Regulating cathode surface hydroxyl chemistry enables superior potassium storage.

Potassium vanadium fluorophosphate (KVPO4F) is regarded as a promising cathode candidate for potassium-ion batteries due to its high working voltage and satisfactory theoretical capacity. However, the usage of electrochemically inactive binders and redundant current collectors typically results in inferior electrochemical performance and low energy density, thus implying the important role of rational electrode structure design. Herein, we have reported a scalable and cost-effective synthesis of a cellulose-derived KVPO4F self-supporting electrode, which features a special surface hydroxyl chemistry, three-dimensional porous and conductive framework, as well as super flexible and stable architecture. The cellulose not only serves as a flexible substrate, a pore-forming agent, and a versatile binder for KVPO4F/conductive carbon but also enhances the K-ion migration ability. Benefiting from the special hydroxyl chemistry-induced storage mechanism and electrode structural stability, the flexible freestanding KVPO4F cathode exhibits high-rate performance (53.0% capacity retention with current densities increased 50-fold, from 0.2 C to 10 C) and impressive cycling stability (capacity retention up to 74.9% can be achieved over 1,000 cycles at a rate of 5 C). Such electrode design and surface engineering strategies, along with a deeper understanding of potassium storage mechanisms, provide invaluable guidance for better electrode design to boost the performance of potassium-ion energy storage systems.

Liquid-Like Li-Ion Conduction in Oxides Enabling Anomalously Stable Charge Transport across the Li/Electrolyte Interface in All-Solid-State Batteries.

The softness of sulfur sublattice and rotational PS4 tetrahedra in thiophosphates result in liquid-like ionic conduction, leading to enhanced ionic conductivities and stable electrode/thiophosphate interfacial ionic transport. However, the existence of liquid-like ionic conduction in rigid oxides remains unclear, and modifications are deemed necessary to achieve stable Li/oxide solid electrolyte interfacial charge transport. In this study, by combining the neutron diffraction survey, geometrical analysis, bond valence site energy analysis, and ab initio molecular dynamics simulation, 1D liquid-like Li-ion conduction is discovered in LiTa2 PO8 and its derivatives, wherein Li-ion migration channels are connected by four- or five-fold oxygen-coordinated interstitial sites. This conduction features a low activation energy (0.2 eV) and short mean residence time (<1 ps) of Li ions on the interstitial sites, originating from the Li-O polyhedral distortion and Li-ion correlation, which are controlled by doping strategies. The liquid-like conduction enables a high ionic conductivity (1.2 mS cm-1 at 30 °C), and a 700 h anomalously stable cycling under 0.2 mA cm-2 for Li/LiTa2 PO8 /Li cells without interfacial modifications. These findings provide principles for the future discovery and design of improved solid electrolytes that do not require modifications to the Li/solid electrolyte interface to achieve stable ionic transport.

Building K-C Anode with Ultrahigh Self-Diffusion Coefficient for Solid State Potassium Metal Batteries Operating at -20 to 120 °C.

Solid state potassium (K) metal batteries are intriguing in grid-scale energy storage, benefiting from the low cost, safety, and high energy density. However, their practical applications are impeded by poor K/solid electrolyte (SE) interfacial contact and limited capacity caused by the low K self-diffusion coefficient, dendrite growth, and intrinsically low melting point/soft features of metallic K. Herein, a fused-modeling strategy using potassiophilic carbon allotropes molted with K is demonstrated that can enhance the electrochemical performance/stability of the system via promoting K diffusion kinetics (2.37 × 10-8 cm2 s-1 ), creating a low interfacial resistance (≈1.3 Ω cm2 ), suppressing dendrite growth, and maintaining mechanical/thermal stability at 200 °C. A homogeneous/stable K stripping/plating is consequently implemented with a high current density of 2.8 mA cm-2 (at 25 °C) and a record-high areal capacity of 11.86 mAh cm-2 (at 0.2 mA cm-2 ). The enhanced K diffusion kinetics contribute to sustaining intimate interfacial contact, stabilizing the stripping/plating at high current densities. Full cells coupling ultrathin K-C composite anodes (≈50 µm) with Prussian blue cathodes and ß/ß″-Al2 O3 SEs deliver a high energy density of 389 Wh kg-1 with a retention of 94.4% after 150 cycles and fantastic performances at -20 to 120 °C.

[Construction of green infrastructure network based on spatial priority in downtown of Fuzhou, China.] / åŸºäºŽç©ºé—´ä¼˜å ˆçº§çš„ç¦å·žå¸‚ä¸­å¿ƒåŸŽåŒºç»¿è‰²åŸºç¡€è®¾æ–½ç½‘ç»œæž„å»º.

