LiPO_(2)F_(2) electrolyte additive for high-performance Li-rich cathode material

Li-rich layered oxide cathodes have received considerable attention because of the high operating potential and specific capacity. However, the structural instability and parasitic reactions at high potential cause severe degradation of the electrochemical performance. In our studies, the cycling stability of Li_(1.14)Ni_(0.133)Co_(0.133)Mn_(0.544)O_(2) cathode is improved with LiPO_(2)F_(2) electrolyte additive. After 500 cycles, the capacity retention is increased from 53.6% to 85% at 3 C by LiPO_(2)F_(2) modification. This performance is mainly attributed to the enhanced interfacial stability of the Li-rich cathode. Based on systematic characterization, LiPO_(2)F_(2) additive was found to promote a stable interface film on the cathode surface during the cycling and mitigates the interfacial side reactions. This study provides new insights for improving high-potential Li-rich layered oxide batteries.

钙钛矿同质结太阳电池研究进展

钙钛矿太阳电池制备工艺简单,效率提升迅速,被认为是最具应用潜力的新一代光伏技术之一。近年来,大量研究表明,钙钛矿光电材料可以通过自掺杂或外源掺杂的方式实现薄膜导电类型(p型或n型)的定向调控;而具有双层薄膜结构的钙钛矿p-n同质结可以通过薄膜双沉积技术制备,这为钙钛矿同质结太阳电池的设计与制备提供了技术基础。新型钙钛矿同质结太阳电池摒弃传统的电子传输层和空穴传输层,可简化电池结构,不仅有利于提升电池工作稳定性,降低成本,更能进一步释放钙钛矿太阳电池在柔性和半透明应用中的潜力,推动钙钛矿电池的实用化进程。本文围绕钙钛矿同质结太阳电池,综述了钙钛矿光电材料p/n特性掺杂和钙钛矿同质结的研究进展,讨论了钙钛矿同质结太阳电池的基本结构和工作原理,并对其当前存在的技术问题和应用前景进行了总结与展望。

Computational Study of Ternary Devices: Stable, Low-Cost,and Efficient Planar Perovskite Solar Cells

Although perovskite solar cells with power conversion efficiencies(PCEs) more than 22% have been realized with expensive organic charge-transporting materials, their stability and high cost remain to be addressed. In this work, the perovskite configuration of MAPbX(MA = CH_3 NH_3,X = I_3, Br_3, or I_2Br) integrated with stable and low-cost Cu:Ni Oxhole-transporting material, ZnO electron-transporting material, and Al counter electrode was modeled as a planar PSC and studied theoretically. A solar cell simulation program(wx AMPS), which served as an update of the popular solar cell simulation tool(AMPS: Analysis of Microelectronic and Photonic Structures), was used. The study yielded a detailed understanding of the role of each component in the solar celland its effect on the photovoltaic parameters as a whole. The bandgap of active materials and operating temperature of the modeled solar cell were shown to influence the solar cell performance in a significant way. Further, the simulation results reveal a strong dependence of photovoltaic parameters on the thickness and defect density of the light-absorbing layers. Under moderate simulation conditions, the MAPb Br_3 and MAPbI _2 Br cells recorded the highest PCEs of 20.58 and 19.08%, respectively, while MAPbI_3 cell gave a value of 16.14%.

