The hydrolysis of MgH2 delivers high hydrogen capacity (15.2 wt%), which is very attractive for real-time hydrogen supply. However, the formation of a surface passivation Mg(OH)2 layer and the large excess of H2O required to ensure complete hydrolysis are two key challenges for the MgH2 hydrolysis systems. Now, a low-cost method is reported to synthesize MgH2@Mg(BH4)2 composite via ball-milling MgH2 with cheap and widely available B2O3 (or B(OH)3). By adding small amounts of B2O3, the in-situ formed Mg(BH4)2 could significantly promote the hydrolysis of MgH2. In particular, the MgH2–10 wt% B2O3 composite releases 1330.7 mL·g−1 H2 (close to 80% theoretical hydrogen generation H2) in H2O and 1520.4 mL·g−1 H2 (about 95%) in 0.5 M MgCl2 in 60 min at 26 °C with hydrolysis rate of 736.9 mL·g−1·min−1 and 960.9 mL·g−1·min−1 H2 during the first minute of the hydrolysis, respectively. In addition, the MgCl2 solution allows repeated use by filtering and exhibits high cycle stability (20 cycles), therefore leading to much reduced capacity loss caused by the excess H2O. We show that by introducing B2O3 and recycling the 0.5 M MgCl2 solution, the system hydrogen capacity can approach 5.9 wt%, providing a promising hydrogen generation scheme to supply hydrogen to the fuel cells.

V-based BCC solid-solution alloys have been considered as promising hydrogen storage materials due to their high hydrogen storage capacity; however, the low effective hydrogen desorption capacity and high cost of pure V have limited their practical application in fuel cell vehicles or devices. Herein, a low-V TiCr1.2(V-Fe0.203)0.6 hydrogen storage alloy with a hydrogen storage capacity of 3.35 wt% has been developed by using a low-cost FeV80 as raw material. To further increase the effective hydrogen desorption capacity, cheap Mn is first used to partially substitute for Cr in FeV80-based alloy. The Mn substitution alloy achieves an effective hydrogen desorption capacity of 2.07 wt% cutting-off at 0.1 MPa with good activation performance. It is ascribed that the minor alloying of Mn increases thedehydrogenation plateau pressure and reduces the hysteresis and the enthalpy change value. The dehydrogenation enthalpy decreases from 34.84 kJ/mol to 31.51 kJ/mol. The synergistic effect of Mn and Fe increases the abundance of the C14 Laves phase, which plays a catalytic role in hydrogen absorption and desorption. The cost of TiCr1.1Mn0.1(V-Fe0.203)0.6 alloy is much lower than that of using pure V, and even lower than some AB2 alloys based on cost estimation. The results of this study would provide a reference for the application of low-cost Ti-Cr-(FeV80) alloys for hydrogen storage.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Intermetallic high-entropy alloys (HEAs) with C14 Laves phase structure have shown promise as hydrogen storage materials due to their ability to maintain the advantages of the AB2-type hydrogen storage alloys while offering the potential for the improvement of hydrogen storage properties through the use of multi-principal elements. However, some intermetallic HEAs are limited in their ability to scale-up production using the lowcost induction melting method and reversible hydrogen storage at room temperature due to their extremely low equilibrium desorption pressure. In this work, intermetallic HEAs with reversible room-temperature hydrogen storage are designed using an empirical model based on calculation of the electronic and geometrical factors. An orthogonal experiment was conducted to optimize the composition and the optimal (Ti1.3Zr0.7)1.1Cr1.1Mn1.8Fe0.3Co0.4V0.4 HEA with a single C14 Laves phase was found to exhibit the best overall hydrogen performance. It can reversibly store 1.84 wt% hydrogen with a relatively low plateau hysteresis factor (0.71) and slope factor (0.89) at a temperature of 15 degrees C. The dehydrogenation enthalpy and entropy of the optimal HEA were determined to be 35.0 kJ mol-1 and 115.3 J mol-1 K-1, respectively. To reduce the cost of HEAs, FeV80 was employed to replace the V. It was found that the optimal HEA could be successfully scaled-up for production, and our findings demonstrate the potential of intermetallic HEAs for efficient hydrogen storage.

