ZIF-67@Cellulose nanofiber hybrid membrane with controlled porosity for use as Li-ion battery separator

Zeolitic imidazolate framework-67(ZIF-67) was synthesized on the surface of cellulose nanofibers(CNFs)in methonal to address the problems of unhomogeneous pore size and pore distribution of pure CNF membrane.A combination of Energy Dispersive X-Ray Spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS) and X-ray powder diffraction(XRD) patterns were used to determine the successful synthesis of ZIF-67@CNFs.The size of the ZIF-67 particles and pore size of the ZIF-67@CNF membrane were50-200 nm and 150-350 nm, respectively.The prepared ZIF-67@CNF membrane exhibited excellent thermal stability,lower thermal shrinkage and high surface wettability.The discharge capacity retention of the Li-ion batteries(LIBs) made with ZIF-67@CNF,glass fiber(GF),CNF and commercial polymer membranes after 100 th cycle at 0.5 C rate were 88.41%,86.22%,83.27%,and 81.03%,respectively.LIBs with ZIF-67@CNF membrane exhibited a better rate capability than these with other membranes.No damage of porous structure or peel-off of ZIF-67 was observed in the SEM images of ZIF-67@CNF membrane after100 th cycle.The improved cycling performance,rate capability,and good electrochemical stability implied that ZIF-67@CNFs membrane can be considered as a good alternative LIB separator.

Effect of surface treatment for aluminum foils on discharge properties of lithium-ion battery

Aluminum foils having thicknesses of 10-20 μm are commonly employed as current collectors for cathode electrodes in Li-ion batteries. The effects of the surface morphology of the foil on battery performance were investigated by using a foil with roughened surface by chemical etching and a plain foil with smooth surface on both sides. For high-conductivity LiCoO2 active materials with large particle size, there are no significant differences in battery performance between the two types of foils. But for low-conductivity LiFePO4 active materials with small particle size, high-rate discharge properties are significantly different. The possibility shows that optimizing both the surface morphology of the aluminum foil and particle size of active material leads to improvement of the battery performance.

Engineering two-dimensional pores in freestanding TiO_2/graphene gel film for high performance lithium ion battery

As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.

Magnesium alloys as anodes for neutral aqueous magnesium-air batteries

Magnesium(Mg)is abundant,green and low-cost element.Magnesium-air(Mg-air)battery has been used as disposable lighting power supply,emergency and reserve batteries.It is also one of the potential electrical energy storage devices for future electric vehicles(EVs)and portable electronic devices,because of its high theoretical energy density(6.8 k Wh·kg^(-1))and environmental-friendliness.However,the practical application of Mg-air batteries is limited due to the low anodic efficiency of Mg metal anode and sluggish oxygen reduction reaction of air cathode.Mg metal as an anode material is facing two main challenges:high self-corrosion rate and formation of a passivation layer Mg(OH)_(2)which reduces the active surface area.In last decades,a number of Mg alloys,including Mg-Ca,Mg-Zn,commercial Mg-Al-Zn,Mg-Al-Mn,and Mg-Al-Pb alloys,have been studied as anode materials for Mg-air batteries.This article reviews the effect of alloying elements on the battery discharge properties of Mg alloy anodes.The challenges of Mg-air batteries are also discussed,aiming to provide a depth understanding for the theoretical and practical development of high-performance Mg-air batteries.

The Correlation Between Technologies and Rating Scales in Gait Analysis

Gait is a key function of human movement which plays an important role in motion analysis. Both in the clinical field and in rehabilitation, gait analysis is useful to evaluate the parameters that are modified following the administration of a protocol of adapted physical activity （APA）. Gait parameters could be measured using traditional rating scales, such as the Short Physical Performance Battery （SPPB） and technologies as a support to provide an assessment of gait quality. The aim of this study is to increase the objectivity of gait data obtained before and after a targeted APA program for a group of elderly people by integrating the traditional SPPB rating scale with the G Walk digital system. The former is an assessment tool to evaluate the functioning of lower extremity, in terms of chair stand, walk, and standing balance; whereas the latter can objectively evaluate the parameters of the gait. The sample was composed of I 1 adults aged between 67 and 94 years. The participants were chosen on the basis of a number of tests carried out to analyze their levels of autonomy, intellectual capacities and motor functioning. It has planned a six months APA protocol： before and after it, SPPB and G-Walk were administered. The results showed that space-time characteristics generally improve after APA intervention; therefore, the use of technology is a useful support for the evaluation scales.

