3D Hierarchical Co–Al Layered Double Hydroxides with Long-Term Stabilities and High Rate Performances in Supercapacitors

Three-dimensional(3D) flower-like Co–Al layered double hydroxide(Co–Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water and butyl alcohol. Owing to the unique hierarchical structure and modification by butyl alcohol, the electrochemical stability and the charge/mass transport of the Co–Al-LDHs was improved. When used in supercapacitors, the obtained Co–Al-LDHs deliver a high specific capacitance of 838 Fg^(-1) at a current density of 1 Ag^(-1)and excellent rate performance(753 Fg^(-1) at 30 Ag^(-1) and 677 Fg^(-1) at 100 Ag^(-1)), as well as excellent cycling stability with 95% retention of the initial capacitance even after 20,000 cycles at a current density of 5 Ag^(-1). This work provides a promising alternative strategy to enhance the electrochemical properties of supercapacitors.

Revisiting the capacity-fading mechanism of P2-type sodium layered oxide cathode materials during high-voltage cycling

P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.

追踪锂金属负极的压力与形貌变化

采用高载量氧化物正极(>4mAh·cm^(-2))和超薄锂金属负极(<50μm)可以构建高比能锂金属二次电池。然而,该类电池的循环寿命和安全性受到锂金属不可控沉积的严重制约。高比表面积的锂枝晶和锂“苔藓”导致了较低的库伦效率,前者有一定可能穿刺隔膜,造成电池内短路,是亟待解决的安全隐患。因此,提升锂金属二次电池的循环寿命和安全性的关键在于实现锂金属的致密沉积。文献中已有多种化学方法可达到这样的效果。由于锂金属较软,受力容易发生形变,对锂金属电池施加机械压力是另一种促进锂金属致密沉积和提高循环性能的方法。然而,机械压力、锂金属形态的演变、和循环性能之间的关系尚未被完全理解。本文报道了一种基于薄膜压力传感器的电池压力测量装置,可以实时跟踪纽扣型锂金属电池内部的压力变化,并且探究外加机械压力对电池循环性能的影响。研究发现,在纽扣电池和高比能的软包电池(5 Ah,>380 Wh·kg^(-1))中,一定程度的压力可以促进锂金属的致密沉积,改善电池循环性能;而过大的压力则会导致锂金属向负极内部沉积,造成负极变形和电池性能恶化。我们的研究结果凸显了压力控制对于锂金属沉积行为的重要作用,为进一步改善高比能锂金属电池的循环性能提供了指导。

High Fe^(LS)(C)electrochemical activity of an iron hexacyanoferrate cathode boosts superior sodium ion storage

Sodium iron hexacyanoferrate(FeHCF)is one of the most promising cathode materials for sodium-ion batteries(SIBs)due to its low cost theoretical capacity.However,the low electrochemical activity of Fe^(LS)(C)in FeHCF drags down its practical capacity and potential plateau.Herein,FeHCF with high Fe^(LS)(C)electrochemical activity(C-FeHCF)is synthesized via a facile citric acid-assisted solvothermal method.As the cathode of SIBs,C-FeHCF shows superior cycling stability(ca.87.3%capacity retention for 1000 cycles at 10 C)and outstanding rate performance(ca.68.5%capacity retention at 50 C).Importantly,the contribution of Fe^(LS)(C)to the whole capacity was quantitatively analyzed via combining dQ/dV and discharge curve for the first time,and the index reaches 44.53%for C-FeHCF,close to the theoretical value.In-situ X-ray diffraction proves the structure stability of C-FeHCF during charge-discharge process,ensuring its superior cycling performance.Furthermore,the application feasibility of the C-FeHCF cathode in quasi-solid SIBs is also evaluated.The quasi-solid SIBs with the C-FeHCF cathode exhibit excellent electrochemical performance,delivering an initial discharge capacity of 106.5 mAh g^(−1) at 5 C and high capacity retention of 89.8%over 1200 cycles.This work opens new insights into the design and development of advanced cathode materials for SIBs and the beyond.