Innovatively adopting a dual thermally stabilized synergistic strategy, a stable Al-doped and heat-resistant MoO 3 -coated cathode, LiNi 0.928 Co 0.072 O 2 , was fabricated.

Low-cost low vanadium (low-V) hydrogen storage materials have high reversible capacities (>2.0 wt%) under moderate conditions, however, they suffer from drastic capacity decay during cycling. In this work, a series of TiCr1.1M0.1(V-Fe)(0.6) (M = Mn, Mo and Nb) alloys are prepared by elemental alloying on the basis of the low-cost, low-V alloy TiCr1.2(V-Fe)(0.6) alloy, and the modification mechanism of the elemental alloying on the cycling durability of the alloy is systematically investigated. In 100 cycles, the results demonstrated that the original alloy TiCr1.2(V-Fe) (0.6) suffered from poor desorption capacity (1.13 wt%) and lowly capacity retention rate (60.43%). Compared to the addition of Mn and Nb, TiCr1.1Mo0.1(V-Fe)(0.6) obtained higher cyclic hydrogen storage capacity (1.32 wt%) and capacity retention (68.04%). In addition, it is found that the addition of Mo can inhibit the formation of the secondary phase during the cycling, and the abundance of the C14 Laves phase maintained at only 2.47% after 100 cycles. According to the microstructural analysis of the alloys during cycling, it is found that the decrease in grain size, the accumulation of micro strain and dislocation density, and the degree of particle pulverization seriously affect the cycling durability of the alloys, resulting in a drastic decrease in the dehydrogenation cycling capacity. Finally, it should be noted that although the improvement in cycle durability with Mo alloying is limited, it is still a positive reference for developing low-cost low-V alloys with good cycle durability.

The large-scale application of nickel-rich ternary cathode materials is still limited by their inherent defects such as structural stability, cycling and rate performance. Herein a novel single-crystalline nickel-rich ternary cathode material dual-doped with Al and Ce is deliberately designed. Both of them are evenly distributed in the materials and an alpha-LiAlO2 layer evolves on the surface, which largely alleviate the corrosion from the electrolyte and facilitate the Li+ diffusion. Furthermore, the TM-O is partially replaced to form the Al-O and Ce-O bonds, which can reduce the degree of Li+/Ni2+ mixing and then stabilize the layered structure to certain extent. The dualdoped single-crystal nickel-rich ternary cathode material shows superior cycle stability and large-current discharge capacity to the undoped counterpart. After 100 cycles at 1C and a high cutoff voltage of 4.5 V, the target material yields a specific capacity of 160.95 mA h g-1, with a capacity retention of up to 85.38 %. More importantly, the alpha-LiAlO2-coated layer significantly facilitates the rate performance with a specific capacity of 164.5 mA h g-1 at 10C. The dual -doping strategy in this work provides a feasible pathway to improve the electrochemical performance of nickel -rich single -crystalline ternary cathode material.

The silicon suboxide (SiO) anode material is considered to be a promising anode material of Lithium-ion batteries (LIBs), because of its high theoretical capacity. However, there are severe problems for SiO, including the huge volume change (200%), the low electrical conductivity and the low first Coulombic efficiency. In order to solve those problems, a ternary composite ((SiOx/G/SnO2)@C) (G denotes graphite) with carbon coating layer is prepared by ball milling, spray drying and sintering. In the composite, graphite as one part of the active materials, can improve the Coulombic efficiency and control volume change of SiOx. To further restrain the high-volume change of SiOx, the carbon coating layer is designed. In particular, owing to the presence of SnO2, a better electrochemical performance for (SiOx/G/SnO2)@C is obtained. The results show that the first charging capacity of (SiOx/G/SnO2)@C can reach 382.6 mAh g−1 at current density of 100 mA g−1 and the Coulombic efficiency is improved from 62.2% to 74.9%. After 110 cycles, the charging capacity is 424.6 mAh g−1 and the capacity retention rate is 103.9%. In addition, after 90 cycles of rate performance test, (SiOx/G/SnO2)@C exhibited the highest capacity retention of 104.7%.

