Improving electrochemical performance of hybrid electrode materials by a composite of nanocellulose, reduced oxide graphene and polyaniline.

Novel ternary composites of polyaniline (PANI), reduced graphene oxide (RGO), and cellulose nanofibers (CNFs) are prepared by a chemical method for hybrid supercapacitors. CNFs were extracted from sugarcane bagasse waste in sugar production, by physicochemical processes. The composites were investigated as electrode-active materials for hybrid supercapacitors. The obtained results revealed that the presence of RGO and CNFs in the composites led to enhanced electrochemical performances, such as capacitance, rate capability, and long-term cyclability of the composite. The optimal composite of CNFs/RGO/PANI with a weight ratio of 4/16/80 can deliver the highest specific capacitance at 566.2 F g-1 under an applied current of 1 A g-1. After 1000 cycles of repetitive charge and discharge, the optimal composite retains 85.4% of its initial capacitance, whereas the PANI electrode obtained only 36.7% under the same conditions. Moreover, the supercapacitive performance is also strongly dependent on the component of the ternary composites. Overall, the composite is a promising material for hybrid supercapacitors; and the CNF component is a renewable material and a product of waste materials.

Hydrothermally synthesized nanostructured LiMnxFe1-xPO4 (x = 0-0.3) cathode materials with enhanced properties for lithium-ion batteries.

Nanostructured cathode materials based on Mn-doped olivine LiMnxFe1-xPO4 (x = 0, 0.1, 0.2, and 0.3) were successfully synthesized via a hydrothermal route. The field-emission scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyzed results indicated that the synthesized LiMnxFe1-xPO4 (x = 0, 0.1, 0.2, and 0.3) samples possessed a sphere-like nanostructure and a relatively homogeneous size distribution in the range of 100-200 nm. Electrochemical experiments and analysis showed that the Mn doping increased the redox potential and boosted the capacity. While the undoped olivine (LiFePO4) had a capacity of 169 mAh g-1 with a slight reduction (10%) in the initial capacity after 50 cycles (150 mAh g-1), the Mn-doped olivine samples (LiMnxFe1-xPO4) demonstrated reliable cycling tests with negligible capacity loss, reaching 151, 147, and 157 mAh g-1 for x = 0.1, 0.2, and 0.3, respectively. The results from electrochemical impedance spectroscopy (EIS) accompanied by the galvanostatic intermittent titration technique (GITT) have resulted that the Mn substitution for Fe promoted the charge transfer process and hence the rapid Li transport. These findings indicate that the LiMnxFe1-xPO4 nanostructures are promising cathode materials for lithium ion battery applications.

Coupling of a conductive Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 metal-organic framework with silicon nanoparticles for use in high-capacity lithium-ion batteries.

A composite of Si nanoparticles (SiNPs) and a two-dimensional (2D) porous conductive Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 (Ni3(HITP)2) metal-organic framework (MOF), namely Si/Ni3(HITP)2, is suggested as a potential anode material for Li-ion batteries (LIBs). The Ni3(HITP)2 MOF with a carbon backbone and evenly dispersed Ni and N heteroatoms showed high potential for mitigating the volume expansion of Si and enhancing the electronic conductivity as well as Li storage ability of the Si/Ni3(HITP)2 anode. The Si/Ni3(HITP)2 electrode delivered a reversible capacity of 2657 mA h g-1 after 100 cycles of discharge-charge at a rate of 0.1C. Moreover, at a high rate of 1C, the Si/Ni3(HITP)2 electrode maintained a reversible capacity of 876 mA h g-1 even after 1000 cycles. The different rate capacities were 1655, 1129, and 721 mA h g-1 at 5C, 10C and 20C, respectively. The excellent electrochemical performance of the Si/Ni3(HITP)2 electrode in terms of improved cycle life and rate capability results from the open channels of the MOF network, which are beneficial for the movement of Li+ ions through the electrolyte to the electrode and the mitigation of stress by volume expansion of Si. We believe that the coupling of conductive Ni3(HITP)2 with Si is a potential way to make an anode for high-performance LIBs.

A self-encapsulated porous Sb-C nanocomposite anode with excellent Na-ion storage performance.

In this study, a self-encapsulated Sb-C nanocomposite as an anode material for sodium-ion batteries (SIBs) was successfully synthesised using an SbCl3-citrate complex precursor, followed by a drying and calcination process under an inert N2 atmosphere. When the molar ratio of SbCl3 to citric acid was varied from 1 : 1 to 1 : 4, the Sb-C nanocomposite with a molar ratio of 1 : 3 (Sb-C3) exhibited the highest specific surface area (265.97 m2 g-1) and pore volume (0.158 cm3 g-1). Furthermore, the Sb-C3 electrode showed a high reversible capacity of 559 mA h g-1 at a rate of C/10 and maintained a high reversible capacity of 430 mA h g-1 even after 195 cycles at a rate of 1C. The Sb-C3 electrode exhibited an excellent rate capability of 603, 445, and 357 mA h g-1 at the rates of C/20, 5C, and 10C, respectively. Furthermore, a full cell composed of an Sb-C3 anode and a Na3V2(PO4)3 cathode exhibited good specific capacity and cyclability, making the Sb-C composite a promising anode material for high-performance SIBs.