Process engineering in electrochemical energy devices innovation

This review focuses on the application of process engineering in electrochemical energy conversion and storage devices innovation. For polymer electrolyte based devices, it highlights that a strategic simple switch from proton exchange membranes(PEMs) to hydroxide exchange membranes(HEMs) may lead to a new-generation of affordable electrochemical energy devices including fuel cells, electrolyzers, and solar hydrogen generators. For lithium-ion batteries, a series of advancements in design and chemistry are required for electric vehicle and energy storage applications. Manufacturing process development and optimization of the LiF eP O_4/C cathode materials and several emerging novel anode materials are also discussed using the authors' work as examples.Design and manufacturing process of lithium-ion battery electrodes are introduced in detail, and modeling and optimization of large-scale lithium-ion batteries are also presented. Electrochemical energy materials and device innovations can be further prompted by better understanding of the fundamental transport phenomena involved in unit operations.

Engineering optimization approach of nonaqueous electrolyte for sodium ion battery with long cycle life and safety

Electrolyte design strategies are closely related to the capacities, cycle life and safety of sodium–ion batteries. In this study, we aimed to optimize electrolyte with the focus on engineering aspects. The basic physicochemical properties including ionic conductivity, viscosity,wettability and thermochemical stability of the electrolytes using Na PF6 as the solute and the mixed solvent with different components of EMC,DMC or DEC in PC or EC were systematically measured. Ah pouch cell with NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)/hard carbon electrodes was used to evaluate the performance of the prepared electrolytes. By using the Inductive Coupled Plasma Emission Spectrometer(ICP), X-ray photoelectron spectroscopy(XPS), Thermogravimetric-differential scanning calorimetry(TG-DSC) and Accelerating Rate Calorimeter(ARC), we show that an optimized electrolyte can effectively promote the formation of a protective interfacial layer on two electrodes, which not only retards parasitic reactions between the electrodes and electrolyte but also suppresses dissolution of metal ions from the cathode. With an optimized electrolyte, a NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)/hard carbon cell can attain 56.16% capacity retention under the low temperature of -40℃, and can be able to retain 80%capacity retention after more than 2500 cycles while presenting excellent thermal safety.

Preparation and Acid Catalytic Activity of TiO2 Grafted Silica MCM-41 with Sulfate Treatment

有或没有硫酸盐处理的 TiO2 grafted 硅石 MCM-41 催化剂被准备。这些材料的结构、酸的性质被 XRD， N2 吸附解吸附作用，元素分析，热分析，拉曼和 FTIR 大小调查。他们的酸催化的活动用 pseudoionone 的环合反应被评估。获得的材料拥有秩序井然的 mesostructure，这被发现，并且 grafted TiO2 部件在高度驱散的非结晶的形式。没有硫酸化的 T/MCM41 包含了仅仅路易斯酸地点，当时 Br ? nsted 和路易斯酸味显著地为 sulfated 材料 ST/MCM41 和 d-ST/MCM41 被改进。T/MCM-41 不为 pseudoionone 的环合反应是活跃的，但是 ST/MCM-41 和 d-ST/MCM-41 拥有了有利催化活动。ST/MCM-41 的催化表演与 Amberlyst-15 的商业稳固的酸催化剂的是可比较的，并且比 d-ST/MCM-41 的好，尽管后者经历了第二个 TiO2 grafting 过程并且因此有更高的 Ti 和 S，满足。在 ST/MCM-41 和 Si-O-Ti 债券上的 Si 和 S=O 的双边的正式就职效果的 Si-O-Ti-O-S=O 的特定的表面结构被推测说明它的更高的酸催化活动。

Novel Nano-composites SDC–LiNaSO_4 as Functional Layer for ITSOFC

As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells(ITSOFC), samarium-doped ceria(SDC)–Li Na SO4nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of Li Na SO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of Li Na SO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm-1at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm-2at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–Li Na SO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–Li Na SO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.

