Safe and Stable Lithium Metal Batteries Enabled by an Amide-Based Electrolyte

The formation of lithium dendrites and the safety hazards arising from flammable liquid electrolytes have seriously hindered the development of high-energy-density lithium metal batteries.Herein,an emerging amide-based electrolyte is proposed,containing LiTFSI and butyrolactam in different molar ratios.1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropylether and fluoroethylene carbonate are introduced into the amide-based electrolyte as counter solvent and additives.The well-designed amide-based electrolyte possesses nonflammability,high ionic conductivity,high thermal stability and electrochemical stability(>4.7 V).Besides,an inorganic/organic-rich solid electrolyte interphase with an abundance of LiF,Li3N and Li-N-C is in situ formed,leading to spherical lithium deposition.The formation mechanism and solvation chemistry of amide-based electrolyte are further inves-tigated by molecular dynamics simulations and density functional theory.When applied in Li metal batteries with LiFePO4 and LiMn2O4 cathode,the amide-based electrolyte can enable stable cycling performance at room temperature and 60℃.This study provides a new insight into the development of amide-based electrolytes for lithium metal batteries.

Stable operation of polymer electrolyte-solid-state batteries via lonepair electron fillers

Due to the increasing demand and wide applications of lithium-ion batteries,higher requirements have been placed on the energy density and safety.Polymer solid-state electrolytes have gained significant popularity due to their excellent interface compatibility and safety.However,their applications have been greatly restricted by the high crystallinity at room temperature,which hinders the transport of lithium ions.Herein,we utilize inorganic tubular fillers with abundant lone-pair atoms to reduce the crystallinity of the polyethylene oxide(PEO)solid-state electrolyte membrane and improve its ionic conductivity at room temperature,enabling stable operation of the battery.The tubular lone-pair-rich inorganic fillers play a key role in providing avenues for both internal and external charge transportation.The surface lone-pair electrons facilitate the dissociation and transport of lithium ions,while the internally tubular electron-rich layer attracts ions into the cavities,further enhancing the ion transport.After 100 cycles at room temperature,the lithium battery loaded with this solid-state electrolyte membrane delivers a specific capacity of 141.6 mAh·g−1,which is 51.3%higher compared to the membrane without the fillers.

锂氧电池中基于自支撑Ag/δ-MnO_(2)纳米花正极的可逆LiOH化学

因放电产物对有机电解液具有高攻击性,使得锂-氧电池能量效率低和循环稳定性差的问题一直限制着其实际应用.与典型放电产物过氧化锂相比,氢氧化锂(LiOH)具有更好的化学和电化学稳定性.本文通过在碳纸上原位生长嵌有纳米银的花状二氧化锰作为锂-氧电池的正极(Ag/δ-MnO_(2)@CP),并证明了它能催化LiOH的可逆生成和分解.原位拉曼测试和理论计算表明Ag/δ-MnO_(2)催化放电中间体LiO2*与水分子解离的H+反应最终生成LiOH.以Ag/δ-MnO_(2)@CP为正极的锂-氧电池在潮湿氧气环境下表现出更高的比容量和放电平台.在电流密度为200 mA g^(−1)时,锂-氧电池的过电位仅为0.5 V,在500 mA h g^(−1)的限制比容量下可循环867圈.该工作为研究固相催化剂在锂-氧电池中的作用提供了新的思路,并将促进基于LiOH放电产物的锂-氧电池的实际应用.

Walnut-inspired microsized porous silicon/graphene core-shell composites for high-performance lithium-ion battery anodes

Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide （P-Si/rGO） core-shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh-g-1 at a current density of 1,000 mA-g-1, 1,600 mAh.g-1 at 2,000 mA-g-1, 1,500 mAh-g 1 at 3,000 mA-g-1, 1,200 mAh-g-1 at 4,000 mA.g-1, and 950 mAh.g~ at 5,000 mA.g-~, and maintain a value of 1,258 mAh.g-~ after 300 cycles at a current density of 1,000 mA-g 1. Their excellent rate performance and cycling stability can be attributed to the unique structural design： 1） The graphene shell dramatically improves the conductivity and stabilizes the solid- electrolyte interface layers; 2） the inner porous structure supplies sufficient space for silicon expansion; 3） the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.

Simultaneous dissipation of trichloroethene and arsenic from co-contaminated groundwater by coupling biodechlorination and biodetoxification with assistance of biochar

Co-contamination of groundwater with trichloroethene(TCE)and arsenic(As)is a widespread problem in industrial sites.The simultaneous biological removal of As and TCE has not yet been developed.This study incorporated biochar into anaerobic dechlorination system to achieve a greatly accelerated dissipation and co-removal of TCE and As.Biochar eliminated microbial lag(6 days)and achieved a 100%TCE removal within 12 days even at a relatively high initial concentration(TCE:30 mg L^(−1);As(V):4 mg L^(−1)),while without biochar,only 75%TCE was removed until day 18.Bio-char adsorbed TCE and the intermediate products allowing them to be degraded on its surface gradually,maintaining a high metabolic activity of microbes.Biochar facilitated the preferential colonization of its surfaces by dechlorinating microorganisms(Clostridium and Dehalococcoides)and suppressed hydrogen-competing microorganisms(Desulfo-vibrio)in water.Biochar itself cannot adsorb As,however,separation of biochar carrying the As-laden microorgan-isms achieved 50-70%As-removal from groundwater.The biochar-amended incubations were found to be enriched with microbes possessing more crucial As-transforming genes(K00537-arsC and K07755-AS3MT),and upregulated amino acid metabolism,thus enhancing the self-detoxification ability of microorganisms to transform As(Ⅴ)to As(Ⅲ)or volatile organic As.This study proposes a strategy of regulating microbes’metabolic activity by biochar to achieve simultaneous removal of coexisting contaminations,which is an important step prior to examining the feasibility of biochar application for enhanced bioremediation.

