mechanism for highly crystalline polymer electrolytes with low molecular weight (ca. < 10 K) is different from polymer electrolytes with PEO of high molecular weight. We propose a hypothetical mechanism of the ionic conductivity in highly crystalline polymer electrolytes, that is, the polymer matrix is almost motionless while the Li+ ion hops between adjacent units. Furthermore, the bigger crystallite sizes will produce less inter-crystallite misalignments and boundaries between adjacent crystallites, which facilitate the efficient transport of Li+ ion and lead to higher conductivity.

By using a simple and efficient deuteration process, 2H has been successfully introduced into layered double hydroxides (LDHs). Due to significantly less 1H–1H homonuclear dipolar coupling, high-resolution 1H solid-state NMR spectra can now be obtained conveniently at medium to low spinning speed to extract the information of cation ordering in LDHs. Furthermore, we show that double-resonance experiments can be applied easily to investigate internuclear proximities and test possible cation-ordered superstructure models. This approach can be readily extended to LDHs with different compositions to explore the local structure and the key interactions between the cations in the layer and interlayer anions.Keywords: 2H; cation ordering; high resolution; LDH; MAS NMR;

•Low amorphous content leads to slow chain diffusion and fast orientation motion.•High amorphous content leads to fast chain diffusion and slow orientation motion.•Chain diffusion inhibits reorientation motion to facilitate chain sliding.In our previous paper, we investigated the influence of the phase structure on the polymeric chain diffusion in the complexed crystals of solid polymer electrolytes of PEO:LiAsF6 and PEO:LiCF3SO3. We observed that with the increase of the crystallinity, the chain diffusion rate decreases dramatically. In this work, by employing the 13C CODEX NMR spectroscopy, we demonstrate that opposite to the behavior of the chain diffusion motion, the local reorientation motion of polymeric chains within the complexed crystals are greatly increased with the increase of the crystallinity, which is accompanied by the change of the phase structure. The relationship between the different molecular motions within the complexed crystals and the phase structure are discussed therefore.

We explore modulation-sideband recoupling conditions of the 13C–13C Second-order Hamiltonian among Analogous nuclei plus pulse sequence (SHA+), and found that this sequence can be used in two different recoupling regimes. The first regime, νR>Δνisomax, is recommended for broad-band recoupling to avoid any rotational resonance broadening. In this regime, the spinning speed should be only slightly larger than Δνisomax, to obtain the best transfer efficiency. The second regime, νR<Δνisomax, can be used to observe long-range constraints with lower spinning speed, which increases the transfer efficiency, and may allow using bigger rotors to increase the S/N ratio.

By employing solid-state high-resolution 13C nuclear magnetic resonance (NMR), we found that the helical jump motion of crystalline poly(ethylene oxide) (PEO) segments only exists for the PEO3/LiF3SO3 complexes with the molecular weights of PEO larger than 2 × 103 g mol–1, and the helical jump rate increases with increasing the molecular weight of PEO. It is demonstrated that the helical jump rate of crystalline PEO segments depends on the relative content and chain mobility of the amorphous structures for PEO–alkali metal salt complexes. The sufficient amount of amorphous phase is the necessary condition for the helical jump motion to happen, and the chain motion in the amorphous phase might be the driving force for the helical jump motion of the crystalline PEO segments. On the basis of the above recognition, we tend to believe that the helical jump motion is corresponding to the movement of an entire PEO chain embedded in the crystallites.

Solid-state high-resolution 13C NMR studies are carried out on a series of PEO/LiCF3SO3 complexes with different EO/Li molar ratios at room temperature. The obtained spectra clearly show that there are four phases, namely the crystalline PEO, the amorphous PEO, the PEO3:LiCF3SO3 crystalline complex and the PEO3:LiCF3SO3 amorphous complex, coexisting in the samples with EO/Li molar ratios larger than 3. The solid-state 13C NMR spectrum of the PEO3:LiCF3SO3 crystalline complex exhibits six peaks with high resolution at room temperature, while the previously reported 13C NMR spectra showed only one peak. These six peaks are assigned with the combination of the 13C dipolar-INADEQUATE and the two-dimensional exchange spectra. Moreover, remarkable helical jumps of PEO segments are demonstrated to exist in the crystalline complex. Our study paves the way towards a better understanding of the phase structures and subsequently the conduction mechanism of PEO-based solid polymer electrolytes.