Facile Synthesis of Si@SiC Composite as an Anode Material for Lithium-Ion Batteries.

Here, we propose a simple method for direct synthesis of a Si@SiC composite derived from a SiO2@C precursor via a Mg thermal reduction method as an anode material for Li-ion batteries. Owing to the extremely high exothermic reaction between SiO2 and Mg, along with the presence of carbon, SiC can be spontaneously produced with the formation of Si. The synthesized Si@SiC was composed of well-mixed SiC and Si nanocrystallites. The SiC content of the Si@SiC was adjusted by tuning the carbon content of the precursor. Among the resultant Si@SiC materials, the Si@SiC-0.5 sample, which was produced from a precursor containing 4.37 wt % of carbon, exhibits excellent electrochemical characteristics, such as a high first discharge capacity of 1642 mAh g-1 and 53.9% capacity retention following 200 cycles at a rate of 0.1C. Even at a high rate of 10C, a high reversible capacity of 454 mAh g-1 was obtained. Surprisingly, at a fixed discharge rate of C/20, the Si@SiC-0.5 electrode delivered a high capacity of 989 mAh g-1 at a charge rate of 20C. In addition, a full cell fabricated by coupling a lithiated Si@SiC-0.5 anode and a LiCoO2 cathode exhibits excellent cyclability over 50 cycles. This outstanding electrochemical performance of Si@SiC-0.5 is attributed to the SiC phase, which acts as a buffer layer that stabilizes the nanostructure of the Si active phase and enhances the electrical conductivity of the electrode.

Composite Gel Polymer Electrolyte Based on Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) with Modified Aluminum-Doped Lithium Lanthanum Titanate (A-LLTO) for High-Performance Lithium Rechargeable Batteries.

A composite gel polymer electrolyte (CGPE) based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) polymer that includes Al-doped Li0.33La0.56TiO3 (A-LLTO) particles covered with a modified SiO2 (m-SiO2) layer was fabricated through a simple solution-casting method followed by activation in a liquid electrolyte. The obtained CGPE possessed high ionic conductivity, a large electrochemical stability window, and interfacial stability-all superior to that of the pure gel polymer electrolyte (GPE). In addition, under a highly polarized condition, the CGPE effectively suppressed the growth of Li dendrites due to the improved hardness of the GPE by the addition of inorganic A-LLTO/m-SiO2 particles. Accordingly, the Li-ion polymer and Li-O2 cells employing the CGPE exhibited remarkably improved cyclability compared to cells without CGPE. In particular, the CGPE as a protection layer for the Li metal electrode in a Li-O2 cell was effective in blocking the contamination of the Li electrode by oxygen gas or impurities diffused from the cathode side while suppressing the Li dendrites.

Conducting additive-free amorphous GeO2/C composite as a high capacity and long-term stability anode for lithium ion batteries.

In this study, a novel method has been proposed for synthesizing amorphous GeO2/C composites. The amorphous GeO2/C composite without carbon black as an electrode for Li-ion batteries exhibited a high specific capacity of 914 mA h g(-1) at the rate of C/2 and enhanced rate capability. The amorphous GeO2/C electrode exhibited excellent electrochemical stability with a 95.3% charge capacity retention after 400 charge-discharge cycles, even at a high current charge-discharge of C/2. Furthermore, a full cell employing the GeO2/C anode and the LiCoO2 cathode displayed outstanding cycling performance. The superior performance of the GeO2/C electrode enables the amorphous GeO2/C to be a potential anode material for secondary Li-ion batteries.

Two isoforms of the mRNA binding protein IGF2BP2 are generated by alternative translational initiation.

IGF2BP2 is a member of a family of mRNA binding proteins that, collectively, have been shown to bind to several different mRNAs in mammalian cells, including one of the mRNAs encoding insulin-like growth factor-2. Polymorphisms in the Igf2bp2 gene are associated with risk of developing type 2 diabetes, but detailed functional characterisation of IGF2BP2 protein is lacking. By immunoblotting with C-terminally reactive antibodies we identified a novel IGF2BP2 isoform with a molecular weight of 58 kDa in both human and rodents, that is expressed at somewhat lower levels than the full-length 65 kDa protein. We demonstrated by mutagenesis that this isoform is generated by alternative translation initiation at the internal Met69. It lacks a conserved N-terminal RNA Recognition Motif (RRM) and would be predicted to differ functionally from the canonical full length isoform. We further investigated IGF2BP2 mRNA transcripts by amplification of cDNA using 5'-RACE. We identified multiple transcription start sites of the human, mouse and rat Igf2bp2 genes in a highly conserved region only 50-90 nts upstream of the major translation start site, ruling out the existence of N-terminally extended isoforms. We conclude that structural heterogeneity of IGF2BP2 protein should be taken into account when considering cellular function.