Given the facts that urban land is extremely limited and ecological environment protection is confronted with severe challenges, it is of great importance to effectively construct green infrastructure (GI) network and identify relatively important landscape ecological components. We identified and prioritized GI network centers in Fuzhou downtown area using the MSPA and the landscape connectivity evaluation. The least cost path method and gravity model were used to construct the potential corridors at multiple levels. The density analysis and blind area analysis were used to extract and prioritize the GI nodes and to obtain the optimized GI network. The results showed that the first-level GI network centers were mainly distributed in the north and south of Fuzhou downtown, while those in the central region were small and scattered. The comprehensive resistance of landscape was low in the periphery but high in the middle, with poor integral connectivity. The GI corridor system with existing corridors and potential corridors was employed to enhance the connectivity among network centers. Furthermore, the GI nodes were extracted to provide a "transfer station" for material circulation and energy flow, which could partly solve the problems including excessive substrate resistance and the long connection corridor in some areas. The spatial prioritization of GI elements could make the construction of GI network more scientific and also provide reference for the future planning period and construction timing of GI network in Fuzhou.

Nanostructured Metal-Organic Framework (MOF)-Derived Solid Electrolytes Realizing Fast Lithium Ion Transportation Kinetics in Solid-State Batteries.

Solid-state batteries are hindered from practical applications, largely due to the retardant ionic transportation kinetics in solid electrolytes (SEs) and across electrode/electrolyte interfaces. Taking advantage of nanostructured UIO/Li-IL SEs, fast lithium ion transportation is achieved in the bulk and across the electrode/electrolyte interfaces; in UIO/Li-IL SEs, Li-containing ionic liquid (Li-IL) is absorbed in Uio-66 metal-organic frameworks (MOFs). The ionic conductivity of the UIO/Li-IL (15/16) SE reaches 3.2 × 10-4 S cm-1 at 25 °C. Owing to the high surface tension of nanostructured UIO/Li-IL SEs, the contact between electrodes and the SE is excellent; consequently, the interfacial resistances of Li/SE and LiFePO4 /SE at 60 °C are about 44 and 206 Ω cm2 , respectively. Moreover, a stable solid conductive layer is formed at the Li/SE interface, making the Li plating/stripping stable. Solid-state batteries from the UIO/Li-IL SEs show high discharge capacities and excellent retentions (≈130 mA h g-1 with a retention of 100% after 100 cycles at 0.2 C; 119 mA h g-1 with a retention of 94% after 380 cycles at 1 C). This new type of nanostructured UIO/Li-IL SEs is very promising for solid-state batteries, and will open up an avenue toward safe and long lifespan energy storage systems.

Ionic Conduction in Composite Polymer Electrolytes: Case of PEO:Ga-LLZO Composites.

By dispersing Li6.25Ga0.25La3Zr2O12 (Ga-LLZO) nanoparticles in poly(ethylene oxide) (PEO) matrix, PEO:Ga-LLZO composite polymer electrolytes are synthesized. The PEO: Ga-LLZO composite with 16 vol % Ga-LLZO nanoparticles shows a conductivity of 7.2 × 10-5 S cm-1 at 30 °C, about 4 orders of magnitude higher than the conductivity of PEO. The enhancement of the ionic conductivity is closely related to the space charge region (∼3 nm) formed at the interface between the PEO matrix and the Ga-LLZO nanoparticles. The space charge region is observed by transmission electron microscope (TEM) and corroborated by the phase-field simulation. Using the random resistor model, the lithium-ion transport in the composite polymer electrolyte is simulated by the Monte Carlo simulation, demonstrating that the enhanced ionic conductivity can be ascribed to the ionic conduction in the space charge regions and the percolation of the space charge regions.

In Situ Formed Shields Enabling Li2CO3-Free Solid Electrolytes: A New Route to Uncover the Intrinsic Lithiophilicity of Garnet Electrolytes for Dendrite-Free Li-Metal Batteries.

Introduction of inorganic solid electrolytes is believed to be an ultimate strategy to dismiss dendritic Li in high-energy Li-metal batteries (LMBs), and garnet-type Li7La3Zr2O12 (LLZO) electrolytes are impressive candidates. However, the current density for stable Li plating/stripping in LLZO is still quite limited. Here, we create in situ formed Li-deficient shields by the high-temperature calcination at 900 °C. By this novel process, the formation of Li2CO3 on LLZO is restrained, and then we successfully obtain Li2CO3-free LLZO after removing the Li-deficient compounds. Without any surface modification, Li2CO3-free LLZO shows an intrinsic "lithiophilicity" characteristic. The contact angles of metallic Li on LLZO garnets are assessed by the first-principle calculation to confirm the lithiophilicity characteristic of LLZO electrolytes. The wetting of metallic Li on the Li2CO3-free LLZO surface leads to a continuous and tight Li/LLZO interface, resulting in an ultralow interfacial resistance of 49 Ω cm2 and a homogeneous current distribution in the charge/discharge processes of LMBs. Consequently, the current density for the stable Li plating/stripping in LLZO increases to 900 µA cm-2 at 60 °C, one of the highest current density for LMBs based on garnet-type LLZO electrolytes. Our findings not only offer insight into the lithiophilicity characteristics of LLZO electrolytes to suppress dendritic Li at high current densities but also expand the avenue toward high-performance, safe, and long-life energy-storage systems.

