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Lithium metal, with the highest specific capacity (3860 mAh g−1) and the lowest reduction potential (− 3.04 V vs. standard hydrogen electrode), is considered as an ideal anode for the next-generation lithium-metal batteries with high energy density. However, the poor cycling performance and safety problems seriously restrict the commercial application of lithium-metal batteries. Herein, a three-dimensional (3D) porous nitrogen-doped graphene aerogel (NGA) was prepared by a hydrothermal method followed with lyophilization and high-temperature treatment to guide the uniform and dendrite-free Li deposition. On the one hand, the 3D porous structure with a large specific surface area can reduce the effective current density of the electrode, decrease the Li nucleation overpotential, and provide large spaces for Li deposition. On the other hand, the doped nitrogen atoms could provide strong affinity between Li and the NGA substrate for uniform Li deposition. Based on the synergistic effect of the above-mentioned two reasons, the Coulombic efficiency of Li deposition on NGA electrode can remain as high as 99% for over 150 cycles at a constant current density of 0.5 mA cm−2 with a fixed capacity of 1 mAh cm−2. The LiFePO4 (LFP) full cells with Li-NGA anode also exhibit excellent cycling performance and rate performance, indicating NGA has a good application prospect toward high-performance lithium-metal anode. [ABSTRACT FROM AUTHOR]

A LiAlCl4·3SO2-NaAlCl4·2SO2 binary inorganic electrolyte was prepared by using NaAlCl4·2SO2 as the functional additive and mixing with LiAlCl4·3SO2. The obtained LiAlCl4·3SO2-NaAlCl4·2SO2 not only has good non-flammability but also exhibits improved electrochemical performance for Li-metal batteries. With the addition of NaAlCl4·2SO2, the fabricated Li/Cu cells using mixed inorganic electrolyte display higher average coulombic efficiency and more excellent cycling stability. Through scanning electron microscopy (SEM) characterization, it is demonstrated that the surficial morphology of Li-deposited layer is smoother in LiAlCl4·3SO2-NaAlCl4·2SO2 binary electrolyte system than pure LiAlCl4·3SO2. Furthermore, the fabricated Li/graphite cells using LiAlCl4·3SO2-NaAlCl4·2SO2 binary electrolyte also show higher specific capacity and better cycling stability than using pure LiAlCl4·3SO2 electrolyte as well as the conventional organic electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate mixed solvent with 1:1 in volume). Consequently, LiAlCl4·3SO2-NaAlCl4·2SO2 is proposed to have great potential for the safe and high-performance Li-metal batteries. [ABSTRACT FROM AUTHOR]

LiAlCl4·3SO2 is a promising electrolyte used for Li metal batteries. At room and low temperature, a stable solid electrolyte interface film can be formed in LiAlCl4·3SO2 to achieve favorable protection for Li metal anodes. Here, Li|Cu cells with SO2-based inorganic electrolyte (LiAlCl4·3SO2) display higher average coulombic efficiency and more excellent cycling stability compared with a conventional organic electrolyte. Moreover, at 0.5 mA cm−2, the coulombic efficiency of Li|Cu cells with LiAlCl4·3SO2 electrolyte can reach 95% at − 20 °C, while the coulombic efficiency of the conventional organic electrolyte at − 20 °C is only about 79%. Furthermore, LiAlCl4·3SO2 electrolyte is non-combustible. Based on all the experimental results, LiAlCl4·3SO2 is a promising electrolyte candidate for safe Li metal batteries. [ABSTRACT FROM AUTHOR]

Metal lithium anodes are quite promising for next-generation batteries due to their high energy density and low voltage, which has attracted numerous attention of the researchers. However, the main challenge for lithium anodes still lies on their serious dendrite problems, leading to the poor cycling stabilities. Here, we introduced poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP) composite film combined with nano alumina (nano-Al2O3), lithium fluoride (LiF) and lithiumbis(trifluoromethanesulphonyl)imide (LiTFSI), as a stable protective layer (SPL), to coat on the surface of cooper current collector, which was beneficial to improve the cycling stabilities of the fabricated lithium–copper (Li–Cu) half-cell. The copper foil electrode modified with the protective layer exhibited a much enhanced cycling performance compared with the one without modification, which did not show obvious capacity decay after 250 cycles at the current density of 0.5 mA/cm2 for 2 h. From SEM and XPS characterizations, it had to be found that the preset protective composite layer kept a stable structure during the charge and discharge process, which guaranteed the achieved stable cycling performance. In addition, a full battery system based on modified copper foil anode and LiFePO4 cathode also constructed and presented a good cycling performance. [ABSTRACT FROM AUTHOR]