To solve the major defects of SiOx-based anode materials, composite materials with different Si-Fe content and SnO2 were deliberately prepared via a tandem strategy involving mechanical ball milling, spray drying, and high-temperature pyrolysis in this paper. Furthermore, the phase structures, microscopic morphologies, and electrochemical properties of as-obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), and galvanostatic charge-discharge test system. The electrochemical results show that the composite containing a mass fraction of 5% Si-Fe possesses a relatively good comprehensive electrochemical performance with a charging capacity of 443.4 mAh center dot g(-1) and the first Coulombic efficiency of 75.2%. After 310 cycles, the charging capacity still retained 369.1 mAh center dot g(-1), and the capacity retention rate was up to 81.0%. Meanwhile, the lithium diffusion rate is remarkably improved after Si-Fe incorporation.

Nickel-rich LiNi(x)Co(y)MnzO(2) (x + y + z = 1) cathode materials have been extensively studied due to their improved energy density and reduced cost in comparison to conventional layered oxides (LiCoO2) and perovskite-type compounds (LiFePO4). However, the further commercialization of polycrystalline nickel-rich layered cathodes are severely hampered by entrenched particle microcracking that evolves mainly from the randomly oriented grain boundaries in the primary particles. Herein, an environmental-friendly LiOH center dot H2O/ Li2CO3 binary molten-salt method is introduced to synthesize single-crystal LiNi0.88Co0.09Mn0.03O2 with good crystallinity and dispersion, and the possible growth mechanism of the particles is inferred. The sample prepared at a lithium ratio of 1.7 (SC1.7) shows a lower degree of cation mixing and larger lithium layer spacing compared to control polycrystalline sample (PC), and the residual alkali is effectively removed from the surface of single crystal particles. These features enable SC1.7 to maintain robust structural stability during cycling, with the cycle retention at 1C rate and a voltage of 4.5 V to be 86.73% after 100 cycles. The desirable performance is rationally derived from the significant inhibition of microcracks in particles, and reduction of parasitic reactions. The unique binary molten-salt strategy provides a new avenue for the design of high-performance high-nickel cathode materials in lithium-ion batteries.

