We report subnanometer modification enabled by an ultrafine helium ion beam. By adjusting ion dose and the beam profile, structural defects were controllably introduced in a few-layer molybdenum disulfide (MoS2) sample and its stoichiometry was modified by preferential sputtering of sulfur at a few-nanometer scale. Localized tuning of the resistivity of MoS2 was demonstrated and semiconducting, metallic-like, or insulating material was obtained by irradiation with different doses of He(+). Amorphous MoSx with metallic behavior has been demonstrated for the first time. Fabrication of MoS2 nanostructures with 7 nm dimensions and pristine crystal structure was also achieved. The damage at the edges of these nanostructures was typically confined to within 1 nm. Nanoribbons with widths as small as 1 nm were reproducibly fabricated. This nanoscale modification technique is a generalized approach that can be applied to various two-dimensional (2D) materials to produce a new range of 2D metamaterials.

Owing to their theoretical energy density of 2600 Wh kg , lithium-sulfur batteries represent a promising future energy storage device to power electric vehicles. However, the practical applications of lithium-sulfur batteries suffer from poor cycle life and low Coulombic efficiency, which is attributed, in part, to the polysulfide shuttle and Li dendrite formation. Suppressing Li dendrite growth, blocking the unfavorable reaction between soluble polysulfides and Li, and improving the safety of Li-S batteries have become very important for the development of high-performance lithium sulfur batteries. A comprehensive review of various strategies is presented for enhancing the stability of the anode of lithium sulfur batteries, including inserting an interlayer, modifying the separator and electrolytes, employing artificial protection layers, and alternative anodes to replace the Li metal anode.

reaction of 16Li + S 8 → 8Li 2 S. [2] However, the dissolution of intermediate products formed during the charge/discharge process, the so-called shuttle effect, causes severe capacity decay and lower coulombic efficiency of the batteries. [3,4] A variety of strategies have been tried to solve the above-mentioned issues, including fabrication of carbon-sulfur composites, [5] surface modification of conducting polymers, [6,7] and the modifications of electrolyte. [8] Though these approaches lead to improved electrical conductivity, cyclability, and capacity, there are still some challenging issues such as ≈20% polysulfide (PS) leaking into electrolyte, fast capacity decay in subsequent cycles, and a low lithium ion conductivity in new electrolytes and their stability. More recently, introducing an interlayer between the sulfur cathode and separator, such as a carbon paper, [9] carbonized eggshell membrane, [10] carbon nanotube paper, [11] and an acetylene black mesh, [12] has been developed for the absorption of soluble PS and reuse of the absorbed active material. This strategy significantly enhances both rate performance and cycling life of batteries. However, the complexity of the interlayer preparation, weak interaction between the interlayer and polar PS anions, and the unacceptable thickness and heavy mass of the interlayer affect the Li-S cell's performance significantly. Therefore, developing a new lightweight interlayer that can not only increase the electric conductivity but can also alleviate PS transport from anode to cathode is a challenge.Boron nitride nanosheet (BNNS), isoelectronic with graphene, has been proven to promise a wide range of applications such as field nanoemitters, nanoelectronics, and composite reinforcement due to its many remarkable properties including extremely high resistance to oxidation and good chemical inertness, electrical insulating, high surface area, high thermal conductivity, and stability. [13][14][15][16][17][18][19] In addition, innovative adsorptive applications in hydrogen storage, and the adsorption of dyes, proteins, organic solvents, metal ions, and oils have been explored for BNNSs due to the strong electrostatic attraction and noncovalent interaction. More recently, we have developed a functionalized BNNS (FBN) with positively charged amino groups by a solid-state ball milling method. [20] The positively charged amino groups on the BNNSs make them attractive for solving certain problems in Li-S battery. Because PS anions Lithium-sulfur (Li-S) batteries have a much higher energy density than Li ion batteries and thus are considered as next generation batteries for electric vehicle applications. However, the problem of rapid capacity fading due to the shuttling of soluble polysulfides between electrodes remains the main obstacle for practical applications. Here, a thin and selective interlayer structure has been designed and produced to decrease the charge transfer resistance and mitigate the shuttling problem, simply by coating the surface of cathode with a thi...

A molten lithium infusion strategy has been proposed to prepare stable Li-metal anodes to overcome the serious issues associated with dendrite formation and infinite volume change during cycling of lithium-metal batteries. Stable host materials with superior wettability of molten Li are the prerequisite. Here, it is demonstrated that a series of strong oxidizing metal oxides, including MnO 2 , Co 3 O 4 , and SnO 2 , show superior lithiophilicity due to their high chemical reactivity with Li. Composite lithium-metal anodes fabricated via melt infusion of lithium into graphene foams decorated by these metal oxide nanoflake arrays successfully control the formation and growth of Li dendrites and alleviate volume change during cycling. A resulting Li-Mn/graphene composite anode demonstrates a super-long and stable lifetime for repeated Li plating/stripping of 800 cycles at 1 mA cm −2 without voltage fluctuation, which is eight times longer than the normal lifespan of a bare Li foil under the same conditions. Furthermore, excellent rate capability and cyclability are realized in full-cell batteries with Li-Mn/graphene composite anodes and LiCoO 2 cathodes. These results show a major advancement in developing a stable Li anode for lithium-metal batteries.

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The rapid development of flexible electronics has triggered extensive efforts to explore matching flexible energy-storage devices as power sources. Flexible lithium-ion batteries (LIBs) have been demonstrated as the current most attractive and versatile energy storage devices for flexible electronics. A series of designs and constructions for flexible LIBs have been investigated in recent years. Particularly, significant progress has been achieved in finding high performance electrolyte and electrode materials, new structural designs as well as suitable fabrication methods for flexible LIBs. In this review, the recent advances in the exploration of flexible lithium-ion batteries are summarized and discussed, with special focus on the selectivity of flexible electrode/electrolyte materials, cell structure design, and full cell assembly process. Perspectives for the future development of flexible LIBs are also discussed.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

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Poor cyclability and safety concerns caused by the uncontrollable dendrite growth and large interfacial resistance severely restrict the practical applications of metal batteries. Herein, a facile, universal strategy to fabricate ceramic and glass phase compatible, and self‐healing metal anodes is proposed. Various amalgam‐metal anodes (Li, Na, Zn, Al, and Mg) show a long cycle life in symmetric cells. It has been found that liquid Li amalgam shows a complete wetting with the surface of lanthanum lithium titanate electrolyte and a glass‐phase solid‐state electrolyte. The interfacial compatibility between the lithium metal anode and solid‐state electrolyte is dramatically improved by using an in situ regenerated amalgam interface with high electron/ion dual‐conductivity, obviously decreasing the anode/electrolyte interfacial impedance. The lithium‐amalgam interface between the metal anode and electrolyte undergoes a reversible isothermal phase transition between solid and liquid during the cycling process at room temperature, resulting in a self‐healing surface of metal anodes.