Garnet-Type Fast Li-Ion Conductors with High Ionic Conductivities for All-Solid-State Batteries.

All-solid-state Li-ion batteries with metallic Li anodes and solid electrolytes could offer superior energy density and safety over conventional Li-ion batteries. However, compared with organic liquid electrolytes, the low conductivity of solid electrolytes and large electrolyte/electrode interfacial resistance impede their practical application. Garnet-type Li-ion conducting oxides are among the most promising electrolytes for all-solid-state Li-ion batteries. In this work, the large-radius Rb is doped at the La site of cubic Li6.10Ga0.30La3Zr2O12 to enhance the Li-ion conductivity for the first time. The Li6.20Ga0.30La2.95Rb0.05Zr2O12 electrolyte exhibits a Li-ion conductivity of 1.62 mS cm-1 at room temperature, which is the highest conductivity reported until now. All-solid-state Li-ion batteries are constructed from the electrolyte, metallic Li anode, and LiFePO4 active cathode. The addition of Li(CF3SO2)2N electrolytic salt in the cathode effectively reduces the interfacial resistance, allowing for a high initial discharge capacity of 152 mAh g-1 and good cycling stability with 110 mAh g-1 retained after 20 cycles at a charge/discharge rate of 0.05 C at 60 °C.

Origin of the low grain boundary conductivity in lithium ion conducting perovskites: Li3xLa0.67-xTiO3.

Although the bulk conductivity of lithium ion conducting Li3xLa0.67-xTiO3 electrolytes reaches the level of 10-3 S cm-1, the grain boundary conductivity is orders of magnitude lower; the origin of the low grain boundary conductivity should be thoroughly understood as a prerequisite to improve the overall conductivity. Samples with grain sizes ranging from 25 nm to 3.11 µm were prepared. According to SEM and TEM investigations, the grain boundaries are free of any second phase; however, the grain boundary conductivity is still ∼4 orders of magnitude lower than the bulk conductivity. The grain boundary conductivity decreases with decreasing grain size, indicating that the low grain boundary conductivity is not dominated only by the crystallographic grain boundary. Since electrons are attracted to the grain boundaries, as reflected by the dramatically enhanced grain boundary conductivity when electrons are introduced, the grain boundary core in Li3xLa0.67-xTiO3 should be positively charged, causing the depletion of lithium ions in the adjacent space-charge layers. The very low grain boundary conductivity can be accounted for by the lithium ion depletion in the space-charge layer.

Gallium-Doped Li7La3Zr2O12 Garnet-Type Electrolytes with High Lithium-Ion Conductivity.

Owing to their high conductivity, crystalline Li7-3xGaxLa3Zr2O12 garnets are promising electrolytes for all-solid-state lithium-ion batteries. Herein, the influence of Ga doping on the phase, lithium-ion distribution, and conductivity of Li7-3xGaxLa3Zr2O12 garnets is investigated, with the determined concentration and mobility of lithium ions shedding light on the origin of the high conductivity of Li7-3xGaxLa3Zr2O12. When the Ga concentration exceeds 0.20 Ga per formula unit, the garnet-type material is found to assume a cubic structure, but lower Ga concentrations result in the coexistence of cubic and tetragonal phases. Most lithium within Li7-3xGaxLa3Zr2O12 is found to reside at the octahedral 96h site, away from the central octahedral 48g site, while the remaining lithium resides at the tetrahedral 24d site. Such kind of lithium distribution leads to high lithium-ion mobility, which is the origin of the high conductivity; the highest lithium-ion conductivity of 1.46 mS/cm at 25 °C is found to be achieved for Li7-3xGaxLa3Zr2O12 at x = 0.25. Additionally, there are two lithium-ion migration pathways in the Li7-3xGaxLa3Zr2O12 garnets: 96h-96h and 24d-96h-24d, but the lithium ions transporting through the 96h-96h pathway determine the overall conductivity.

[Expression of miR-140-5p and prediction of its target gene in human mesenchymal stem cells during adipogenic differentiation].