In order to promote the practical application of hydrogen storage system,it is necessary to carry on research on large-scale application hydrogen storage alloys.Among the hydrogen storage alloy,Ti-Mn based AB 2 type hydrogen storage alloy,with high hydrogen storage capacity,adjustable platform pressure,and low raw materials price,is a suitable candidate for large-scale application of hydrogen storage materials.However,Ti-Mn based hydrogen storage alloy suffers from some questions:（1） harsh alloy activation conditions;（2） high platform pressure of hydrogen absorption/desorption;（3） high slope and hysteresis factor of hydrogen absorption/desorption platform.Element substitution is an effective method to improve the properties of Ti-Mn based hydrogen storage alloy.To develop Ti-Mn based hydrogen storage alloy for solid state hydrogen storage system,the effects of adding V-Fe,tuning Mn content and replacing V-Fe with pure metal V and Fe on the properties of hydrogen storage alloys Ti 0.95 Zr 0.05 Mn 2 were investigated systematically.The activation properties of Ti-Mn based hydrogen storage alloy could be tuned by adding V-Fe,while the platform pressure and platform features （slope and hysteresis） could be moderated by tuning Mn content,and replacing V-Fe with pure metal V and Fe.Ti-Mn based hydrogen storage alloys were synthesized by vacuum arc melting.Additionally,there was 4%more Mn in the raw materials to make up the loss during the melting.Before testing,the alloys were crushed by hammer to particles less than 150μm.The phases of the alloys were characterized by X-ray diffraction （XRD）,while the lattice parameters were computed by Fundamental Parameters Approach （TOPAS-5 Academic software）.The hydrogen storage properties of alloy were characterized by the pressure-component-temperature （P-C-T） curves,which were tested by Sieverts type hydrogen storage material performance test system.Before P-C-T testing,alloys were activated twice at the activation condition:vacuum at 80℃for 30 min,and then hydrogenation at 5 MPa H 2 and 20℃.The results showed that after element substitution,alloys remained C14-typed Laves phase （P63/mmc;No.194）,but the lattice parameters and hydrogen storage properties were different.By adding V-Fe,the lattice parameters of hydrogen storage alloys were increased and the activation properties of hydrogen storage alloys were improved.Ti 0.95 Zr 0.05 Mn 2 and Ti 0.95 Zr 0.05 Mn 1.8 （V-Fe） 0.21 could not be activated by vacuum at 250℃and then hydrogenation at 15 MPa H 2 and 20℃，but Ti 0.95 Zr 0.05 Mn 1.5 （V-Fe） 0.52 and Ti 0.95 Zr 0.05 Mn 1.0 （V-Fe） 1.04 could be activated at the activation condition above.Hydrogen atom could rapidly diffuse en in V element,so the addition of V-Fe could effectively improve the activation properties of alloy.However,excessive addition of V-Fe dramatically reduced the hydrogen platform pressure and storage capacity.The hydrogen absorption platform pressure of Ti 0.95 Zr 0.05 Mn 1.5 （V-Fe） 0.52 was 1.124 MPa,while that of Ti 0.95 Zr 0.05 Mn 1.0 （V-Fe） 1.04 was only 0.11 MPa.A series of alloys with different Mn contents (Mn 1.3～1.5 ) were prepared to study the role of Mn on the hydrogen storage properties.By increasing the content of Mn,the platform pressure of hydrogen absorption/desorption increased,while the hydrogen storage capacity increased in the early stages and then decreased.According to the Local Environment Model,there were three kinds of tetrahedral interstices in AB 2 type hydrogen storage alloy:A 2 B 2 （large,number 12）,AB 3 （middle,number 4） and B 4 （small,number 1） tetrahedral interstice.When the alloy was hydrogenation,the large A 2 B 2 tetrahedral interstices were occupied by hydrogen atom firstly and then AB 3 tetrahedral interstices,while the small B 4 tetrahedral interstices were hardly occupied by hydrogen atom.When there was a slight excess of elements in Site A （B/A=1.92 and 1.98 （mole ratios））,some B 4 tetrahedral interstices were changed into AB 3 tetrahedral interstices,and the hydrogen storage capacity was enhanced.Due to the larger atomic radius of Site A element (R Ti =0.147 nm,R Zr =0.160 nm,R being atomic redius),the excess Site A element leads to the larger lattice parameter of the alloy,resulting in the moderate platform pressure and low platform slope and hysteresis.Thus,Ti 0.95 Zr 0.05 Mn 1.46 （V-Fe） 0.52 with 1.80%hydrogen storage capacity,and hydrogen desorption platform of 0.718 MPa,had the best comprehensive hydrogen storage properties in this series alloys.Furthermore,it had the lowest scope factor of 0.754 in hydrogen desorption platform.By replacing V-Fe alloy by pure metal V and Fe,the properties of hydrogen storage alloy were further improved.After the replacement of V and Fe,the hydrogen storage capacities were increased and the hydrogen absorption and desorption platforms reduced.As the Fe/V ratio increased,the hydrogen absorption and desorption platform pressures increased,while the maximum hydrogen capacity and the platform slope decreased.Among the alloys,Ti 0.95 Zr 0.05 Mn 1.46 V 0.39 Fe 0.13 with the highest hydrogen storage capacity of 1.83%hydrogen desorption platform of 0.751 MPa,and scope factor of 0.567 in hydrogen desorption platform,had the best comprehensive properties.In summary,the activation properties of alloy could be improved by adding V-Fe,and the platform pressure and platform features could be moderated by tuning Mn content.

针对硅氧基负极材料的主要缺陷,在SiOx/石墨基负极材料中巧妙地引入了Si-Fe、SnO2合金化合物,以改善其电化学性能,并通过机械球磨、喷雾干燥和高温热解策略制备了一系列硅氧基复合负极材料.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱仪(EDS)和恒流充放电测试仪对复合材料的物相、微观形貌及电化学性能进行了表征.电化学测试结果表明,复合质量分数5％Si-Fe的目标材料充电容量高达443.4 mAh·g-1,首次库仑效率达75.2％,循环310圈之后容量仍有369.1 mAh·g-1,容量保持率为81.0％(相对第11圈);同时,经Si-Fe复合之后,锂离子扩散速率得到了明显改善.

