壳聚糖在二元离子液体中的溶解性及结构

文中研究了壳聚糖在1-烯丙基-3-甲基咪唑氯盐(AmimCl)和1-丁基磺酸-3-甲基咪唑硫酸氢盐(SmimHSO4)按不同质量比组成的二元离子液体中的溶解性,分析了可能的溶解机理,并利用偏光显微镜、红外光谱、热重-差示扫描及X射线衍射等技术表征溶解再生后的壳聚糖结构及性能。结果表明,二元离子液体通过破坏壳聚糖分子链间的氢键作用来溶解壳聚糖,在AmimCl/SmimHSO4(质量比9/1)中110℃溶解2 h的壳聚糖溶解浓度达到6.81%,随着溶解温度上升和时间延长,壳聚糖的溶解浓度和再生后壳聚糖的回潮率均增大,但再生壳聚糖的黏均分子量下降。溶解后再生的壳聚糖晶型结构由α型转变为β型,结晶度从原始壳聚糖的46.76%下降到26.35%,热稳定性也有降低。AmimCl/SmimHSO4二元体系在壳聚糖化学改性与溶解应用方面极具潜力。

Homogeneous bottom-growth of lithium metal anode enabled by double-gradient lithiophilic skeleton

Lithium(Li) metal is considered as the most promising anode material for the next-generation high performance Li batteries.However,the uncontrollable dendritic growth impedes its commercial application.Herein,we design a 3 D Si@carbon nanofibers(CNFs)@ZnO-ZnO-Cu skeleton(SCZ) for guiding the homogeneous bottom-growth of Li metal.The top LixSi@CNFs and bottom LiyZn@CNFs layers could form conductivity and overpotential gradient to avoid the "top-growth" of Li metal.Moreover,the top lithiophilic LixSi@CNFs layer could regulate the nucleation and deposition of Li-ions even if the lithium dendrites grow out of the skeleton under high capacity Li deposition(30 mAh cm^(-2)).As a result,the SCZ-Li||LiFePO_(4) full cell delivers a high capacity of ~104 mAh g^(-1)(~94.82% capacity retention) after 2000 cycles at 5 C, elucidating the potential application of the 3 D double-gradient Li metal composite anode.

A robust Janus bilayer with tailored ionic conductivity and interface stability for stable Li metal anodes

The formation and growth of Li-dendrites caused by inhomogeneous Li deposition severely hinder the commercial applications of Li metal batteries due to the consequence of short-circuiting.Herein,we propose a Janus bilayer composed of black phosphorus(BP)and graphene oxide(GO)as an artificial interface with chemical/mechanical stability and well-regulated Li-ion flux distribution for Li metal anode protection.Owing to the synergy between the fast Li-ion transport of BP in the inner layer and the high mechanical and chemical stability of GO in the outer layer,the GO/BP with good electrolyte wettability acts as a Li-ion regulator that can induce homogeneous growth of Li to suppress the Li dendrites growth.Accordingly,long-term stability(500 h at 1 mA cm^(-2))with a low overpotential of 30 mV is achieved in the symmetric cell with GO/BP-Li anode.Furthermore,the Li–S cell with GO/BP-Li exhibits enhanced cycling performance with a high capacity retention rate of 76.2%over 500 cycles at 1 C.

氧空位提升锂离子电池富锂锰基正极分级多孔微米球的高倍率性能（英文）

富锂锰基正极材料存在首次库仑效率低、倍率性能差以及电压衰减严重等问题,极大地限制了其规模化应用.本文通过在富锂锰基分级多孔微米球的表面构筑氧空位(L@S)成功抑制了首次放电过程中不可逆Li_2O的形成,有效促进了Li^+离子的扩散动力学,从而提高了电极材料的结构稳定性.研究结果表明,L@S正极在0.1 C电流密度下循环的首次库仑效率高达92.3%,放电比容量为292.6 mA h g^-1;在10 C大电流密度下循环100圈后可逆比容量为222 mAhg^-1,容量保持率为95.7%.进一步增大电流密度至20 C时,循环100圈后L@S正极的放电比容量仍高达153 mAh g^-1此外,匹配Li4Ti5012负极组装的全电池在3 C电流密度下循环400圈后的可逆比容量为141 mAh g^-1,电压保持率高达97%.

3D uniform nitrogen-doped carbon skeleton for ultra-stable sodium metal anode

Sodium metal batteries are arousing extensive interest owing to their high energy density,low cost and wide resource.However,the practical development of sodium metal batteries is inherently plagued by the severe volume expansion and the dendrite growth of sodium metal anode during long cycles under high current density.Herein,a simple electrospinning method is applied to construct the uniformly nitrogen-doped porous carbon fiber skeleton and used as three-dimensional(3D)current collector for sodium metal anode,which has high specific surface area(1,098 m^2/g)and strong binding to sodium metal.As a result,nitrogen-doped carbon fiber current collector shows a low sodium deposition overpotential and a highly stable cyclability for 3,500 h with a high coulombic effciency of 99.9%at 2 mA/cm^2 and 2 mAh/cm^2.Moreover,the full cells using carbon coated sodium vanadium phosphate as cathode and sodium pre-plated nitrogen-doped carbon fiber skeleton as hybrid anode can stably cycle for 300 times.These results illustrate an effective strategy to construct a 3D uniformly nitrogen-doped carbon skeleton based sodium metal hybrid anode without the formation of dendrites,which provide a prospect for further development and research of high performance sodium metal batteries.

Direct synthesis of tin spheres/nitrogen-doped porous carbon composite by self-formed template method for enhanced lithium storage

To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process,a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon(Sn/NPC)by pyrolysis of a mixture of disodium stannous citrate and urea.The vital point of this strategy is the formation of Na_(2)CO_(3)templates during pyrolysis.This self-formed Na_(2)CO_(3)acts as porous templates to support the formation of NPC.The obtained NPC provides good electronic conductivity,ample defects,and more active sites.Serving as anode for Li-ion batteries,the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g.Especially,a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g.Additionally,a full cell coupled with LiCoO_(2)as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g.In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms.Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity,and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability.Climbing image nudged elastic band method reveals low Li~+diffusion energy barrier in presence of N atoms,which accounts for the terrific electrochemical properties of Sn/NPC electrode.

Artificial intelligence application in a renewable energy-driven desalination system: A critical review

Artificial intelligence,an emerging technology,widely exists in the field of engineering science and technology.Due to its high efficiency and precision,artificial intelligence is increasingly used in the optimal control of water treatment and seawater desalination.Generally,the design of a desalination system includes four processes:site selection,energy prediction,desalination technology selection and systematic parameter optimization.To a large extent,these choices depend on the experience and relevant criteria of researchers and experts.However,facing the scientific and technological progress and growing expectations,it is impossible to solve such complex nonlinear problems by simple experience and mathematical models,but artificial intelligence is good at this.In this paper,we synthetically analyzed and summarized the application of artificial intelligence in the field of seawater desalination with renewable energy.Artificial intelligence application in desalination is mainly divided into four aspects:expert decision-making,optimization,prediction and control by sequence.The features of artificial intelligence employed in the design of desalination systems not only realize the maximum of efficiency and minimum of cost,but release the human resources.After analyzing the four processes of desalination,it is found that artificial neural network and genetic algorithm are more widespread and mature than other algorithms in dealing with multi-objective nonlinear problems.This paper overviewed the application of artificial intelligence technologies in decision-making,optimization,prediction and control throughout the four processes of desalination designs.Finally,the application and future development prospect of artificial intelligence in the field of seawater desalination are summarized.