Li_(4+x)M_xSi_(1-x)O_4(M=Fe,Cr)离子导电材料的制备与电导性能研究

采用溶胶凝胶法制备了Li4+xMxSi1-xO4(M=Fe,Cr)离子导体材料,并对样品的结构及其电导率用TG-DTA、XRD和交流阻抗仪进行了观察和测试。结果表明,采用该方法可大大降低材料的合成温度,且M(M=Fe,Cr)的掺入有利于提高材料的离子电导性。

Synthesis and Conductivity of Oxyapatite Ionic Conductor La10-xVx（SiO4）6O3＋x

Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.

The control and optimization of macro/micro-structure of ion conductive membranes for energy conversion and storage

Ion conductive membranes(ICMs)are frequently used as separators for energy conversion and storage technologies of fuel cells,flow battery,and hydrogen pump,because of their good ion-selective conduction and low electronic conductivity.Firstly,this feature article reviews the recent studies on the development of new nonfluorinated ICMs with low cost and their macro/micro-structure control.In general,these new nonfluorinated ICMs have lower conductivity than commercial perfluorinated ones,due to their poor ion transport channels.Increasing ion exchange capacity(IEC)would create more continuous hydrophilic channels,thus enhancing the conductivity.However,high IEC also expands the overall hydrophilic domains,weakens the interaction between polymer chains,enhances the mobility of polymer chains,and eventually induces larger swelling.The micro-scale expansion and macro-scale swelling of the ICMs with high IEC could be controlled by limiting the mobility of polymer chains.Based on this strategy,some ef ficient techniques have been developed,including covalent crosslinking,semi-interpenatrating polymer network,and blending.Secondly,this review introduces the optimization of macro/microstructure of both perfluorinated and nonfluorinated ICMs to improve the performance.Macro-scale multilayer composite is an ef ficient way to enhance the mechanical strength and the dimensional stability of the ICMs,and could also decrease the content of per fluorosulfonic acid resin in the membrane,thereby reducing the cost of the perfluorinated ICMs.Long side chain,multiple functionalization,small molecule inducing micro-phase separation,electrospun nano fiber,and organic–inorganic hybrid could construct more ef ficient ion transport channels,improving the ion conductivity of ICMs.

Transparent,stretchable and anti-freezing hybrid double-network organohydrogels

Stretchable ionic conductors with high transparency and excellent resilience are highly desired for flexible electronics,but traditional ionic conductive hydrogels are easy to dry and freeze.Herein,a newly hybrid crosslinking strategy is presented for preparing a stretchable and transparent hydrogel by using sodium alginate(SA)and acrylamide based on the unique physically and covalently hybrid crosslinking mechanism,which is transformed into organohydrogel by simple solvent replacement.Due to the combination of hybrid crosslinking double network and hydrogen bond interactions introduced by the glycerin-water binary solvent,the SA-poly(acrylamide)-organohydrogel(SPOH)demonstrates excellent anti-freezing(-20℃)property,stability(>2 days),transparency,stretchability(~1600%)and high ionic conductivity(17.1 mS cm^(-1)).Thus,a triboelectric nanogenerator made from SPOH(O-TENG)shows an instantaneous peak power density of 262 mW m^(-2)at a load resistance of 10 MΩand efficiently harvests biomechanical energy to drive an electronic watch and light-emitting diode.Moreover,The O-TENG exhibits favorable long-term stability(2 weeks)and temperature tolerance(-20℃).In addition,the raw materials can be prepared into SPOH fibers by a simple tubular mold method,exhibiting high transparency,which can be used for laser transmission.The various abilities of the SPOH promise the application of energy harvesting and laser transmission for wearable electronics and biomedical field.

Stable interphase chemistry of textured Zn anode for rechargeable aqueous batteries

Despite the advances of aqueous zinc(Zn)batteries as sustainable energy storage systems,their practical application remains challenging due to the issues of spontaneous corrosion and dendritic deposits at the Zn metal anode.In this work,conformal growth of zinc hydroxide sulfate(ZHS)with dominating(001)facet was realized on(002)plane-dominated Zn metal foil fabricated through a facile thermal annealing process.The ZHS possessed high Zn^(2+)conductivity(16.9 mS cm^(-1))and low electronic conductivity(1.28×10^(4)Ωcm),and acted as a heterogeneous and robust solid electrolyte interface(SEI)layer on metallic Zn electrode,which regulated the electrochemical Zn plating behavior and suppressed side reactions simultaneously.Moreover,low self-diffusion barrier along the(002)plane promoted the 2D diffusion and horizontal electrochemical plating of metallic Zn for(002)-textured Zn electrode.Consequently,the as-achieved Zn electrode exhibited remarkable cycling stability over 7000 cycles at 2 mA cm^(-2)and 0.5 mAh cm^(-2)with a low overpotential of 25 mV in symmetric cells.Pairing with a MnO_(2)cathode,the as-achieved Zn electrode achieved stable cell cycling with 92.7%capacity retention after 1000 cycles at 10 C with a remarkable average Coulombic efficiency of 99.9%.