When two 42-mm 6082Al plates were welded by friction stir welding (FSW), a discontinuously distributing groove defect is formed on the surface of the joint. Subsequently, the FSW repairing process was conducted at the defect location. The influence of the repairing process on the microstructures and mechanical properties of the joints were studied, and a description of the softening mechanism of the repaired joints is provided. The results show that TMAZ at the advance side is the weakest zone of the as-welded joints. The repairing process increases the heat input into the joints and thus promotes the coarsening and transformation of the precipitates in the joints, which further weakens the repaired joints. The average tensile strength of the joints repaired with a 24-mm pin is 205 MPa, which is 91% of that of the as-welded joint. The tensile strength generally increases when the size of the repaired pin decreases. The average tensile strength of the joints repaired with an 8-mm pin is 220 MPa, which is equivalent to the initial joints. [ABSTRACT FROM AUTHOR]

The performance of LiFePO4 (LFP)/graphite batteries would decline during floating-charge and cycling aging. The main aging factors are same for these two application modes. However, there are differences between the aging rates, aging factors on positive, and negative electrodes when batteries undergone floating-charge and cycling mode. In this work, LFP/graphite batteries were assembled and tested under different floating-charge and cycling conditions. By combining XRD and SEM techniques, it can be found that the capacity loss rates for cycling mode were larger than floating-charge mode. On the other hand, although both the electrode structures of LFP and graphite would deteriorate for both cycling and floating-charge mode, the electrochemical performance of LFP positive electrode were relatively more stable than graphite electrode. Moreover, the influence of the deterioration of graphite electrode on the separator were also studied and analyzed. And the differences of aging mechanism for floating-charge and cycling mode were also discussed. [ABSTRACT FROM AUTHOR]

We propose an integrated system for simultaneous ammonia recovery, ammonia pretreatment, biogas upgrading, and fertiliser production in biogas production. Ammonia stripping and absorbing played an important role as they significantly affected the ammonia recovery and biogas upgrading performance. Ammonia stripping with biogas was used to remove ammonia from biogas slurry at various conditions. The ammonia removal efficiency reached 99.30% at 10% CO 2 content, 90 °C and 6 h stripping time. Ammonia absorption of ammonia-bearing biogas achieved crystalline ammonium and biogas upgrading. The obtained crystalline ammonium was used for recovering ammonia. The ammonia pretreatment and anaerobic digestion results showed that wheat straw pretreated with 0.70% ammonia concentration and 105 °C obtained the highest biogas yield of 538.1 mL g−1, which was 31.9% higher than untreated wheat straw. The process in this study shows a great potential in biogas production by recycling ammonia for pretreatment of feedstocks and biogas purification associated with producing fertilisers. Highlights • Proposed an integrated system, including ammonia pretreatment and ammonia recovery. • Obtained the crystalline ammonium bicarbonate by ammonia stripping and absorbing. • Ammonia is used for both pretreatment of feedstocks and biogas purification. • The maximum biogas yield of 538.1 mL g−1 was 31.9% higher than control. [ABSTRACT FROM AUTHOR]

6082-T6 aluminum alloy plate with thickness of 42mm was butt welded by friction stir welding (FSW) from two sides. The microstructures of the joints exhibited different grain sizes because of unequal frictional heating and plastic flow during FSW process. The transition from the heat affected zone (HAZ) to the nugget zone (NZ) in thermos-mechanical affected zone of advancing side (AS-TMAZ) was more sudden than thermos-mechanical affected zone of retreating side (RS-TMAZ). Kissing bond (KB) defect throughout the entire FSW joint was displayed both at the grain boundary and in the interior of the grain with semi-continuous bands. KB had no direct effect on tensile properties. Vickers hardness of the FSW joint was lower than the BM because its high heat input, dissolved and coarsened precipitates and little to the grain size after FSW. Hardness distribution of double-sided welding joint showed X-shaped area softening characteristics, that is to say the lowest hardness was the junction of two welding joint of NZ and the junction of TMAZ and HAZ. The tensile fracture position occurred in the lowest hardness region of the FSW joint, and it did not occur in the KB defect position. [ABSTRACT FROM AUTHOR]

This paper presents a kinematic and dynamic model which can be used to simulate telescopic crane slewing, luffing, telescoping, lifting and pulling load movements. The crane joint motion can be described as smooth continuous sine cosine function. The crane dynamic equations are derived by Lagrange method. The lifting rope length from boom tip to hooks described as a time-variant constraint equation. The dynamic equations and the constraint equation form differential algebraic equations which can be solved by constraint stabilization method. The validity and correctness of the telescopic crane model is verified through an example. We prospect the model can be used for the research on compound motion control and lifting scheme design of telescopic crane in the virtual reality. [ABSTRACT FROM AUTHOR]

