Manipulation of the LiZn Alloy Process toward High-Efficiency Lithium Metal Anodes.

Synthesis of alloy-type materials (X) is one of the most effective approaches to limit lithium dendrites in Li metal anode (LMA) because of their satisfactory lithiophilicity and easy electrochemical reaction with lithium. However, current investigations have only focused on the influence of the resulting alloyed products (LiX) on the properties of LMA, but the alloying reaction process between Li+ and X has been mostly ignored. Herein, by masterly taking advantage of the alloying reaction process, a novel approach is developed to more effectively inhibit lithium dendrites than the conventional strategy that just considers the utilization of alloyed products LiX. A three-dimensional substrate material loaded with metallic Zn on the surface of Cu foam is synthesized by a simple electrodeposition process. During Li plating/stripping, both alloy reaction processes between Li+ and Zn and LiZn product are involved, which makes the disordered Li+ flux near the substrate first react with Zn metal and then results in an even Li+ concentration for more uniform Li nucleation and growth. The full cell (Li-Cu@Zn-15//LFP) exhibits the reversible capacity of 122.5 mAh g-1, and a high capacity retention of 95% is achieved after 180 cycles. This work proposes a valuable concept for the development of alloy-type materials in energy storage devices.

Carbonized Polymer Dots with Controllable N, O Functional Groups as Electrolyte Additives to Achieve Stable Li Metal Batteries.

Electrolyte additive is an effective strategy to inhibit the uncontrolled growth of Li dendrites for lithium metal batteries (LMBs). However, most of the additives are complex synthesis and prone to decompose in cycling. Herein, in order to guide the homogeneous deposition of Li+ , carbonized polymer dots (CPDs) as electrolyte additives are successfully designed and synthesized by microwave (M-CPDs) and hydrothermal (H-CPDs) approaches. The controllable functional groups containing N or O (especially pyridinic-N, pyrrolic-N, and carboxyl group) enable CPDs to keep stable in electrolytes for at least 3 months. Meanwhile, the clusters formed between CPDs and Li+ through electrostatic interaction effectively guide the uniform Li dispersion and limit the "tip effect" and dendrite formation. Moreover, as lithiophilic groups increase, the strong electrostatic interference for the solvation effect of Li+ in the electrolyte is formed, which induces faster Li+ diffusion/transfer. As expected, H-CPDs achieve the ultra-even Li+ transfer. The corresponding Li//LiFePO4 full cell delivers a high capacity retention rate of 93.8% after 200 cycles, which is much higher than that of the cells without additives (61.2%) and with M-CPDs (83.7%) as additives. The strategy in this work provides a theoretical direction for CPDs as electrolyte additives used in energy storage devices.

Robust Electrodes for Flexible Energy Storage Devices Based on Bimetallic Encapsulated Core-Multishell Structures.

Developing flexible electrodes with high active materials loading and excellent mechanical stability is of importance to flexible electronics, yet remains challenging. Herein, robust flexible electrodes with an encapsulated core-multishell structure are developed via a spraying-hydrothermal process. The multilayer electrode possesses an architecture of substrate/reduced graphene oxide (rGO)/bimetallic complex/rGO/bimetallic complex/rGO from the inside to the outside, where the cellulosic fibers serve as the substrate, namely, the core; and the multiple layers of rGO and bimetallic complex, are used as active materials, namely, the shells. The inner two rGO interlayers function as the cement that chemically bind to two adjacent layers, while the two outer rGO layers encapsulate the inside structure effectively protecting the electrode from materials detachment or electrolyte corrosion. The electrodes with a unique core-multishell structure exhibit excellent cycle stability and exceptional temperature tolerance (-25 to 40 °C) for lithium and sodium storage. A combination of experimental and theoretical investigations are carried out to gain insights into the synergetic effects of cobalt-molybdenum-sulfide (CMS) materials (the bimetallic complex), which will provide guidance for future exploration of bimetallic sulfides. This strategy is further demonstrated in other substrates, showing general applicability and great potential in the development of flexible energy storage devices.

[Searching QSO candidates and calculating their redshfit from a flood of spectra].

In the present paper the author offers a method to search the QSO candidates and calculate their redshfit using their broad emission lines which are the most important character of quasars. It is hard to identify the lines in the quasar's spectra due to their redshifts distributing on a broad range. Spectra contain two components. One is continuum and the other is lines. The author uses a method of LFPS (low frequency points set) to build the continuum and detect the obvious emission lines, a method that can avoid the broad emission lines as a part of the continuum. The redshift can be calculated by comparing the extracted lines with the line table. The classification can be done with both emission lines and the redshift. For a better accurate rate to recognize the lines, this paper provides a method to estimate the level of the local noise. The method this paper used is independent of the flux calibration of the spectra. It can work for the spectra of the present LAMOST.