A Macromolecule Cathode for High-Performance Li-Ion and Na-Ion Batteries

Organic macromolecules have a molecular weight (Mw) between small molecules (Mw –1) and polymers (Mw > 5000 g mol–1). In this work, we design a novel organic macromolecule, namely, 1,1′-(1,4-phenylene)-bis[N,N′-bis(2-anthraquinone)]-bis[perylene-3,4,9,10-tetracarboxydiimide] (2PTCDI-4AQ). 2PTCDI-4AQ has a definite molecule structure and a large Mw value of 1679.59 g mol–1, thus showing good insolubility against most organic liquids. Meanwhile, 2PTCDI-4AQ can deliver a 12-electron redox mechanism and a theoretical specific capacity (CT) of 189 mAh g–1. Consequently, 2PTCDI-4AQ exhibits high cathode performances in Li-ion and Na-ion half/full cells. For instance, 2PTCDI-4AQ can show the discharge capacities of 174–188 mAh g–1 with a highly stable cycling retention of 93–97% during 100 cycles. Meanwhile, 2PTCDI-4AQ can also exhibit good rate performances of 130–148 mAh g–1 at the large current of 5 A g–1. As far as we know, this is the first example of macromolecule organic electrodes reported in Li-ion and Na-ion batteries

Phosphoryl/Sulfonyl-Substituted Iridium Complexes as Blue Phosphorescent Emitters for Single-Layer Blue and White Organic Light-Emitting Diodes by Solution Process

Two new phosphoryl/sulfonyl-substituted iridium complexes, POFIrpic and SOFIrpic, have been designed and synthesized on the basis of the structural frame of sky-blue FIrpic. The introduction of phosphoryl/sulfonyl moieties into the 5′-position of phenyl ring makes the emission peak blue-shift to the 460 nm, simultaneously the compounds maintain high photoluminescence quantum yields (PLQYs) of about 50% in solution. Single-layer blue and white polymer organic light-emitting diodes by full solution-process were fabricated with the following configuration: ITO/PEDOT:PSS/PVK:OXD-7:dopants/CsF/Al. The blue device based on POFIrpic shows a maximum current efficiency of 11.1 cd A^–1, a maximum external quantum efficiency of 7.1%, which are the highest ever reported for blue PhOLEDs by full solution process. The white device with POFIrpic as blue component reveals a maximum current efficiency of 25 cd A^–1, a maximum external quantum efficiency of 15%, and a good CRI value of 82

Fluorographene with High Fluorine/Carbon Ratio: A Nanofiller for Preparing Low‑κ Polyimide Hybrid Films

Sufficient amounts of fluorographene sheets with different sheet-size and fluorine/carbon ratio were synthesized for preparing of fluorographene/polyimide hybrids in order to explore the effect of fluorographene on the dielectric properties of hybrid materials. It is found that the fluorine/carbon ratio, width of band gap, and sheet-size of fluorographene play the important roles in determining the final dielectric properties of hybrids. The fluorographene with high fluorine/carbon ratio (F/C ≈ 1) presents broaden band gap, enhanced hydrophobicity, good dispersity and thermal stability, etc. Even at a very low filling, only 1 wt %, its polyimide hybrids exhibited drastically reduced dielectric constants as low as 2.1 without sacrificing thermal stability, improved mechanical properties obviously and decreased water absorption by about 120% to 1.0 wt %. This provides a novel route for improving the dielectric properties of materials and a new thought to carry out the application of fluorographene as an advanced material

Pretreatment of Lithium Surface by Using Iodic Acid (HIO₃) To Improve Its Anode Performance in Lithium Batteries

Iodic acid (HIO₃) was exploited as the effective source to build an artificial solid-electrolyte interphase (SEI) on the surface of Li anode. On one hand, HIO₃ is a weak solid-state acid and can be easily handled to remove most ion-insulating residues like Li₂CO₃ and/or LiOH from the pristine Li surface; on the other hand, both the products of LiI and LiIO₃ resulted from the chemical reactions between Li metal and HIO₃ are reported to be the ion-conductive components. As a result, the lower voltage polarization and impedance, longer cycling lifetime and higher Coulombic efficiency have been successfully achieved in the HIO₃-treated Li–Li and Li–Cu cells. By further using the HIO₃-treated Li anode into practical Li–S batteries, the impressive results also have been obtained, with average discharge capacities of 719 mAh g^–1 for 200 cycles (0.2 C) and 506 mAh g^–1 for 500 cycles (0.5 C), which were better than the Li–S batteries using the pristine Li anode (552 and 401 mAh g^–1, respectively) under the same conditions

