A systematical study on the electrodeposition process of metallic lithium

In this study,commercial copper(Cu)foil and Cu foam are used as the working electrodes to systematically investigate the electrochemical deposition and dissolution processes of metallic lithium(Li)on these electrodes;Li metal deposited on the Cu foil electrode is porous and loose.The surface solid electrolyte interface(SEI)film after dissolution from Li dendrites maintains a dendritic porous structure,resulting in a large volume effect of the electrode during the cycle.The Cu foam electrode provides preferential nucleation and deposition sites near the side surface of the separator;the difference in Li affinity results in a heterogeneous deposition and dendrite growth of metallic Li.

Atomic level deposition to extend Moore’s law and beyond

In the past decades,Moore’s law drives the semiconductor industry to continuously shrink the critical size of transistors down to 7 nm.As transistors further downscaling to smaller sizes,the law reaches its limitation,and the increase of transistors density on the chip decelerates.Up to now,extreme ultraviolet lithography has been used in some key steps,and it is facing alignment precision and high costs for high-volume manufacturing.Meanwhile,the introduction of new materials and 3D complex structures brings serious challenges for top-down methods.Thus,bottom-up schemes are believed to be necessary methods combined with the top-down processes.In this article,atomic level deposition methods are reviewed and categorized to extend Moore’s law and beyond.Firstly,the deposition brings lateral angstrom resolution to the vertical direction as well as top-down etching,such as double patterning,transfer of nanowires,deposition of nanotubes,and so on.Secondly,various template-assisted selective deposition methods including dielectric templates,inhibitors and correction steps have been utilized for the alignment of 3D complex structures.Higher resolution can be achieved by inherently selective deposition,and the underlying selective mechanism is discussed.Finally,the requirements for higher precision and efficiency manufacturing are also discussed,including the equipment,integration processes,scale-up issues,etc.The article reviews low dimensional manufacturing and integration of 3D complex structures for the extension of Moore’s law in semiconductor fields,and emerging fields including but not limited to energy,catalysis,sensor and biomedicals.

Material manufacturing from atomic layer

Atomic scale engineering of materials and interfaces has become increasingly important in material manufacturing.Atomic layer deposition(ALD)is a technology that can offer many unique properties to achieve atomic-scale material manufacturing controllability.Herein,we discuss this ALD technology for its applications,attributes,technology status and challenges.We envision that the ALD technology will continue making significant contributions to various industries and technologies in the coming years.

TiO_(2)/Cu_(2)O heterostructure enabling selective and uniform lithium deposition towards stable lithium metal anodes

Lithium(Li)metal is the ultimate anode choice for next generation high energy density batteries.However,the high nucleation energy barrier and nonuniform electric field distribution,as well as huge volume expansion,lead to the uncontrollable growth of Li dendrites and poor utilization of Li metal,which hinders its practical application.Herein,titanium dioxide/cuprous oxide(TiO_(2)/Cu_(2)O)heterostructure is constructed on the rimous skeleton of Cu mesh,and the heterostructure decorated rimous Cu mesh(H-CM)can act as both current collector and host for dendrite-free Li metal anode.The TiO_(2)/Cu_(2)O heterostructure realizes selective Li nucleation by nano TiO_(2)and then induces fast and uniform Li conduction with the aid of heterostructure interface and nano Cu_(2)O contributing to dendrite-free Li deposition.While the internal and external space of rimous skeletons in H-CM is used to accommodate the deposited Li and buffer its volume change.Therefore,the cycling reversibility of the derived Li metal anode in H-CM is improved to a high Coulombic efficiency of 98.8%for more than 350 cycles at a current density of 1 mA·cm−2,and 1,000 h(equals to 500 cycles)stable repeated Li plating/stripping can be operated in a symmetric cell.Furthermore,full cells with limited Li anode and high loading LiFePO4 cathode present excellent cycling and rate performances.

Selective oxidation of methane and carbon deposition over Fe_2O_3/Ce_(1-x)Zr_xO_2 oxides

A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron microscope（TEM）, and H2-temperature-programmed reduction（H2-TPR） techniques. The gas–solid reactions between these oxides and methane for syngas generation as well as the catalytic performance for selective oxidation of carbon deposition in O2-enriched atmosphere were investigated in detail. The results show that the samples with the presence of Fe2O3show much higher activity for methane oxidation compared with the Ce0.7Zr0.3O2solid solution,while the CeO2-contained samples represent higher CO selectively in methane oxidation than the Fe2O3/Al2O3sample. This suggests that the iron species should be the active sites for methane activation, and the cerium oxides provide the oxygen source for the selective oxidation of the activated methane to syngas during the reaction between methane and Fe2O3/Ce0.7Zr0.3O2. For the oxidation process of the carbon deposition, the CeO2-containing samples show much higher CO selectivity than the Fe2O3/Al2O3sample, which indicates that the cerium species should play a very important role in catalyzing the carbon selective oxidation to CO. The presence of the Ce–Zr–O solid solution could induce the growth direction of the carbonfilament, resulting in a loose contact between the carbon filament and the catalyst. This results in abundant exposed active sites for catalyzing carbon oxidation, strongly improving the oxidation rate of the carbon deposition over this sample. In addition, the Fe2O3/Ce0.7Zr0.3O2also represents much higher selectivity（ca. 97 %） for the conversion of carbon to CO than the Fe2O3/CeO2sample, which can be attributed to the higher concentration of reduced cerium sites on this sample. The increase of the Zr content in the Fe2O3/Ce1-xZrxO2samples could improve the reactivity of the materials for methane oxidation, but it also reduces the selectivity for CO formation.