Facile construction of a multilayered interface for a durable lithium‐rich cathode

Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.

Composite solid electrolyte of Na3PS4-PEO for all-solid-state SnS2/Na batteries with excellent interfacial compatibility between electrolyte and Na metal

High ionic conductivity and superior interfacial stability of solid electrolytes at the electrodes are crucial factors for high-performance all-solid-state sodium batteries. Herein, a composite solid electrolyte Na3PS4-polyethylene oxide is synthesized by the solution-phase reaction method with an improved ionic conductivity up to 9.4 × 10-5 S/cm at room temperature. Moreover, polyethylene oxide polymer layer is wrapped homogeneously on the surface of Na3PS4 particles, which could effectively avoid the direct contact between Na3PS4 electrolyte and sodium metal, thus alleviate their side reactions. We demonstrate that all-solid-state battery SnS2/Na with the composite solid electrolyte Na3PS4-polyethylene oxide delivers an enhanced electrochemical performance with 230 m Ah/g after 40 cycles.

Potassium pre-inserted K1.04Mn8O16 as cathode materials for aqueous Li-ion and Na-ion hybrid capacitors

For the applications of aqueous Li-ion hybrid capacitors and Na-ion hybrid capacitors,potassium ions are pre-inserted into MnO2 tunnel structure,the as-prepared K1.04Mn8 O16 materials consist of nanoparticles and nanorods were prepared by facile high-temperature solid-state reaction.The as-prepared materials were well studied and they show outstanding electrochemical behavior.We assembled hybrid supercapacitors with commercial activated carbon(YEC-8 A)as anode and K1.04Mn8 O16 as cathode.It shows high energy and power densities.Li-ion capacitors reach a high energy density of 127.61 Wh kg-1 at the power density of 99.86 W kg-1 and Na-ion capacitor obtains 170.96 Wh kg-1 at 133.79 W kg-1.In addition,the hybrid supercapacitors demonstrate excellent cycling performance which maintain 97%capacitance retention for Li-ion capacitor and 85%for Na-ion capacitor after 10,000 cycles.

Guest ions pre-intercalation strategy of manganese-oxides for supercapacitor and battery applications

Optimization of intrinsic structure of electrode materials plays decisive roles in promoting the development of energy storage systems to meet the fast-growing requirements in the market.Interlayer engineering has been proved to be an effective way to obtain adequate active sites,preferable ion diffusion channels and stable structure,thus enhance the performance of batteries.An in-depth understanding of the correlation among synthesis,structure and performance will significantly promote the development of excellent materials and energy storage devices.Therefore,in this review,recent advances in regards to cation preintercalation engineering in Mn-based electrode materials for rechargeable metal ion batteries are systematically summarized.Preintercalated guest cations can expand interlayer space to promote ion diffusion kinetics,serve as pillars to stabilize structure,control composition and valence to switch electrochemical behavior,thus improve the overall performance of secondary batteries.Moreover,the existing challenges and perspectives are provided for the interlayer engineering and its promotion to battery industry.

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.

Boosting fast interfacial Li^(+)transport in solid-state Li metal batteries via ultrathin Al buffer layer

Na superionic conductor(NASICON)-type Li_(1.5)Al_(0.5)Ge_(0.5)P_(3)O_(12)(LAGP)solid state electrolytes(SSEs)have attracted significant interests thanks to the prominent ionic conductivity(>10^(–4)S·cm^(–1))at room temperature and superb stability in air.Unfortunately,its application has been hindered by the lithium dendrites and the intrinsic interfacial instability of LAGP towards metallic Li,etc.Herein,by magnetron sputtering(MS),an ultrathin Al film is deposited on the surface of the LAGP pellet(Al-LAGP).By in-situ alloying reaction,the spontaneously formed LiAl buffer layer inhibits the side reaction between LAGP SSEs and Li metal,induces the uniform distribution of interfacial electric field as well.Density functional theory(DFT)calculations demonstrate that the LiAl alloy surface promotes the diffusion of lithium atoms due to the lower energy barrier,thereby inhibiting the formation of lithium dendrites.Consequently,the Li/Al-LAGP-Al/Li symmetric cells show a low resistance of 210Ωand a durable lifespan over 1,200 h at a high current density of 0.1 mA·cm^(-2).Assembled all solid state lithium metal batteries(ASSLMBs)with LiFePO_(4)(LFP)cathode significantly improve cycle stability and rate performance,proving a promising stabilization strategy towards the NASIOCN type electrolyte/anode interface in solid state Li metal batteries.

Dissolution and recrystallization of perovskite induced by N-methyl-2-pyrrolidone in a closed steam annealing method

High quality perovskite films with large columnar grains are greatly desired for efficient perovskite solar cells. Here, low volatility N-methyl-2-pyrrolidone(NMP) was added in MAI/IPA solution in a two-step spin-coating method, which promoted the conversion of lead iodide to perovskite. The perovskite films were annealed by a closed-steam annealing method to prolong the recrystallization process of perovskite films assisted by the residual NMP. It leaded to high quality CH_3NH_3PbI_3 perovskite films with large columnar grains due to its enhancement of the Oswald ripening. The large grain perovskite film leaded to efficient carrier transformation and injection, and low recombination. The photovoltaic performance of the perovskite solar cells was improved significantly.