Extending the High-Voltage Capacity of LiCoO₂ Cathode by Direct Coating of the Composite Electrode with Li₂CO₃ via Magnetron Sputtering

Surface coating of composite electrode has recently received increasing attention and has been demonstrated to be effective in enhancing the electrochemical performance of lithium ion battery (LIB) materials. In this work, an electronic-insulating but ionic-conductive lithium carbonate (Li₂CO₃) is rationally selected as the unique coating material for commercial LiCoO₂ (LCO) cathode. Li₂CO₃ is a well-known constitute in conventional solid electrolyte interface (SEI) layer, which can electrochemically protect the electrode. The carbonate coating layer is deposited on LCO composite electrodes via a facial magnetron sputtering approach. The sputtered Li₂CO₃ layer serves as an artificial SEI layer between the active material and electrolyte and can impede the formation of the primary SEI layer, which will permanently consume Li⁺ and reduce the reversible capacity of the electrode. After a 10 min Li₂CO₃ coating, the capacity retention of the composite electrode is improved from 64.4% to 87.8% when cycled at room temperature in the potential range of 3.0–4.5 V vs Li/Li⁺ for 60 cycles. The obtained discharge capacity is extended to 161 mAh g^–1, which is 36% higher than the uncoated one (118 mAh g^–1). When further increasing the charging potential up to 4.7 V, or elevating the operation temperature to 55 °C, the Li₂CO₃-coated LCO electrodes still display remarkably improved cycling stability

High-Yield Production of Highly Fluorinated Graphene by Direct Heating Fluorination of Graphene-oxide

By employing honeycomb GO with large surface area as the starting materials and using elemental fluorine, we developed a novel, straightforward topotactic route toward highly fluorinated graphene in really large quantities at low temperature. The value of F/C molar ratio approaches to 1.02. Few-layer fluorinated graphene sheets are obtained, among which the yield of monolayered FG sheet is about 10% and the number of layers is mainly in the range of 2–5. Variations in morphology and chemical structure of fluorinated graphene were explored, and some physical properties were reported

<i>Para</i>-Conjugated Dicarboxylates with Extended Aromatic Skeletons as the Highly Advanced Organic Anodes for K‑Ion Battery

A new family of the <i>para</i>-conjugated dicarboxylates embedding in biphenyl skeletons was exploited as the highly advanced organic anodes for K-ion battery. Two members of this family, namely potassium 1,1′-biphenyl-4,4′-dicarboxylate (K₂BPDC) and potassium 4,4′-<i>E</i>-stilbenedicarboxylate (K₂SBDC), were selectively studied and their detailed redox behaviors in K-ion battery were also clearly unveiled. Both K₂BPDC and K₂SBDC could exhibit very clear and highly reversible two-electron redox mechanism in K-ion battery, as well as higher potassiation potentials (above 0.3 V vs K⁺/K) when compared to the inorganic anodes of carbon materials recently reported. Meanwhile, the satisfactory specific and rate capacities could be realized for K₂BPDC and K₂SBDC. For example, the K₂BPDC anode could realize the stable rate capacities of 165/143/135/99 mAh g^–1 under the high current densities of 100/200/500/1000 mA g^–1, respectively, after its electronic conductivity was improved by mixing a very small amount of graphene. More impressively, the average specific capacities of ∼75 mAh g^–1 could be maintained for the K₂BPDC anode for 3000 cycles under the high current density of 1 A g^–1

Immunofluorescent staining for OCN in MSCs cultured on different groups of Ti disks for 14 days.

<p>Immunofluorescent staining for OCN in MSCs cultured on different groups of Ti disks for 14 days.</p

Inhibition zone diameters for the Ca-P+MNZ and Ca-P+MNZ+SIM groups after 2 and 4 days exposure to PBS.

<p>Inhibition zone diameters for the Ca-P+MNZ and Ca-P+MNZ+SIM groups after 2 and 4 days exposure to PBS.</p

Scanning electron microscopy (SEM) observations of the Ca-P coating and drug-loaded Ca-P coating.

<p>(A, B) Ca-P coating. (C, D) Ca-P coating loaded with 10⁻⁵ M SIM. (E, F) Ca-P coating loaded with 10⁻⁴ M and 10⁻³ M SIM. (G, H) Ca-P coating loaded with 10⁻² M MNZ. (I, J) Ca-P coating loaded with 10⁻³ M MNZ and 10⁻⁴ M MNZ. (K, L) Ca-P coating loaded with 10⁻² M MNZ and 10⁻⁵ SIM together.</p