On-site building of a Zn^(2+)-conductive interfacial layer via short-circuit energization for stable Zn anode

Aqueous zinc ion batteries(ZIBs)show great potential in large-scale energy storage systems for their advantages of high safety,low cost,high capacity,and environmental friendliness.However,the poor performance of Zn metal anode seriously hinders the application of ZIBs.Herein,we use the zinc-ion intercalatable V_(2)O_(5)nH_(2)O(VO)as the interface modification material,for the first time,to on-site build a Zn^(2+)-conductive ZnxV_(2)O_(5)nH_(2)O(ZnVO)interfacial layer via the spontaneous short-circuit reaction between the pre-fabricated VO film and Zn metal foil.Compared with the bare Zn,the ZnVO-coated Zn anode exhibits better electrochemical performances with dendrite-free Zn deposits,lower polarization,higher coulombic efficiency over 99%after long cycles and 10 times higher cycle life,which is confirmed by constructing Zn symmetrical cell and Zn|ZnSO_(4)+Li_(2)SO_(4)|LiFePO_(4) full cell.

Screening possible solid electrolytes by calculating the conduction pathways using Bond Valence method

Inorganic solid electrolytes have distinguished advantages in terms of safety and stability, and are promising to substitute for conventional organic liquid electrolytes. However, low ionic conductivity of typical candidates is the key problem. As connective diffusion path is the prerequisite for high performance, we screen for possible solid electrolytes from the 2004 International Centre for Diffraction Data （ICDD） database by calculating conduction pathways using Bond Valence （BV） method. There are 109846 inorganic crystals in the 2004 ICDD database, and 5295 of them contain lithium. Except for those with toxic, radioactive, rare, or variable valence elements, 1380 materials are candidates for solid electrolytes. The rationality of the BV method is approved by comparing the existing solid electrolytes＇ conduction pathways we had calculated with those from ex- periments or first principle calculations. The implication for doping and substitution, two important ways to improve the conductivity, is also discussed. Among them LizCO3 is selected for a detailed comparison, and the pathway is reproduced well with that based on the density functional studies. To reveal the correlation between connectivity of pathways and conductivity, a/γ-LiAlO2 and Li2CO3 are investigated by the impedance spectrum as an example, and many experimental and theoretical studies are in process to indicate the relationship between property and structure. The BV method can calculate one material within a few minutes, providing an efficient way to lock onto targets from abundant data, and to investigate the struc- ture-property relationship systematically.

Highly conductive and robust composite anion exchange membranes by incorporating quaternized MIL-101(Cr)

With well-defined channels and tunable functionality, metal-organic frameworks （MOFs） have inspired the design of a new class of ion-conductive compounds. In contrast to the extensive studies on proton- conductive MOFs and related membranes attractive for fuel cells, rare reports focus on MOFs in preparation of anion exchange membranes. In this study, chloromethylated MIL-101 （Cr） was prepared and incor- porated into chloromethylated poly （ether ether ketone） （PEEK） as a multifunctional filler to prepare imidazolium PEEK/imidazolium MIL-101（Cr） （ImPEEK/ImMIL-101（Cr）） anion exchange membrane after synchronous quaternization. The successful synthesis and chloromethylation of MIL-101（Cr） were veri- fied by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy while the enhanced performance of composite membranes in hydroxide conductivity, mechanical strength and dimensional stability were evaluated by alternating-current impedance, electronic stretching machine and measurement of swelling ratio. Specifically, incorporating 5.0wt% ImMIL-101（Cr） afforded a 71.4% increase in hydroxide conductivity at 20℃, 100% RH. Besides, the composite membranes exhibited enhanced dimensional stability and mechanical strength due to the rigid framework of ImMIL- 101（Cr）. At room temperature and the ImM1L-101（Cr） content of 10wt%, the swelling ratio of the ImPEEK/lmMIL-101（Cr） was 70.04% lower while the tensile strength was 47.5% higher than that of the pure membrane.