OBJECTIVE: To screen the differentially expressed miRNAs and their target genes in adipogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs) to better understand the mechanism for regulating the balance between osteoblast and adipocyte differentiation. METHODS: Cultured hMSCs were induced for adipogenic differentiation, and at 0, 7, 14, and 21 days of induction, the cells were examined for miRNA and mRNA expression profiles using miRNA chip and transcriptome sequencing (RNA-seq) techniques. Correlation analysis was carried out for the miRNAs and mRNAs of potential interest. The databases including TargetScan, PicTar and miRanda were used to predict the target genes of the differentially expressed miRNA. RESULTS: The expression of miR-140-5p was down-regulated and leukemia inhibitory factor receptor (LIFR) expression increased progressively during adipogenic differentiation of hMSCs, showing a negative correlation between them. Target gene prediction using the 3 databases identified LIFR as the target gene of miR-140-5p. CONCLUSION: miRNA-140-5p may play an important role by regulating its target gene LIFR during adipogenic differentiation of hMSCs.

[Safety and immunogenicity of combined hepatitis A and hepatitis B vaccine according to 0 and 6 months schedule in healthy children].

OBJECTIVE: To evaluate the safety and immunogenicity of the Bilive(TM) combined hepatitis A and hepatitis B vaccine in healthy children. METHODS: A total of 116 healthy children aged 1 - 10 years, who, without history of hepatitis A vaccine vaccination and anti-HAV negative, had completed the full immunization of hepatitis B vaccine were recruited in city of Changzhou in Jiangsu province. The Bilive(TM) combined hepatitis A and hepatitis B vaccine was administered according to a two-dose schedule (0, 6 months). The dosage was 250 U for hepatitis A antigen and 5 microg for hepatitis B surface antigen. The potential adverse effects were observed within 72 hours after vaccination. The serum samples were collected for the testing of anti-HAV and anti-HBs at month 1, 6 and 7 after initial dose. RESULTS: The local and systemic adverse reactions after immunization were slight and temporary. The rates of local and systemic adverse reactions were 12.1% (14/116) and 6.0% (7/116). The sero-conversion rates of HAV were from 92.9% (92/99) to 100.0% (101/101) and the geometric mean titers (GMT) ranged from 47.0 mIU/ml to 2762.3 mIU/ml 1, 6, 7 months after initial dose. The sero-protection rate of HBV was 86.1% (87/101) before vaccination and came up to 100.0% (101/101) one month after initial dose, and the GMTs of HBV were from 894.3 mIU/ml to 3314.3 mIU/ml 1, 6, 7 months after initial dose. CONCLUSION: The Bilive(TM) combined hepatitis A and hepatitis B vaccine has good safety and immunogenicity in healthy children who had preexisting immunity to hepatitis B virus.

[Construction and identification of cDNA library from peripheral blood lymphocytes of Tibetans in Qinghai-Tibet plateau].

AIM: To construct the full length cDNA library of the peripheral blood lymphocytes in Tibetans and to identify the quality of the library. METHODS: The lymphocytes were separated from healthy Tibetan fresh blood, and total RNA was extracted. The full length cDNA library was constructed by SMART (switching mechanism at 5' end of RNA transcript) technique. The unamplified library was titered, and the percentage of recombinant clones were determined. The library was amplified, and the size of the inserts was identified by PCR. RESULTS: The titer of the constructed cDNA library was 1.8x10(9) pfu/L with the percentage of recombinant clones above 98%, and that of the amplified library was 8x10(12) pfu/L. The insert's size ranged from 0.75 to 2.0 kb with the average length of 1.35 kb. CONCLUSION: The constructed cDNA library of peripheral blood lymphocytes of Tibetans has excellent quality, and it lays a solid founclation for further screening and cloning hypoxia-related genes of Tibetans living at high altitudes.

Synthesis and DNA binding of mu-[2,9-bis(2-imidazo[4,5-f][1,10]phenanthroline)-1,10-phenanthroline]bis[1,10-phenanthrolinecopper(II)].

A binuclear complex [(phen)Cu(mu-bipp)Cu(phen)](ClO(4))(4), where phen=1,10-phenanthroline and bipp=2,9-bis(2-imidazo[4,5-f][1,10]phenanthroline)-1,10-phenanthroline, has been synthesized and its interaction with calf-thymus DNA in the buffer containing 5mM Tris and 50mM NaCl has been studied by means of electronic absorption titration, luminescence titration and viscometric measurements. The absorbance of the complex in the range of 320-400 nm, which is mainly based on bipp showed no obvious change upon addition of DNA, while the peak at 270 nm, which is determined by both phen and bipp decreased by up to 18%. The emission band of the complex around 360 nm decreased remarkably in presence of DNA. The emission quenching of this complex by [Fe(CN)(6)](4-) was depressed greatly when bound to DNA. The relative viscosity of DNA was increased by this complex more significantly than a bipp directed intercalating reagent. These results suggest that this complex binds to calf thymus DNA by intercalation of the two phenanthrolinecopper terminals. The apparent intrinsic binding constant of the complexes with DNA was 1.6 x 10(4)M(-1) as determined by UV-visible titration.