Magnesium hydride (MgH2) is one of the most promising candidates for hydrogen generation materials due to the benign byproduct Mg(OH)2. However, the low solubility of Mg(OH)2 inevitably causes sluggish hydrolysis kinetics and low hydrogen yield. Herein, a facile strategy is reported to promote the hydrolysis performance of MgH2viain situ formation of metal borohydrides (M(BH4)x). MgH2@M(BH4)x composites are synthesized by ball milling of MgH2 and cheap metaborates. Different ball-milled durations of NaBO2 metaborate and electro-negativities (chi p) of cation elements of metaborates (i.e., KBO2, NaBO2, LiBO2, Ca(BO2)2, and Mg(BO2)2) were compared to reveal that the MgH2-4 mol % NaBO2 composite after 6 h ball milling has the best hydrolysis performance. Specifically, it could release 1597.2 mL g-1 H2 (95% theoretical H2) in 60 min with a fast hydrolysis rate of 1216 mL g-1 min-1 H2 during the first minute of the hydrolysis at 55 degrees C. Our finding is expected to facilitate the application of MgH2 for on-site hydrogen generation.

Ti-V-based BCC solid solution alloys, represented by Ti-Cr-V alloys, are considered as promising hydrogen storage materials due to their high hydrogen storage capacity (over 4 wt%) at room temperature. However, the difficult activation, low effective hydrogen desorption capacities, poor P-C-T plateau characteristics, and high cost remain significant problems for their practical applications. Herein, we present a new compositionally complex (high-entropy) doping strategy which was used to successfully fabricate a low-cost "Laves phase related BCC solid solution", TiCrV0.7(Nb0.2Fe0.2Co0.2Ni0.2Mn0.2)0.2, that exhibits excellent activation performance and high effective hydrogen desorption capacity (C1atme : 2.21 wt%). The main BCC phase ensures high hydrogen storage capacity, while the minor secondary C14 phase plays a catalytic role and thus improves the hydrogen absorption kinetics. Furthermore, we confirmed that there is a synergistic effect of Nb, Fe, Co, Ni, and Mn elements in improving hydrogen storage performance. The dehydrogenation enthalpy Delta H of the heat-treated TiCrV0.7(Nb0.2Fe0.2Co0.2Ni0.2Mn0.2)0.2 is 37.5 kJ mol- 1, which is significantly lower than previously reported Ti-Cr-V based systems, revealing a significant tendency towards easier dehydrogenation with high-entropy doping. This work offers a new alloying method for improving the hydrogen storage performance of hydrogen storage alloys.

富镍正极材料(LiNi0.8Co0.1Mn0.102)具有高容量的优点,是锂离子电池正极材料最有潜力的材料之一.为确定最佳合成条件,本工作研究了合成温度对材料性能的影响,并详细分析了材料电化学性能衰减的原因以及循环过程中材料结构的变化.采用热重/差示扫描量热法(TG/DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(HRTEM)、能谱仪(EDS)、X射线光电子能谱(XPS)等手段对合成的正极材料进行了物化表征,并对其电化学性能进行测试.结果表明,在低温段500℃保温4h,高温段750℃保温14h合成的正极材料NCM750在0.2C首次放电比容量为186.2mAh/g,首次充放电效率为82.5％,1 C放电比容量为185.1 mAh/g,100次循环后仍有175.2 mAh/g,容量保持率为95.2％.在此条件下合成的材料具有结构稳定,粒径均匀,电化学性能优异等优点,本工作对富镍正极材料的合成及结构变化进行研究,有助于加深对材料的了解.

In this work, we report a facile method to regenerate LiBH4 from its ideal hydrolytic product (LiBO2) using MgH2 as the reducing agent under ambient conditions.

