Mesoporous TiO2 Nanofiber as Highly Efficient Sulfur Host for Advanced Lithium–Sulfur Batteries

Currently, lithium–sulfur batteries su er from several critical limitations that hinder their practical application, such as the large volumetric expansion of electrode, poor conductivity and lower sulfur utilization. In this work, TiO2 nanofibers with mesoporous structure have been synthesized by electrospinning and heat treating. As the host material of cathode for Li–S battery, the as prepared samples with novelty structure could enhance the conductivity of cathode composite, promote the utilization of sulfur, and relieve volume expansion for improving the electrochemical property. The initial discharge capacity of TiO2/S composite cathode is 703 mAh/g and the capacity remained at 652 mAh/g after 200 cycles at 0.1 C, whose the capacity retention remains is at 92.7%, demonstrating great prospect for application in high-performance Li–S batteries.

Excess PbI_(2)evolution for triple-cation based perovskite solar cells with 21.9%efficiency

The triple cation mixed perovskites(Cs FAMA)are known as one of the most efficient candidates for perovskite solar cells(PSCs).It is found that the power conversion efficiency(PCE)of triple-cation based devices would increase with the test time extending,and the maximum efficiency is normally obtained after several days aging storage.Here,the relationship between enhanced device performance,excess PbI_(2)and its evolution in triple cation perovskite films of initial days was systematically explored.The Cs FAMA-PSCs are prepared by two-step methods under two environmental conditions,including in the glove box and the ambient air(30%humidity).After 7 days testing,the maximum PCE of PSCs under two conditions dramatically increased 12.4%and 12.2%,reached 21.68%and 21.89%,respectively.At initial days,the XRD peak intensities of perovskite phase gradually decreased and those corresponding to PbI_(2)increased.Along with time-resolved photoluminescence(TRPL)and kelvin probe force microscopy(KPFM),it was found that the defects were passivated with the evolution of PbI_(2).This work reveals the excess PbI_(2)and its evolution in perovskite film,which can further supplement the understanding of PbI_(2)defect passivation.

Capacity Contribution Mechanism of rGO for SnO_(2)/rGO Composite as Anode of Lithium-ion Batteries

Compared with ordinary graphite anode,SnO_(2) possesses higher theoretical specifc capacity,rich raw materials and low price.While the severe volume expansion of SnO_(2) during lithium-ion extraction/intercalation limits its further application.To solve this problem,in this work the reduced graphene oxide(rGO)was introduced as volume bufer matrix of SnO_(2).Herein,SnO_(2)/rGO composite is obtained through one-step hydrothermal method.Three-dimensional structure of rGO could efectively hinder the polymerization of SnO_(2) nanoparticles and provide more lithium storage sites attributed to high specifc surface area and density defects.The initial discharge capacity of the composite cathode is 959 mA·h·g^(-1) and the capacity remained at 300 mA·h·g^(-1) after 1000 cycles at 1 C.It proved that the rGO added in the anode has a capacity contribution to the lithium-ion battery.It changes the capacity contribution mechanism from difusion process dominance to surface driven capacitive contribution.Due to the addition of rGO,the anode material gains stable structure and great conductivity.

雄安新区西部GB014孔第四纪地层结构与演化过程

对雄安新区西部GB014孔进行了岩石磁学、古地磁和沉积学研究,建立了第四纪地层结构,为更科学利用地下空间提供基础地质支撑.岩石磁学和系统退磁实验揭示钻孔沉积物的载磁矿物主要为磁铁矿,其次为赤铁矿.依据古地磁和区域沉积特征,建立了GB014孔的磁性地层年代框架,下-中更新统界线(M/B界线)和第四系底界(G/M界线)埋深分别为33.8、135.0 m.依据沉积物岩性、结构,以及自然伽玛曲线、粒度、色度、环境磁学参数等将GB014孔划分为5个沉积体系,自下而上依次为:沉积体系Ⅴ为粗颗粒的冲积扇相,埋深为200~146.6 m,年龄为3.90~2.81 Ma,沉积速率为4.9 cm/ka;沉积体系Ⅳ为细颗粒的泛滥平原相,埋深为146.6~108.0 m,年龄为2.81~1.88Ma,沉积速率为2.76 cm/ka;沉积体系Ⅲ为粗颗粒的辫状河道相,埋深为108.0~57.6 m,年龄为1.88~1.02 Ma,沉积速率为5.86 cm/ka;沉积体系Ⅱ为细颗粒的泛滥平原相,埋深为57.6~35.8 m,年龄为1.02~0.79 Ma,沉积速率为9.48 cm/ka;沉积体系Ⅰ为夹决口扇的泛滥平原相,埋深为35.8~0 m,年龄为0~0.79 Ma,沉积速率为4.53 cm/ka.晚上新世以来GB014孔记录了3.90~2.81和1.88~0.79 Ma两次构造活跃期,其中1.88~1.02 Ma时期可能发生物源变化.太行山山前普遍存在这两期构造活动形成的粗颗粒沉积物,而中、晚更新世的砂层则可能与海侵进入渤海湾、区域降水增多有关.

