Optimization Strategies Toward Functional Sodium-Ion Batteries

Exploration of alternative energy storage systems has been more than necessary in view of the supply risks haunting lithium-ion batteries.Among various alternative electrochemical energy storage devices,sodium-ion battery outstands with advantages of cost-effectiveness and comparable energy density with lithium-ion batteries.Thanks to the similar electrochemical mechanism,the research and development of lithium-ion batteries have forged a solid foundation for sodium-ion battery explorations.Advancements in sodium-ion batteries have been witnessed in terms of superior electrochemical performance and broader application scenarios.Here,the strategies adopted to optimize the battery components(cathode,anode,electrolyte,separator,binder,current collector,etc.)and the cost,safety,and commercialization issues in sodium-ion batteries are summarized and discussed.Based on these optimization strategies,assembly of functional(flexible,stretchable,self-healable,and self-chargeable)and integrated sodium-ion batteries(−actuators,−sensors,electrochromic,etc.)have been realized.Despite these achievements,challenges including energy density,scalability,trade-off between energy density and functionality,cost,etc.are to be addressed for sodium-ion battery commercialization.This review aims at providing an overview of the up-to-date achievements in sodium-ion batteries and serves to inspire more efforts in designing upgraded sodium-ion batteries.

All-cellulose-based quasi-solid-state supercapacitor with nitrogen and boron dual-doped carbon electrodes exhibiting high energy density and excellent cyclic stability

The key to construct high-energy supercapacitors is to maximize the capacitance of electrode and the voltage of the device. Realizing this purpose by utilizing sustainable and low-cost resources is still a big challenge. Herein, N, B co-doped carbon nanosheets are obtained through the proposed dual-template assisted approach by using methyl cellulose as the precursor. Due to the synergistic effects form the high surface area with the hierarchical porous structure, N/B dual doping, and a high degree of graphitization, the resultant carbon electrode exhibits a high capacitance of 572 F g^(-1)at 0.5 A g^(-1)and retains 281 F g^(-1)at 50 A g^(-1)in an acidic electrolyte. Furthermore, the symmetric device assembled using bacterial cellulose-based gel polymer electrolyte can deliver high energy density of 43 W h kg^(-1)and excellent cyclability with 97.8% capacity retention after 20 000 cycles in “water in salt” electrolyte. This work successfully realizes the fabrication of high-performance allcellulose-based quasi-solid-state supercapacitors, which brings a cost-effective insight into jointly designing electrodes and electrolytes for supporting highly efficient energy storage.

Constructing Carbon Nanobubbles with Boron Doping as Advanced Anode for Realizing Unprecedently Ultrafast Potassium Ion Storage

Carbonaceous material with favorable K^(+)intercalation feature is considered as a compelling anode for potassium-ion batteries(PIBs).However,the inferior rate performance and cycling stability impede their large-scale application.Here,a facile template method is utilized to synthesize boron doping carbon nanobubbles(BCNBs).The incorporation of boron into the carbon structure introduces abundant defective sites and improves conductivity,facilitating both the intercalation-controlled and capacitivecontrolled capacities.Moreover,theoretical calculation proves that boron doping can effectively improve the conductivity and facilitate electrochemical reversibility in PIBs.Correspondingly,the designed BCNBs anode delivers a high specific capacity(464 mAh g^(-1)at 0.05 A g^(-1))with an extraordinary rate performance(85.7 mAh g^(-1)at 50 A g^(-1)),and retains a considerable capacity retention(95.2%relative to the 100th charge after 2000 cycles).Besides,the strategy of pre-forming stable artificial inorganic solid electrolyte interface effectively realizes high initial coulombic efficiency of 79.0%for BCNBs.Impressively,a dual-carbon potassium-ion capacitor coupling BCNBs anode displays a high energy density(177.8 Wh kg^(-1)).This work not only shows great potential for utilizing heteroatom-doping strategy to boost the potassium ion storage but also paves the way for designing high-energy/power storage devices.