LiNixCoyAl1-x-yO2 (NCA), as high nickel cathode material, has a high capacity and is one of the most pro-mising cathode materials for lithium-ion batteries. However, the disadvantages such as more residual li-thium compounds and serious capacity decay have hindered the industrial application of this material. In order to reduce the residual lithium compound on the surface of the material and restrain the capacity degradation, we designed and prepared a high nickel cathode material by pretreatment washing and subsequent spray drying, which has high cycle life and high discharge specific capacity. Compared to the first discharge specific capacity of 196.6 mAh g(-1)(0.2 C) for the raw material and 131.4 mAh g(-1) after 100 cycles of 1 C, the discharge specific capacity of the modified sample 2V(2)O(5)@NCA was increased to 210.4 and 163.8 mAh g(-1), respectively. Microstructure observation revealed that V2O5 not only uniformly covers the surface of the secondary particles, but also the presence of electrochemically active LiV3O8, which avoids the direct contact between the active material and electrolyte, thus significantly suppressing the interfacial side reactions between the cathode material and electrolyte and improving the structural stability of the material. Our exploration may pave a way for developing high cycle stability of high nickel cathode materials. (C) 2021 Published by Elsevier B.V.

The anodic oxygen evolution reaction (OER) is a four-electron reaction process with the relatively sluggish kinetics, which has become one of the main factors limiting the efficiency of the hydrogen evolution reaction in water splitting, so it is crucial to improve the kinetics of OER. Herein, a new RuO2-based composite catalyst Co-Ru-Py@500 has been designed with abundant pore spaces formed by the stacking of nanoparticles, where the nanoparticle comprises CoOx/RuO(2 )hybrid species and an encased carbon layer involving holey space. The CoRu-Py@500 possesses a relatively large specific surface area and a higher proportion of hydroxyl species than Ru-Py@500 without the introduction of CoO(x )species. The catalyst Co-Ru-Py@500 shows a smaller onset potential of 1.39 V vs. RHE and overpotential (230 mV@10 mA cm(-2)) than Ru-Py@500, and significantly favorable tafel slope, electrochemical impedance. In addition, the Fe-Ru-Py@500 and Ni-Ru-Py@500 introduced with FeOx or NiOx species are still inferior to Co-Ru-Py@500, but both of them show a better OER activity than Ru-Py@500. Through introducing Co, Fe, and Ni oxidation state species, the catalytic activity of RuO2 can be promoted to varying degrees. The design strategy in this work provides a significant guidance for the rational design of efficient OER catalysts.

Hydrolysis of Mg-based materials is a promising technology for the development of portable hydrogen fuel cells. However, the Mg(OH)2 layer impedes the diffusion of water molecules into inner particles, resulting in sluggish hydrolysis performance. The hydrolysis performances of Mg-based materials (Mg, MgH2, MgH2-BM and MgH2-RBM) with water are effectively improved under light-activation. The hydrolysis performance could be tailored by the light energy (frequency and intensity). The combination of ball-milling and light-activation could further enhance the hydrolysis performance of MgH2. In particular, the hydrolysis yield of MgH2-RBM reached 95.7% of the theoretical yield under 90 W green light-activation. Thus, rasing the light energy (by using purple light and UV, or higher power lights) and the combination of ball-milling could lead to better hydrolysis performance of Mg-based materials. The Mg(OH)2 layer was considered as a barrier to MgH2 hydrolysis of MgH2. Interestingly, under light-activation, the Mg(OH)2 layer can act as a catalyst to enhance the decomposition of MgH2, and improve the hydrolysis yield and kinetics of Mg-based materials.

In this work, Ni0.88Co0.07Al0.05(OH)(2) was synthesized by aluminum isopropoxide hydrolysis of nickel-cobalt hydroxide as raw material. The precursor was fully mixed with lithium source, and spherical LiNi0.88Co0.07Al0.05O2 cathode material was prepared through three sintering conditions. The crystalline structure, morphology and electrochemical performance were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray photoelectronic spectroscopy (XPS) and electrochemical tests. It is found that the synthesized LiNi0.88Co0.07Al0.05O2 after 500 degrees C for 3 h, and 700 degrees C for 14 h has a good comprehensive electrochemical performance. The discharge specific capacity at 0.2C was up to 192.2 mAh.g(-1), the first charge-discharge efficiency was 81.6%, and the discharge specific capacity at 1C was 190.7 mAh.g(-1), and still remain in 141.1 mAh.g(-1) after 100 weeks, which shows the capacity retention rate of 73.4%.