Ganoderma lucidum (G. lucidum) is a mushroom which has been used for health promotion for a long time in China. In the present work a neutral hetero-polysaccharide, named FYGL-1, was isolated from FYGL which was reported previously capable of antihyperglycemia in vivo for further detailed chemical structure investigation. The results of monosaccharide composition and GPC analysis indicated that FYGL-1 consisted of galactose, rhamnose and glucose in mole ratio of 1.00:1.15:3.22 with a molecular weight of 78 kDa. The detailed structure of FYGL-1 was characterized by periodate oxidation, Smith degradation, methylation analysis, along with FT-IR, GC, GC–MS, 1D 1H and 13C NMR and 2D NMR (HSQC, COSY, NOESY and TOCSY). Based on the analysis of the results, the structure of the repeating unit of FYGL-1 was established as:Figure optionsHighlights► A novel polysaccharide was extracted from Ganoderma lucidum. ► The polysaccharide was composed of Gal, Rha and Glc. ► The molecular weight of the polysaccharide was 78 kDa. ► The structure contained 1,2-β-l-Rhap, 1,3,6-α-d-Galp, 1,2,6-α-d-Glcp and 1-α-d-Glcp.

A series of Pd–PPh2–SBA-15 catalysts were synthesized by coordinating Pd(II) ions with PPh2 ligands originally bonded to SBA-15 support. The 31P CP MAS NMR spectra demonstrated that there were two kinds of coordination models coexisting in the Pd–PPh2–SBA-15 catalysts. At high P-content, the Pd nucleus preferentially coordinated with two PPh2 ligands (referred as Pd-2P model) owing to the strong chelating bond. However, at low P-content, the Pd nucleus mainly coordinated with one PPh2 ligand (denoted as Pd-1P model) due to long distance between the neighboring PPh2 ligands. The Pd–PPh2–SBA-15-con prepared by co-condensation between PdCl2[PPh2(CH2)2Si(OCH2CH3)3]2 and TEOS contained the pure Pd-2P model. The Pd-2P coordination model exhibited higher activity and better selectivity than the Pd-1P model in various C–C bond forming reactions including Suzuki, Heck, Barbier, and Sonogashira reactions, which was discussed by considering the electronic state and the coordination configuration of Pd(II) active sites, together with their stability against leaching.

The design and synthesis of nanoscale metal organic frameworks (MOFs) or coordination polymers (CPs) is of great significance in deepening their application for rechargeable batteries and supercapacitors. Here we present the designed fabrication of cobalt-nitrilotriacetic acid (CoHNta) CP nanoarchitectures via judiciously formulating reacting solvent and choosing cobalt precursor. The CoHNta with a nanorod structure (r-CoHNta) exhibits the most impressive lithium storage performance, delivering a high reversible capacity of 875 mA h g−1 at 500 mA g−1 after 300 cycles. Even at 2.4 A g−1, it still maintains a reversible capacity of ~460 mA h g−1. The performance superiority of r-CoHNta over other nanostructures is attributed to its mesoporous nanorod architecture with rapid ion transport, good flexibility, large electrode-electrolyte contact area, and robust structure stability upon prolonged cycling. More importantly, the lithiation/delithiation behavior of r-CoHNta is investigated via synchrotron-based soft X-ray spectroscopy and electron paramagnetic resonance techniques. The findings suggest that localized high-spin Co2+ in pristine r-CoHNta would gradually convert to delocalized high-spin Co2+ upon discharging, accompanying by the rehybridization of O-2p and Co-3d orbitals.Download high-res image (201KB)Download full-size image