Plasma-assisted aerogel interface engineering enables uniform Zn^(2+)flux and fast desolvation kinetics toward zinc metal batteries

The poor reversibility of Zn anodes induced by dendrite growth,surface passivation,and corrosion,severely hinders the practical applicability of Zn metal batteries.To address these issues,a plasmaassisted aerogel(PAG)interface engineering was proposed as efficient ion transport modulator that can simultaneously regulate uniform Zn^(2+)flux and desolvation behavior during battery operation.The PAG with ordered mesopores acted as an ion sieve to homogenize Zn deposition and accelerate Zn^(2+)flux,which is favorable for corrosion resistance and dendrite suppression.Importantly,the plasma-assisted aerogel with abundant hydrophilic groups can facilitate the desolvation kinetics of Zn^(2+)due to the multiple hydrogen-bonding interaction with the activated water molecules,thus accelerating the Zn^(2+)migration kinetics.Consequently,the Zn/Zn cell assembled with PAG-modified separator demonstrates stable plating and stripping behavior(over 1400 h at 1 mA cm^(-2))and high Coulombic efficiency(99.8%at1 mA cm^(-2)after 1100 cycles),and the Zn‖MnO_(2)full cell shows excellent long-term cycling stability and maintains a high capacity of 154.9 mA h g^(-1)after 1000 cycles at 1 A g^(-1).This study provides a feasible approach for the large-scale fabrication of aerogel functionalized separators to realize ultra-stable Zn metal batteries.

Constructing a"pea-pod"-like nanostructure to provide valid conductive matrix and volume change accommodation for silicon anode in lithium ion batteries

A"pea-pod"-like composite of graphene-wrapped silicon nanoparticles(P–Si@GS)was successfully prepared via a new and facial technique utilizing freeze-drying and subsequent solvothermal process.The cross-linked"pods"formed by curled few-layer graphene sheets constituted a conductive network,in which silicon nanoparticles were tightly wrapped.The unique graphene-wrapped structure with mesopores on the surface can effectively enhance the conductivity of silicon,alleviate its volume effect and provide rapid transport channels for electrons and ions,thus resulting in excellent electrochemical performance.The strategy of combining freeze-drying and solvothermal methods is facile,low-cost and effective,which provides new ideas for the preparation of highperformance graphene-wrapped nanoparticles composites.

Moisture stable and ultrahigh-rate Ni/Mn-based sodium-ion battery cathodes via K^(+)decoration

As one of the most promising cathodes for sodium-ion batteries(SIBs),the layered transition metal oxides have attracted great attentions due to their high specific capacities and facile synthesis.However,their applications are still hindered by the problems of poor moisture stability and sluggish Na^(+)diffusion caused by intrinsic structural Jahn–Teller distortion.Herein,we demonstrate a new approach to settle the above issues through introducing K^(+)into the structures of Ni/Mn-based materials.The physicochemical characterizations reveal that K^(+)induces atomic surface reorganization to form the birnessite-type K_(2)Mn_(4)O_(8).Combining with the phosphate,the mixed coating layer protects the cathodes from moisture and hinders metal dissolution into the electrolyte effectively.Simultaneously,K^(+)substitution at Na site in the bulk structure can not only widen the lattice-spacing for favoring Na^(+)diffusion,but also work as the rivet to restrain the grain crack upon cycling.The as achieved K^(+)-decorated P2-Na_(0.67)Mn_(0.75)Ni_(0.2)5O_(2)(NKMNO@KM/KP)cathodes are tested in both coin cell and pouch cell configurations using Na metal or hard carbon(HC)as anodes.Impressively,the NKMNO@KM/KP||Na half-cell demonstrates a high rate performance of 50 C and outstanding cycling performance of 90.1%capacity retention after 100 cycles at 5 C.Furthermore,the NKMNO@KM/KP||HC fullcell performed a promising energy density of 213.9 Wh·kg^(−1).This performance significantly outperforms most reported state-ofthe-art values.Additionally,by adopting this strategy on O3-NaMn_(0.5)Ni_(0.5)O_(2),we further proved the universality of this method on layered cathodes for SIBs.