Sulfur and nitrogen codoped cyanoethyl cellulose-derived carbon with superior gravimetric and volumetric capacity for potassium ion storage

We fabricated sulfur and nitrogen codoped cyanoethyl cellulose-derived carbons(SNCCs)with state-of-the-art electrochemical performance for potassium ion battery(PIB)and potassium ion capacitor(PIC)anodes.At 0.2,0.5,1,2,5,and 10 A g−1,the SNCC shows reversible capacities of 369,328,249,208,150,and 121 mA h g−1,respectively.Due to a high packing density of 1.01 g cm^(−3),the volumetric capacities are also uniquely favorable,being 373,331,251,210,151,and 122 mA h cm^(−3)at these currents,respectively.SNCC also shows promising initial Coulombic efficiency of 69.0%and extended cycling stability with 99.8%capacity retention after 1000 cycles.As proof of principle,an SNCC-based PIC is fabricated and tested,achieving 94.3Wh kg^(−1)at 237.5Wkg^(−1)and sustaining over 6000 cycles at 30 A g−1 with 84.5%retention.The internal structure of S and N codoped SNCC is based on highly dilated and defective graphene sheets arranged into nanometer-scale walls.Using a baseline S-free carbon for comparison(termed NCC),the role of S doping and the resultant dilated structure was elucidated.According to galvanostatic intermittent titration technique and electrochemical impedance spectroscopy analyses,as well as COMSOL simulations,this structure promotes rapid solid-state diffusion of potassium ions and a solid electrolyte interphase that is stable during cycling.X-ray diffraction was used to probe the ion storage mechanisms in SNCC,establishing the role of reversible potassium intercalation and the presence of KC36,KC24,and KC8 phases at low voltages.

Encapsulation of MnS Nanocrystals into N,S-Co-doped Carbon as Anode Material for Full Cell Sodium-Ion Capacitors

Sodium-ion capacitors(SICs)have received increasing interest for grid stationary energy storage application due to their affordability,high power,and energy densities.The major challenge for SICs is to overcome the kinetics imbalance between faradaic anode and nonfaradaic cathode.To boost the Na+reaction kinetics,the present work demonstrated a high-rate MnS-based anode by embedding the MnS nanocrystals into the N,S-co-doped carbon matrix(MnS@NSC).Benefiting from the fast pseudocapacitive Na+storage behavior,the resulting composite exhibits extraordinary rate capability(205.6 mAh g−1 at 10 A g−1)and outstanding cycling stability without notable degradation after 2000 cycles.A prototype SIC was demonstrated using MnS@NSC anode and N-doped porous carbon(NC)cathode;the obtained hybrid SIC device can display a high energy density of 139.8 Wh kg−1 and high power density of 11,500 W kg−1,as well as excellent cyclability with 84.5%capacitance retention after 3000 cycles.The superior electrochemical performance is contributed to downsizing of MnS and encapsulation of conductive N,S-co-doped carbon matrix,which not only promote the Na+and electrons transport,but also buffer the volume variations and maintain the structure integrity during Na+insertion/extraction,enabling its comparable fast reaction kinetics and cyclability with NC cathode.

Research on the Financial Maturity of the Yangtze River Economic Belt

The Yangtze River Economic Belt is a key development project in China,and financial development is the core driving force for economic growth in the Yangtze River Economic Belt.At present,the financial development of the Yangtze River Economic Belt is not balanced,and there is an urgent need to quantify the differences in financial development.Drawing on the research of"maturity model"at home and abroad,from the two new perspectives of subjective and objective,the financial development difference is introduced into the maturity model as an organic whole,forming financial maturity and its indicator system,then taking the Yangtze River Economic Belt as the research object,the principal component analysis method is used to calculate the maturity.The results show that the financial development of the middle and lower reaches of the Yangtze River Economic Belt has obvious gradient differences both subjectively and objectively.The financial acceptance of the lower reaches of the Yangtze River and the total financial structure and structure are significantly higher than the middle and upper reaches,while financial efficiency is lower than the middle and upper reaches due to factors such as financial costs.Therefore,the financial development of the Yangtze River Economic Belt needs to improve the systematicness of finance,coordinate the growth of financial volume and structural adjustment,and improve the overall financial operation efficiency.

MXene-based all-solid flexible electrochromic microsupercapacitor

With the increasing demand for multifunctional optoelectronic devices,flexible electrochromic energy storage devices are being widely recognized as promising platforms for diverse applications.However,simultaneously achieving high capacitance,fast color switching and large optical modulation range is very challenging.In this study,the MXenebased flexible in-plane microsupercapacitor was fabricated via a mask-assisted spray coating approach.By adding electrochromic ethyl viologen dibromide(EVB)into the electrolyte,the device showed a reversible color change during the charge/discharge process.Due to the high electronic conductivity of the MXene flakes and the fast response kinetics of EVB,the device exhibited a fast coloration/bleaching time of 2.6 s/2.5 s,a large optical contrast of 60%,and exceptional coloration efficiency.In addition,EVB acted as a redox additive to reinforce the energy storage performance;as a result,the working voltage window of the Ti_(3)C_(2)-based symmetric aqueous microsupercapacitor was extended to 1 V.Moreover,the device had a high areal capacitance of 12.5 mF cm^(−2)with superior flexibility and mechanical stability and showed almost 100%capacitance retention after 100 bending cycles.The as-prepared device has significant potential for a wide range of applications in flexible and wearable electronics,particularly in the fields of camouflage,anticounterfeiting,and displays.