Advanced dual-gradient carbon nanofibers/graphite felt composite electrode for the next-generation vanadium flow battery

Vanadium flow battery(VFB)is one of the most promising energy storage technologies because of its superior safety,reliability and cycle life,but the poor electrochemical performance at high cur-rent density limits its commercial application.Herein,an advanced design of the dual-gradient carbon nanofibers/graphite felt(DG-CNFs/GF)composite electrode is firstly proposed for the next-generation VFB with high power density.Specifically,there is a macro gradient distribution of CNFs along the thickness direction of the electrode,meanwhile a micro gradient distribution of CNFs is also existed along the ra-dial direction of a single fiber,and both the macro and micro gradient structure are verified through the physicochemical characterizations.In addition,the DG-CNFs/GF with a dual-gradient structure exhibits an excellent electrocatalytic activity and a fast mass transfer characteristic.It is worth noting that the energy conversion efficiencies,cycling stability in addition to power density of VFB with DG-CNFs/GF are much better than those with commercial GF,which make the dual-gradient DG-CNFs/GF to be a promis-ing alternative.Most importantly,the accomplishment of this work will provide a promising development direction of the highly efficient electrode for the next-generation VFB with high power density.

Polymer electrolyte with composite cathode for solid-state Li–CO_2 battery

The rechargeable Li-CO2 battery has attracted much attention for energy storage because of the high energy density and efficient utilization of greenhouse gas. However, it＇s still suffered by low safety issue of liquid electrolyte. Herein, a composite cathode consisting of CNTs and polymer electrolytes was fabricated by the insitu polymerization process for the polymer electrolyte-based solid-state Li-CO2 batteries. With the good dispersion of CNTs and polymer electrolyte, the composite cathode is covered by film-like discharge products Li2CO3.Furthermore, the Li-CO2 battery shows high reversible capacity （- 11,000 mAh·g^-1）, excellent cycle stability （1000 mAb·g^-1 for 100 cycles） under low charge potential （〈 4.5 V）, and outstanding rate performances at room temperature, which are much better than those of liquid electrolyte-based battery. Therefore, the polymer electrolyte-based Li-CO2 battery prepared by this strategy can be a promising candidate to meet the demands of high safety and high-performance energy storage devices.

Remarkable Performance in Lithium Battery Copper Foil Market

2018 government work report indicates that'We should strengthen fundamental role of consumption in economic development,as well as promote consumption upgrading and develop new business models of consumer sector.We will extend preferential policies on NEV vehicle purchase tax for another three years'.

Revealing performance of 78Li_(2)S-22P_(2)S_(5) glass ceramic based solid-state batteries at different operating temperatures

78Li_(2)S-22P_(2)S_(5) are sulfide electrolytes with high lithium-ion conductivity and wide electrochemical windows in the Li_(2)S-P_(2)S_(5) system,making them attractive solid electrolytes for ASSLBs.However,the role and potential of 78Li_(2)S-22P_(2)S_(5) solid electrolytes over a wide temperature range are still not fully understood.Therefore,we constructed solid-state batteries with NCM622 as the positive electrode and 78Li_(2)S-22P_(2)S_(5) glass-ceramics as the electrolyte to investigate in depth the differences in battery performance over a wide temperature range and their intrinsic mechanisms.The in-situ impedance and relaxation time distribution (DRT) demonstrated the electrochemical stability of the electrolyte over a wide temperature range,while the in-situ stacking pressure observed a large volume change during cycling at 60℃,leading to local solid-solid contact failure and poor cycling stability.This study provides insight into the advantages and problems of 78Li_(2)S-22P_(2)S_(5) in the wide temperature range as well as a basis for the construction of ASSLBs with high energy density and long cycle life.

Electrochemical performance of aluminum niobium oxide as anode for lithium-ion batteries

AlNbO_4,as lithium-ion batteries（LIBs） anode,has a high theoretical capacity of 291.5 m Ah g^-1.Here,AlNbO_4 anode materials were synthesized through a simple solid-state method.The structure,morphology and electrochemical performances of AlNbO4 anode were systematically investigated.The results show that AlNbO4 is monoclinic with C2/m space group.The scanning electron microscopy（SEM） and transmission electron microscopy（TEM） characterizations reveal the AlNbO_4 particles with the size of 100 nm^–2 lm.As a lithium-ion batteries anode,AlNbO4 delivers a high reversible capacity and good rate capability.The discharge capacity is as high as 151.0 m Ah g^-1 after 50 charge and discharge cycles at 0.1 C corresponding to capacity retention of 90.7 %.When the current density increases to 5.0C,AlNbO4 anode displays reversible discharge capacity of 73.6 m Ah g^-1 at the50 th cycle.

A nanoporous nitrogen-doped graphene for high performance lithium sulfur batteries

A nanoporous N-doped reduced graphene oxide（p-N-rGO） was prepared through carbothermal reaction between graphene oxide and ammonium-containing oxometalates as sulfur host for Li-S batteries.The p-N-rGO sheets have abundant nanopores with diameters of 10-40 nm and the nitrogen content is 2.65 at%.When used as sulfur cathode,the obtained p-N-rGO/S composite has a high reversible capacity of 1110mAhg^-1 at 1C rate and stable cycling performance with 781.8 mAhg-1 retained after 110 cycles,much better than those of the rGO/S composite.The enhanced electrochemical performance is ascribed to the rational combination of nanopores and N-doping,which provide efficient contact and wetting with the electrolyte,accommodate volume expansion and immobilize polysulfides during cycling.