The tunnel defect formed in friction stir weld would dramatically push the mechanical properties of joints into deterioration. In this study, friction stir welding process was adopted to repair the joints of 7N01 aluminum alloy with tunnel defect. The effects of friction stir repair welding process on the microstructure and mechanical properties were comprehensively investigated. Microstructure of the repaired joints shows that the grain size in nugget zone decreases slightly while the recrystallization in the retreating side of thermo-mechanically affected zone is intensified as the joints are repaired. The microhardness of the repaired joints declined slightly compared with the defective joint. However, the yield strength and tensile strength increase and recover to the values of the joints free of defect. The longitudinal residual stress in weld zone increased remarkably as the repair times increase. Compared with the once repaired joint, yield strength and tensile strength of the twice repaired joint reduced slightly, and the throat thickness also reduced during the repeated repair welding process. Therefore, the times of repair welding applied should be limited actually. [ABSTRACT FROM AUTHOR]

A LiFePO4 (LFP)/lithium polysulfide (Li2Sn) hybrid system was designed using a LFP cathode and a Li2Sn-added electrolyte to improve the Li-ion storage performance. In the LFP cathode, a commercial LFP product was introduced as the active material. And the Li2Sn-added electrolyte was prepared through a facile liquid-phase process. Benefiting from the synergistic effect for energy-storage between the LFP component and the Li2Sn component, the designed LFP/Li2Sn hybrid system exhibited a large specific capacity (439 mA h g−1 at 0.2C), good rate performance (323 mA h g−1 at 2C) and stable cycling property (82% capacity retention over 200 cycles). It is believed that the designed LFP/Li2Sn hybrid system and the proposed hybrid energy-storage concept could advance the development of electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Cattle manure with different moisture contents was carbonized under different temperatures to investigate the products distribution and cattle manure char’s properties. And the cattle manure char’s gasification performance was compared with cattle manure to explore the manure char’s gasification potential. Results showed that temperature and moisture content exerted a strong influence on products distribution and cattle manure char properties. Manure char yield decreased and gas yield increased with increasing temperature. Moisture content of 56.20% was favor to improve the gas yield, while moisture content of 85.12% promote the liquid yield. Carbon content in manure char decreased as the moisture content increased, and it increased as temperature increased. The product distribution and elemental analysis results indicated that the C in cattle manure was converted to gas phase at 56.20% moisture content and to liquid phase at 85.12% moisture content. Steam gasification results showed that syngas and hydrogen yields from manure char increased by 1.79 and 2.27 times, respectively, comparing with gasification of cattle manure. And weight loss of manure char (52.00%) was lower than that of cattle manure (83.70%). These indicated that using cattle manure char as gasification feedstock can enhance the reduction of tars in the product gas. In addition, the H 2 concentration from manure char reached 59.22%. Therefore, the cattle manure char is a good feedstock for producing hydrogen. [ABSTRACT FROM AUTHOR]

• Proposed a warning index to assess the groundwater deficit (G sci). • Analyzed the precipitation threshold for the occurrence of each G sci grade. • Analyzed the probability of G sci under different precipitation conditions. Groundwater resources are closely related to climate change. Evaluating the groundwater deficit and its variation characteristics under climate change is necessary to understand the risk associated with enhanced groundwater recovery solutions and to provide supporting information for choosing the best technology and risk-reducing measures to implement. In this study, by using the CROPWAT model and copula theory, (1) we developed a groundwater deficit index (G sci) for agricultural requirements that assesses the risk to groundwater resources imposed by precipitation changes on the North China Plain (NCP), and the four grades of G sci were high deficit, moderate deficit, low deficit, and no deficit. (2) We estimated G sci on the NCP for the period 1971–2020 by applying the climatic, soil, crop phenological, and hydrogeology data to the developed index. (3) The occurrence probability of each G sci grade was evaluated. In the years with abundant precipitation, the occurrence probabilities of no-deficit events were 1, 0, 0, 0, 0.36, 0.56, and 0 on the Yanshan Plain, Taihang-Hebei Plain, Taihang-Henan Plain, Central-Hebei Plain, Central-Shandong Plain, Central-Henan Plain, and Coastal Plain, respectively. (4) The effective precipitation threshold for the occurrence of each G sci grade was calculated, and the effective precipitation thresholds for the occurrence of no-deficit events were 495 mm, 595 mm, 525 mm, 400 mm, 455 mm, and 555 mm on the Taihang-Hebei Plain, Taihang-Henan Plain, Central-Hebei Plain, Central-Henan Plain, Central-Shandong Plain, and Coastal Plain, respectively. Our findings are useful for assessing the impacts of precipitation changes on groundwater resources and provide a further basis for the design of groundwater resource management strategies with respect to climate change, especially in water‐limited arid agricultural regions. [ABSTRACT FROM AUTHOR]