Flexible electrochromic fiber with rapid color switching and high optical modulation

Though flexible electrochromic devices have shown huge potential application in the fields of safety warning,display and smart windows,limited attention was paid on preparing flexible electrochromic fiber because of the difficulty in fabricating the multilayer electrochromic device structure in one-dimensional form.In this study,a flexible electrochromic nylon fiber based on Ag nanowires(NWs)/PEDOT:PSS/WO3 nanoparticles(NPs)(PEDOT:PSS=poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid)is successfully fabricated,delivering rapid color switching(2.5 and 9 s for bleaching and coloration)and high optical modulation(65.5%at 633 nm),and sustainable to repeated mechanical deformations.Ag NWs,PEDOT:PSS and WO3 NPs were dip-coated on the nylon fiber,resulting in an electrochromic fiber electrode with stable fiber resistance of 50-100Ω/10 cm,which can withstand mechanical deformation against 300 times of bending cycles with bending radius of 0.5 cm,and sustain 30 times of tape-peeling.During the galvanostatic tests,the capacitance of the electrochromic electrode can maintain 70%of the initial value even after 5,000 times of charge-discharge cycles.Even in knotted shape,the fiber still shows excellent color contrast.This study provides a novel method to construct flexible electrochromic fiber and pave the way for the development of flexible optoelectronic devices,such as flexible and wearable displays.

Organic Passivation of Deep Defects in Cu(In,Ga)Se_(2) Film for Geometry-Simplified Compound Solar Cells

Diverse defects in copper indium gallium diselenide solar cells cause nonradiative recombination losses and impair device performance.Here,an organic passivation scheme for surface and grain boundary defects is reported,which employs an organic passivation agent to infiltrate the copper indium gallium diselenide thin films.A transparent conductive passivating(TCP)film is then developed by incorporating metal nanowires into the organic polymer and used in solar cells.The TCP films have a transmittance of more than 90%in the visible and nearinfrared spectra and a sheet resistance of~10.5Ω/sq.This leads to improvements in the open-circuit voltage and the efficiency of the organic passivated solar cells compared with control cells and paves the way for novel approaches to copper indium gallium diselenide defect passivation and possibly other compound solar cells.

Digitally programmable organic light‐emitting tetrodes

Limited to the structure of traditional light‐emitting devices,electronic devices that can directly convert machine language into human visual information without introducing any back‐end circuit are still not easy to achieve.Based on a specially designed three‐phase co‐planar electrode structure,a new type of three‐phase alternating current driven organic light‐emitting device with the integration of emission and control functions,full‐color tunability and simple device structure is demonstrated in this study.We integrate the light‐emitting function of color‐tunable light‐emitting devices and the switching of three triodes in a single three phase organic light‐emitting device.The state control of luminous color and luminance intensity merely requires the introduction of a kind of machine language,that is an easy‐to‐program 6‐bit binary number coded digital signals.The color adjustable area covers 66%of the color triangle of the National Television System Committee.Such simple and easy‐to‐integrate light‐emitting system has great potential applications in the next‐generation man‐machine interface.

零误差计算

研究采用有误差的数值计算来获得无误差的准确值具有重要的理论价值和应用价值.这种通过近似的数值方法获得准确结果的计算被称为零误差计算.本文首先指出,只有一致离散集合中的数才能够开展零误差计算,即有非零隔离界的数集,这也是"数"可以进行零误差计算的一个充要条件.以此为基本出发点,本文分析代数数零误差计算的最低理论精度,该精度对应于恢复近似代数数的准确值时必要的误差控制条件,但由于所采用恢复算法的局限性,这一理论精度往往不能保证成功恢复出代数数的准确值.为此,本文给出采用PSLQ (partial-sum-LQ-decomposition)算法进行代数数零误差计算所需的精度控制条件,与基于LLL (Lenstra-Lenstra-Lovász)算法相比,该精度控制条件关于代数数次数的依赖程度由二次降为拟线性,从而可降低相应算法的复杂度.最后探讨零误差计算未来的发展趋势.