Identification of long-range transport pathways and potential sources of PM2.5 and PM10 in Beijing from 2014 to 2015

Trajectory clustering, potential source contribution function （PSCF） and concentration-weighted trajectory （CWT） methods were applied to investigate the transport pathways and identify potential sources of PM2.s and PMIo in different seasons from June 2014 to May 2015 in Beijing. The cluster analyses showed that Beijing was affected by trajectories from the south and southeast in summer and autumn. In winter and spring, Beijing was not only affected by the trajectories from the south and southeast, but was also affected by trajectories from the north and northwest. In addition, the analyses of the pressure profile of backward trajectories showed that backward trajectories, which have important influence on Beijing, were mainly distributed above 970 hPa in summer and autumn and below 950 hPa in spring and winter. This indicates that PM2.s and PMIo were strongly affected by the near surface air masses in summer and autumn and by high altitude air masses in winter and spring. Results of PSCF and CV/T analyses showed that the largest potential source areas were identified in spring, followed by winter and autumn, then summer. In addition, potential source regions of PMIo were similar to those of PM2.5. There were a clear seasonal and spatial variation of the potential source areas of Beijing and the airflow in the horizontal and vertical directions. Therefore, more effective regional emission reduction measures in Beijing＇s surrounding provinces should be implemented to reduce emissions of regional sources in different seasons.

Fast and stable K-ion storage enabled by synergistic interlayer and pore-structure engineering

Carbon-based material has been regarded as one of the most promising electrode materials for potassium-ion batteries(PIBs).However,the battery performance based on reported porous carbon electrodes is still unsatisfactory,while the in-depth K-ion storage mechanism remains relatively ambiguous.Herein,we propose a facile“in situ self-template bubbling”method for synthesizing interlayer-tuned hierarchically porous carbon with different metallic ions,which delivers superior K-ion storage performance,especially the high reversible capacity(360.6 mAh·g^(−1)@0.05 A·g^(−1)),excellent rate capability(158.6 mAh·g^(−1)@10.0 A·g^(−1))and ultralong high-rate cycling stability(82.8%capacity retention after 2,000 cycles at 5.0 A·g^(−1)).Theoretical simulation reveals the correlations between interlayer distance and K-ion diffusion kinetics.Experimentally,deliberately designed consecutive cyclic voltammetry(CV)measurements,ex situ Raman tests,galvanostatic intermittent titration technique(GITT)method decipher the origin of the excellent rate performance by disentangling the synergistic effect of interlayer and pore-structure engineering.Considering the facile preparation strategy,superior electrochemical performance and insightful mechanism investigations,this work may deepen the fundamental understandings of carbon-based PIBs and related energy storage devices like sodium-ion batteries,aluminum-ion batteries,electrochemical capacitors,and dual-ion batteries.

仿生学:从生物细胞到电池单元

Biomimetics,a term defined by Schmitt in 1960s,has been accompanying the development of humanity in learning from nature to solve problems over billions of years.The nature-inspired artificial design has driven innovative research across various disciplines,especially materials science,which is the foundation for other biomimetic fields like medicine,robotics,bioelectronics,self-cleaning,catalysts and energy-related devices[1-3].

一种用于高性能聚环氧乙烷基全固态电池的新型珊瑚状石榴石

锂金属电池被认为是最有前景的下一代储能设备之一,但是锂金属电池的安全性问题以及锂枝晶生长问题严重阻碍了它的实用化进程.固态电解质可以有效解决这一安全性问题,表现出能够抑制锂枝晶生长的巨大潜力,并因此受到大家的关注.其中聚环氧乙烷(PEO)基固态电解质由于具有较高的安全性以及出色的柔韧性,被认为是一类非常有应用前景的固态电解质.但是,其固有的半结晶特性以及较差的力学性能导致它们在室温下的离子电导率较低,并且在高温下不能有效地抑制锂枝晶生长.为改善上述问题,本文设计并合成了一种新型的珊瑚状Li_(6.25)Al_(0.25)La_(3)Zr_(2)O_(12)(C-LALZO)活性陶瓷填料来增强PEO聚合物电解质,制备得到的复合固态电解质(PLC)表现出更高的离子电导率和机械强度,保证了锂金属的均匀沉积/剥离.采用PLC的锂对称电池在60℃下循环1500小时不发生短路.组装得到的LiFePO_(4)/PLC/Li全固态电池在60和50℃时均有出色的循环稳定性.这项工作表明,通过调节填料的微观结构(如C-LALZO结构),可以有效地改善复合电解质的电化学性能.