Efficacy of integrating short-course chemotherapy with Chinese herbs to treat multi-drug resistant pulmonary tuberculosis in China: a study protocol

Background:Tuberculosis(TB)causedMycobacterium tuberculosis(M.tb)is one of infectious disease that lead a large number of morbidity and mortality all over the world.Although no reliable evidence has been found,it is considered that combining chemotherapeutic drugs with Chinese herbs can significantly improves the cure rate and the clinical therapeutic effect.Methods:Multi-drug resistant pulmonary tuberculosis(MDR-PTB,n=258)patients with Qi-yin deficiency syndrome will be randomly assigned into a treatment group(n=172)or control/placebo group(n=86).The treatment group will receive the chemotherapeutic drugs combined with Chinese herbs granules(1+3 granules),while the control group will receive the chemotherapeutic drugs combined with Chinese herbs placebo(1+3 placebo granules).In addition,MDR-PTB(n=312)patients with Yin deficiency lung heat syndrome will be randomly assigned to a treatment(n=208)or control/placebo(n=104)group.The treatment group will receive the chemotherapeutic regimen combined with Chinese herbs granules(2+4 granules),while the control group will receive the chemotherapeutic drugs and Chinese herbs placebo(2+4 placebo granules).The primary outcome is cure rate,the secondary outcomes included time to sputum culture conversion,lesion absorption rate and cavity closure rate.BACTEC^(TM)MGIT^(TM)automated mycobacterial detection system will be used to evaluate theM.tb infection and drug resistance.Chi-square test and Cox regression will be conducted with SAS 9.4 Statistical software to analyze the data.Discussion:The treatment cycle for MDR-PTB using standardized modern medicine could cause lengthy substantial side effects.Chinese herbs have been used for many years to treat MDR-PTB,but are without high-quality evidence.Hence,it is unknown whether Chinese herbs enhances the clinical therapeutic effect of synthetic drugs for treating MDR-PTB.Therefore,this study will be conducted to evaluate the clinical therapeutic effect of combining Chinese herbs and chemotherapeutic drugs to treat MDR-PTB cases.It will assist in screening new therapeutic drugs and establishing treatment plan that aims to improve the clinical therapeutic effect for MDR-PTB patients.Trial registration This trial was registered at ClinicalTrials.gov(ChiCTR1900027720)on 24 November 2019(prospective registered).

A novel integrated energy systems combining methanol reformed fuel cell with sodium ion battery

Hydrogen safety in storage and transport is one of the major obstacles for the widespread adoption of hydrogen fuel cells,making it critical to assuage public concerns on the safety of compressed hydrogen storage.Methanol in bountiful supply is a promising hydrogen energy carrier.Accordingly,a novel MSR-HT-PEMFC system coupling the hydrogen production via methanol steam reforming(MSR)and energy generation via high temperature proton exchange membrane fuel cell(HT-PEMFC)was firstly introduced by Prof.Zi-Feng Ma from Shanghai Jiaotong University and Prof.Shan-Tung Tu from East China University of Science and Technology,in collaboration with Shanghai Palcan Energy Co.Ltd.The MSRHT-PEMFC system eliminates the potential risks of compressed hydrogen storage.

Effect of doping order on metal-free heteroatoms dual-doped carbon as oxygen reduction electrocatalyst

Metal-free heteroatoms dual-doped carbon has been recognized as one of the most promising Pt/C-substitutes for oxygen reduction reaction(ORR).Herein,we optimize the preparation process by doping order of metal-free heteroatoms to obtain the best electrocatalytic performance through three types of dual-doped carbon,including XC-N(first X doping then N doping),NC-X(first N doping then X doping) and NXC(N and X doping)(X=P,S and F).XC-N has more defect than the other two indicated by Raman spectra.X-ray photoelectron spectrom(XPS) measurements indicate that N and X have been dual-doped into the carbon matrix with different doping contents and modes,Electrocatalytic results,including the potential of ORR peak(Ep),the half-wave potential,the diffusion-limiting current density mainly follows the order of XC-N>NC-X> NXC,Furthermore,the synergistic effect of second atom doping are also compared with the single doped carbon(NC,PC,SC and FC).The differences in electronegativity and atomic radius of these metal-free heteroatoms can affect the defect degree,the doping content and mode of hete roatoms on carbon matrix,induce polarization effect and space effect to affect O2 adsorption and product desorption,ultimately to the ORR electrocatalytic performance.