Plasma enhanced chemical vapor deposition of excellent a-Si：H passivation layers for a-Si：H/c-Si heterojunction solar cells at high pressure and high power

The intrinsic a-Si：H passivation layer inserted between the doped a-Si：H layer and the c-Si substrate is very crucial for improving the performance of the a-Si：H/c- Si heterojunction （SHJ） solar cell. The passivation performance of the a-Si：H layer is strongly dependent on its microstructure. Usually, the compact a-Si：H deposited near the transition from the amorphous phase to the nanocrystalline phase by plasma enhanced chemical vapor deposition （PECVD） can provide excellent passivation. However, at the low deposition pressure and low deposition power, such an a-Si：H layer can be only prepared in a narrow region. The deposition condition must be controlled very carefully. In this paper, intrinsic a- Si：H layers were prepared on n-type Cz c-Si substrates by 27.12 MHz PECVD at a high deposition pressure and high deposition power. The corresponding passivation perfor- mance on c-Si was investigated by minority carrier lifetime measurement. It was found that an excellent a-Si：H passivation layer could be obtained in a very wide deposition pressure and power region. Such wide process window would be very beneficial for improving the uniformity and the yield for the solar cell fabrication. The a-Si：H layer microstructure was further investigated by Raman and Fourier transform infrared （FTIR） spectro-scopy characterization. The correlation between the microstructure and the passivation performance was revealed. According to the above findings, the a-Si：H passivation performance was optimized more elaborately. Finally, a large-area SHJ solar cell with an efficiency of 22.25% was fabricated on the commercial 156 mm pseudo-square n-type Cz c-Si substrate with the opencircuit voltage （Voc） of up to 0.732 V.

Fast and high-fidelity generation of photonic Greenberger-Horne-Zeilinger states in circuit QED

A fast scheme to generate Greenberger-Horne-Zeilinger states between different cavities in circuit QED systems is proposed.To implement this scheme,we design a feasible experimental device with three qubits and three cavities.In this device,all the couplings between qubit and qubit,cavity and qubit are tunable and are independent with frequencies,and thus the shortcut to adiabaticity technique can be directly applied in our scheme.It is demonstrated that the GHZ state can be generated rapidly with high fidelity in our scheme.

Highly expressed SERCA2 triggers tumor cell autophagy and is a druggable vulnerability in triple-negative breast cancer

Chemoresistance remains a major obstacle to successful treatment of triple negative breast cancer(TNBC).Identification of druggable vulnerabilities is an important aim for TNBC therapy.Here,we report that SERCA2 expression correlates with TNBC progression in human patients,which promotes TNBC cell proliferation,migration and chemoresistance.Mechanistically,SERCA2 interacts with LC3B via LIR motif,facilitating WIPI2-independent autophagosome formation to induce autophagy.Autophagy-mediated SERCA2 degradation induces SERCA2 transactivation through a Ca^(2+)/CaMKK/CREB-1 feedback.Moreover,we found that SERCA2-targeting small molecule RL71 enhances SERCA2-LC3B interaction and induces excessive autophagic cell death.The increase in SERCA2 expression predisposes TNBC cells to RL71-induced autophagic cell death in vitro and in vivo.This study elucidates a mechanism by which TNBC cells maintain their high autophagy activity to induce chemoresistance,and suggests increased SERCA2 expression as a druggable vulnerability for TNBC.

Heat transfer characteristics in a rotating AR=4:1 channel with different channel orientations at high rotation numbers

In order to reveal the effect of channel orientations on rotational heat transfer performance,this paper presents an experimental model of AR=4:1 smooth rectangular channel.The stationary and rotational heat transfer characteristics of the channel are studied in the range of Re=10,000-40,000 and Ro=0-1.23 under the channel orientation of 90°and 135°,which represent the basic one and realistic one,respectively.The experimental results indicate that for the trailing wall,the 90°channel shows a typical large range enhancement of rotational heat transfer,while the rotational effect becomes negative in most areas at 135°case.As the rotation number exceeds 0.7,the heat transfer of the trailing surface is greatly improved by rotational effect in 90°channel.When the channel was orientated at 135°,the leading surface heat transfer is more sensitive to rotation under the low rotation number(Ro<0.3),and 20%-30%worse than non-rotating cases.The averaged Nusselt ratios correlations under the channel orientation of 90°and 135°have been developed for further engineering applications.