•We developed a new class of anode materials formulated as M(OH)(OCH3).•Cobalt-based layered metal compound (Co(OH)(OCH3)) nanoplatelets are synthesized by a simple solvothermal method.•It delivers a high reversible capacity of 1150 mA h g−1 as well as excellent rate performance.Cobalt-based layered metal compound (Co(OH)(OCH3)) nanoplatelets synthesized by a facile solvothermal method were systemically characterized and investigated as an anode material for Li-ion batteries for the first time. It can deliver a high capacity of 1150 mA h g−1 at 100 mA g−1 and stay stable even after 160 cycles. It also shows high rate performance and reversibility. Its good electrochemical performance might be attributed to the unique layered structure with large layer spacing, 2D nanoplatelet-like morphology, and the void space between the nanoplatelets. The present synthesis strategy develops a potential candidate for anode materials with good performance for lithium-ion batteries.Cobalt-based layered metal compound (Co(OH)(OCH3)) nanoplatelets as a new class of anode materials with good performance and long cycle life for lithium-ion batteries.

The controllable synthesis and tailoring of the structure of metal oxide electrodes to achieve high rate capability and stability still remain formidable challenges. In this paper, a room-temperature solid–solid transformation route was introduced for the fabrication of a hierarchically structured porous CuO octahedron (HPCO) electrode by treating a copper metal–organic framework template, namely, Cu-BTC, with an alkaline solution. The HPCOs substantially inherited the morphology and size of the precursor Cu-BTC and were constructed by the assembly of many ultrathin nanosheets with average lateral sizes of ca. 250 nm. When acting as a host for the storage of Li+ ions, the as-fabricated HPCO electrode exhibited unprecedented performance that benefited from its advantageous structural features, with an ultrahigh capacity of 1201 mA h g−1 and superb high-rate performance with excellent cycling stability (1062, 615, and 423 mA h g−1 at 0.5, 2, and 5 A g−1, after 200, 400, and 400 repeated cycles, respectively). It is noteworthy that a surface redox pseudocapacitive effect contributed significantly to the high capacity and high rate of Li-ion storage of the HPCO electrode. This encouraging result may accelerate the further development of LIBs by a smart strategy for the micro/nanoengineering of metal oxide-based electrode materials.

Bimetallic coordination polymers (BiCPs) with Zn and Co were synthesized and applied as anode materials. When the rate was increased to 2 A g−1, a capacity of 622 mA h g−1 after 500 cycles could still be maintained.

Mesoporous nanostructured Co3O4 was prepared by the direct pyrolysis of a Co-based metal organic framework (MOF) template at a relatively low temperature rather than a high temperature. When tested as an anode material for lithium-ion batteries (LIBs), this porous Co3O4 exhibited a greatly enhanced performance of lithium storage. The capacity of the porous Co3O4 retained 913 mA h g−1 after 60 cycles at a current rate of 200 mA g−1. Excellent rate capability was also achieved. We also found out that the Co3O4 prepared from the MOF template at a relatively low temperature has better electrochemical performance than that prepared at high temperature.

A novel Co(II) coordination polymer, [Co(H2O)6][Co6(bpybdc)2(N3)10(H2O)4]·8H2O (bpybdc2− = 1,1′-bis(3,5-dicarboxylatophenyl)-4,4′-bipyridinium), has been synthesized from a rigid zwitterionic tetracarboxylate ligand and azide. In this compound, hexacobalt clusters with mixed μ-1,1-azide, μ3-1,1,1-azide and μ-1,3-carboxylate bridges are linked into chains by μ-1,3-azide bridges, and the chains are interlinked into 2-fold interpenetrated three-dimensional frameworks through the organic ligand and hydrogen bonds mediated by hexaaquacobalt(II) complex ions. Magnetic analysis suggested that intracluster ferromagnetic and intercluster antiferromagnetic interactions work together to give overall antiferromagnetic ground states for the azide and carboxylate bridged chain. When applied as an anode for lithium-ion batteries, the coordination polymer changes into an amorphous phase and exhibits a relatively high reversible capacity of 510 mA h g−1 with stable cycling behavior and rate performance.