Ag doped urchin-like α-MnO2 toward efficient and bifunctional electrocatalysts for Li-02 batteries

Rechargeable Li-O2 batteries (LOBs) have been receiving intensive attention because of their ultra-high theoretical energy densityclose to the gasoline. Herein, Ag modified urchin-like α-MnO2 (Ag-MnO2) material with hierarchical porous structure is obtained bya facile one-step hydrothermal method. Ag-MnO2 possesses thick nanowires and presents hierarchical porous structure of mesoporesand macropores. The unique structure can expose more active sites, and provide continuous pathways for O2 and discharge productsas well. The doping of Ag leads to the change of electronic distribution in α-MnO2 (i.e., more oxygen vacancies), which playimportant roles in improving their intrinsic catalytic activity and conductivity. As a result, LOBs with Ag-MnO2 catalysts exhibit loweroverpotential, higher discharge specific capacity and much better cycle stability compared to pure a-MnO2. LOBs with Ag-MnO2catalysts exhibit a superior discharge specific capacity of 13,131 mA·h·g^-1 at a current density of 200 mA·h·g^-1, a good cycle stabilityof 500 cycles at the capacity of 500 mA·h·g^-1. When current density is increased to 400 mA·h·g^-1, LOBs still retain a long lifespan of170 cycles at a limited capacity of 1,000 mA·h·g^-1.

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.

Controlled Nanocutting of Graphene

Rapid progress in graphene-based applications is calling for new processing techniques for creating graphene components with different shapes,sizes,and edge structures.Here we report a controlled cutting process for graphene sheets,using nickel nanoparticles as a knife that cuts with nanoscale precision.The cutting proceeds via catalytic hydrogenation of the graphene lattice,and can generate graphene pieces with specifi c zigzag or armchair edges.The size of the nanoparticle dictates the edge structure that is produced during the cutting.The cutting occurs along straight lines and along symmetry lines,defined by angles of 60ºor 120º,and is defl ected at free edges or defects,allowing practical control of graphene nano-engineering.

嵌入多原子掺杂碳纳米阵列中的磷掺杂双金属硫化物应用于柔性全固态超级电容器

柔性超级电容器具有超长使用寿命、可折叠、可穿戴等特点,已成为研究热点.然而,较低的能量密度限制了其更广泛的应用.本文采用简单的方法合成了一种嵌入多原子(氮,硫和磷原子)掺杂碳壳的磷掺杂双金属硫化物(P-ZCS/HC)作为高性能柔性电极.在退火过程中,前驱体的三维形貌保持不变,同时纳米片表面有凸起的纳米球形颗粒形成,这大大增加了电极的比表面积.优化后的P-ZCS/HC电极在1 A g^(-1)时具有1080 C g^(-1)高比电容值,且循环稳定性出色.这些优异的性能主要是由于该电极材料可发生丰富的氧化还原反应,磷化后增强的导电性,以及磷掺杂金属硫化物和多原子掺杂碳壳之间的协同效应.密度泛函理论模拟表明,磷掺杂处理具有提高电导率、改善反应动力学和促进OH-吸附的积极作用.组装的全固态柔性混合超级电容器最高能量密度可达62.9 W h kg^(-1),功率密度可达16 k W kg^(-1),循环10,000次后仍能保持初始容量的92.0%.这一完整和系统的研究为将来设计具有复杂成分和优异结构的柔性电极提供了一种新的思路.

On the Growth Mechanism of Nickel and Cobalt Nanowires and Comparison of Their Magnetic Properties

Magnetic nanowires(NWs)are ideal materials for the fabrication of various multifunctional nanostructures which can be manipulated by an external magnetic fi eld.Highly crystalline and textured nanowires of nickel(Ni NWs)and cobalt(Co NWs)with high aspect ratio(~330)and high coercivity have been synthesized by electrodeposition using nickel sulphate hexahydrate(NiSO_(4)·6H_(2)O)and cobalt sulphate heptahydrate(CoSO_(4)·7H_(2)O)respectively on nanoporous alumina membranes.They exhibit a preferential growth along〈110〉.A general mobility assisted growth mechanism for the formation of Ni and Co NWs is proposed.The role of the hydration layer on the resulting one-dimensional geometry in the case of potentiostatic electrodeposition is verified.A very high interwire interaction resulting from magnetostatic dipolar interactions between the nanowires is observed.An unusual low-temperature magnetisation switching for fi eld parallel to the wire axis is evident from the peculiar high fi eld M(T)curve.

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.

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.

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.

High-damping and conducting epoxy nanocomposite using both zinc oxide particles and carbon nanofibers

In this study,high-damping and conducting epoxy nanocomposites were developed with carbon nanofibers as conducting materials,and zinc oxide particles as piezoelectric materials.The mechanical and electrical properties,electrical impedance,and loss factors were investigated by uniaxial tensile tests,voltage measurement,impedance measurement,and 3-point bending tests.Two percolation thresholds were found:the percolation threshold of resistivity due to the carbon nanofibers forming conductive networks in the matrix;and the impedance threshold due to the zinc oxide particles acting like electric barriers.A poling treatment of the high-damping and conducting epoxy nanocomposite was considered,and we found that poling treatment helped to make the networks more conductive and to generate voltage from ZnO particles.A high-damping and conducting epoxy nanocomposite with 3 wt%CNF and 10 wt%ZnO exhibited higher loss factor than those of others tested.