Hydrothermal synthesis and characterization of MnCo_(2)O_(4) in the low-temperature hydrothermal process:Their magnetism and electrochemical properties

MnCo_(2)O_(4) octahedral structure with edge length about 500 nm was successfully synthesized by a simple hydrothermal route.With the use of NaOH,the chemical potential and the rate of ionic motion in the precursor solution were controlled,and the particle size was limited.The magnetization measurements revealed that the products exhibited ferrimagnetic characteristics with different saturation magnetization and coercivity at different measuring temperatures.In addition,the as-prepared MnCo_(2)O_(4) as anodes for lithium-ion batteries(LIBs)exhibited a reversible capacity of 1180 mA·h/g and 1090 mA·h/g at current density of 0.1 C and 1 C,respectively.The excellent cyclic performance was confirmed because the value of reversible capacity for MnCo_(2)O_(4) was 618 mA·h/g after 50 cycles at 0.1 C.Owing to the good rate performance,MnCo_(2)O_(4) octahedral products were suggested to have a promising application as anode material for LIBs.

HsGDY on Ni Foam for Loading MoS_(2)/Ni_(3)S_(2) to Enhance the Performance on Lithium-Sulfur Batteries

Lithium-sulfur batteries are considered important devices for the power of movable equipment,but there are still some challenges that limit their applications,such as how to obtain a cathode for high sulfide adsorption and rapid conversion.Here,a new strategy is proposed to enhance the performance of lithium-sulfur batteries by growing 3-dimensional hydrogen-substituted graphdiyne(HsGDY)layers on Ni foam via Glaser cross-coupling reaction to anchor MoS_(2)/Ni_(3)S_(2),enhancing the conductivity of host material of S.The results show that the 3-dimensional HsGDY framework enables the fast adsorption of lithium polysulfides and the Ni_(3)S_(2)/MoS_(2) performs as the reaction center with a low charge transfer resistance.The charge capacity of Ni@HsGDY/MoS_(2)/Ni_(3)S_(2) cell is up to 1,234.7 mAh·g^(−1) at the first circle,and the specific capacity keeps 486 mAh·g^(−1) after 500 cycles at a current density of 2 C.The incorporation of HsGDY into the cathode promotes the adsorption and the conversion of polysulfides,paving a path to obtain lithium-sulfur batteries with high energy density.

Erratum to“HsGDY on Ni Foam for Loading MoS_(2)/Ni_(3)S_(2) to Enhance the Performance on Lithium-Sulfur Batteries”

In the Research Article“HsGDY on Ni Foam for Loading MoS_(2)/Ni_(3)S_(2) to Enhance the Performance on Lithium-Sulfur Batteries”[1],the publisher made an error.“235.0 and 232.0 eV from 235.7 and 232.0 eV”should be replaced with“235.4 and 232.3 eV from 235.7 and 232.4 eV”in the sentence,“As shown in Fig.4B,after adsorbing the Li2S6,the Mo 3d_(3/2) and Mo 3d_(5/2) XPS peaks of Mo^(4+)in MoS_(2) shift toward lower binding energies of 235.0 and 232.0 eV from 235.7 and 232.0 eV,respectively,indicating increased electron density at the metal center.”This has now been corrected in the PDF and HTML(full text).