Force Spectrum of Single CsgA Nanofiber Reveal Surprising Properties

CsgA protein monomers consist of aβ-helix of five repeat units possessing several conservative residues and thus,inherently fibrillate.CsgA protein monomers could self-assemble into hierarchical nanofiber structure cross multiple scales after expression and secretion by E.Coli cells.Previous researches show that CsgA nanofibers could provide adhesion,stiffness,and mechanical homogeneity for the biofilms,host cells’fibronectin binding for internalization,or protection against phage attack.CsgA nanofibers have obtained various applications in material science and synthetic biology.To illustrate,CsgA nanofibers have characteristics of intrinsic hierarchical structures across multiple scales,robustness in harsh environments and programmable functionality via biological tools.Studying the force spectrum or mechanical properties of the nanofiber can provide fundamental information of self-assembly process and ultra-stability in extreme conditions.Single molecule techniques such as atomic force microscopy,optical tweezers,and magnetic tweezers have been widely applied to study proteins.In these studies,proteins are usually chemically conjugated or genetically constructed to have a tag such as histidine,cysteine or biotin.Genetic engineering requires modification of the plasmids encoding the specific protein,and also involve special protein expression and purification.Such study needs collaboration from multi-disciplinary.It normally studies one protein at a time which gives out clear signal but lacks throughput and efficiency.Here we have established a simple method to measure all kinds of proteins without labels.The carboxyl terminus of a protein is attached to the amine group on a magnetic bead,and the amine terminus of the protein is attached to glutaraldehyde on the glass slide.Then we used magnetic tweezers to manipulate and stretched the bead and protein.Extension versus rotation relation was used to identify a single protein or protein fibril.The fiber under tension is also observed by Scanning Electronic Microcopy which convinces that single CsgA-His fibril is linked to a microbead.The peak of diameter distribution is around 15 nm.The fracture of fibers was observed in real time on SEM.Force-extension curves of single fibers are obtained in real time.The force-extension curves generally agree with the worm like chain model.The persistence lengths from the fitting are from 0.9 to 49.8 nm.The elongation ratio increases gradually with force until reaches a plateau.The maximum elongation ratio of 78 nanofibers were made into an elongation ratio distribution diagram,more than half of CsgA-His nanofibers has an elongation ratio from 0 to 2,some are distributed in 2~10,and a few are distributed in 10~18.The maximum elongation ratio of CsgA-His nanofibers is 17.1,indicating that the fibril’s flexibility is much higher than DNA or silk fiber.For forces less than 20 pN,the extension was reversible.With a 42.1 pN holding force,the extension jumped in steps of from 30 to 365 nm and was irreversible.At the scale tested,the jumps corresponded to the unfolding of multiple beta sheets in the fiber.Work for CsgA-His nanofibers during stretching increase with the normalized strain fractions.The experimental data agree with a theoretical prediction for a single CsgA protein from a SMD calculation.Therefore,our results provide key information for the understandings of CsgA protein nanofiber assembly and biofilm robustness.

Solid electrolyte interphase on anodes in rechargeable lithium batteries

Highly safe and efficient rechargeable lithium batteries have become an indispensable component of the intelligent society powering smart electronics and electric vehicles.This review summarizes the formation principle,chemical compositions,and theoretical models of the solid electrolyte interphase(SEI)on the anode in the lithium battery,involving the functions and influences of the electroactive materials.The discrepancies of the SEI on different kinds of anode materials,as well as the choice and design of the electrolytes are detailedly clarified.Furthermore,the design strategies to obtain a stable and efficient SEI are outlined and discussed.Last but not least,the challenges and perspectives of artificial SEI technology are briefly proposed for the development of high-efficiency batteries in practice.

Excellent light-capture capability of trilobal SiNW for ultra-high JSC in single-nanowire solar cells

Single-.nanowire solar cells with a unique light-concentration property are expected to exceed the Shockley-Queisser limit.The architecture of single nanowire is an important factor to regulate its optical performance.We designed a trilobal silicon nanowire(SiNW)with two cquivalent scales that possesses superior light-absorption efficiency in the whole wavelength range and shows good tolerance for incident angle.The electric field distribution in this geometry is concentrated in the blade with small equivalent scale and pivot with large equivalent scale,respectively,in the short wavelength range and long wavelength range.Corresponding good light absorption of trilobal SiNW in the two wavelength ranges leads to stronger total light absorption capacity than that of cylindrical SiNW.Trilobal single nanowire solar cells can obtain a short-circuit current density(JSC)of 647 mA·cm^2,which provides a new choice for designing single nanowire with excellent light-capture capability.

Research progress in improving the performance of PEDOT:PSS/Microand Nano-textured Si heterojunction for hybrid solar cells

Silicon-based hybrid solar cells(HSCs),especially PEDOT:PSS/Si HSC,have attracted the interest of researchers because they combine the advantages of organic and inorganic materials.A high quality PEDOT:PSS/Si heterojunction is the key to the good performance of PEDOT:PSS/Si HSC.However,as generally requisite to enhance light absorption for HSCs,Si Micro/Nano structures will reduce the interface contact quality between PEDOT:PSS and Si surface.The inferior interface contact quality will limit the separation efficiency of the photogenerated carriers.In this paper,we summarize the research progress in improving the interface contact between Si Micro/Nano structures and PEDOT:PSS film from three aspects:the optimization of Si Micro/Nano structures aimed to improve the fluid properties of PEDOT:PSS solution,the material modification of PEDOT:PSS and interface modification with the purpose to enlarge the heterojunction area and improve the electrical contact,and the specific deposition process of PEDOT:PSS solution developed to achieve the high filling rate of PEDOT:PSS on Si Micro/Nano structures.The insight of this paper is helpful for the preparation of high-quality heterojunction,which is vitally important for the development of high efficiency PEDOT:PSS/Si HSCs.