Lithium (Li) metal anode (LMA) is one of the most promising anodes for high energy density batteries. However, its practical application is impeded by notorious dendrite growth and huge volume expansion. Although the three-dimensional (3D) host can enhance the cycling stability of LMA, further improvements are still necessary to address the key factors limiting Li plating/stripping behavior. Herein, porous copper (Cu) foam (CF) is thermally infiltrated with molten Li-rich Li-zinc (Li-Zn) binary alloy (CFLZ) with variable Li/Zn atomic ratio. In this process, the LiZn intermetallic compound phase self-assembles into a network of mixed electron/ion conductors that are distributed within the metallic Li phase matrix and this network acts as a sublevel skeleton architecture in the pores of CF, providing a more efficient and structured framework for the material. The as-prepared CFLZ composite anodes are systematically investigated to emphasize the roles of the tunable lithiophilicity and hierarchical structure of the frameworks. Meanwhile, a thin layer of Cu-Zn alloy with strong lithiophilicity covers the CF scaffold itself. The CFLZ with high Zn content facilitates uniform Li nucleation and deposition, thereby effectively suppressing Li dendrite growth and volume fluctuation. Consequently, the hierarchical and lithiophilic framework shows low Li nucleation overpotential and highly stable Coulombic efficiency (CE) for 200 cycles in conventional carbonate based electrolyte. The full cell coupled with LiFePO4 (LFP) cathode demonstrates high cycle stability and rate performance. This work provides valuable insights into the design of advanced dendrite-free 3D LMA toward practical application.

Integrating metallic lithium (Li) with a three-dimensional (3D) host is a popular strategy for long-life Li composite anodes, where the structure and physicochemical nature of the framework are critical for the electrochemical performance. Herein, Li-rich dual-phase barium (Ba)-based alloy composed of BaLi4 intermetallic compounds and Li metal phases is thermally incorporated into commercial carbon cloth sheets to develop Li-Ba alloy composite (LBAC) anodes featuring a porous array of BaLi4 microchannels as the built-in 3D skeleton. Doping of metallic Ba can greatly lower the surface tension of liquid Li and improve the wettability of the molten Li-Ba alloy toward the carbon cloth substrate. Moreover, LBAC benefits from the superior lithiophilicity and the porous architecture of BaLi4 skeleton nested in a conductive carbon fiber matrix, leading to stable cycling performance by confining Li stripping/plating in microchannels network of BaLi4 alloy framework and dissipating high current densities. As a result, the LBAC symmetrical cells can run stably for 1,000 h under 1 mA cm-2 and 1 mA h cm-2, and the capacity retention can retain 93.3% after 300 cycles in the full cell with areal capacity of 2.45 mA h cm-2. This work offers a smart designing strategy of 3D Li alloy composite anodes by introducing porous and lithiophilic alloy scaffold as sub-framework of the carbon hosting anode, promising the prospect of Li metal batteries for future applications.

Lithium (Li)-rich ternary alloy, comprising a multi-alloy phase as the built-in three-dimensional (3D) framework and a Li metal phase as a reversible Li reservoir, is a promising high-energy-density anode for rechargeable Li metal batteries. The introduction of metal/metalloid components to the alloy can effectively regulate Li deposition and maintain the dimensional integrity of the Li anode. Herein, the lithium-copper-zinc (Li-Cu-Zn) ternary alloy, as a new type of alloy anode, is synthesized via a facile thermal melting method. The fully delithiated 3D scaffold comprised two Cu-Zn alloy phases named CuZn and CuZn5. These alloy phases exhibit higher lithiophilicity and structural stability than Li-Zn and Li-Cu alloys. Moreover, the CuZn phase is electrochemically inert, ensuring the geometric stability of the anode, while the CuZn5 phase can readily undergo alloying reaction with Li to form the LiZn phase, thereby facilitating uniform Li nucleation and deposition. The hybridized multiphase alloy structure and specific energy storage mechanism of the Cu-Zn based alloy scaffold in the ternary alloy anode facilitate dendrite-free Li deposition and prolonged cycle lifetime. The Li metal full battery based on lithium iron phosphate (LiFePO4) cathode exhibits high cycling stability with high-capacity retention of 95.4% after 1000 cycles at 1C.

The cost-effective mass production of high-performance ultrathin lithium metal anodes is a bottleneck hindering the commercialization of high-energy-density Li metal batteries. Compared to complex and expensive conven-tional fabrication techniques including sputtering, electrodeposition, and pressure-rolling, the wet coating of molten Li on a Cu sheet is a very promising strategy. Unfortunately, the wettability of molten Li on the Cu surface is very poor, creating difficulty in achieving a uniform Li film. Herein, a facile and efficient approach to the application of melt coatings is realized through the alloying reaction between molten Li and the heated Cu surface. An ultrathin and uniform Li film with a thickness of 5 -50 mu m is prepared via roll-to-roll fabrication. Remarkably, a three-dimensional LiCux solid-solution alloy skeleton is formed inside the ultrathin Li, achieving the dual purpose of lithiophilicity and high performance. The full cell with the N/P ratio of 3.2, consisting of a LiFePO4 cathode with an areal capacity of 1.58 mAh center dot cm- 2 and a 25 mu m thick LiCux/Li composite anode, exhibited stable cycling for more than 480 cycles at 1 C. This work provides a potential solution for the industrial production of high-performance and cost-effective ultrathin Li metal anodes.

Lithium (Li) metal composite with three-dimensional (3D) skeleton is regarded as the promising anode material for next generation rechargeable high energy batteries. Currently, most of the commercial cathodes are compounds rich of Li elements. In the initial operation of the as-assembled full cell, Li atoms are released from the cathode and directly deposited on the anode surface. The absence of the storage space in the conventional Li composite anode makes Li growth in an uncontrolled way and serious volume fluctuation of the electrode. Herein, LiF headspace affixed Li composite anode is prepared for the first time via a facile one-step thermal fusion method. The storage space constructed by LiF particles is formed on the top surface of 3D Li-LiZn-LiF (LZLF) composite anode, which can accommodate Li deposition from the cathode maintaining structural stability of the anode. Additionally, the LiF particles array on the surface can benefit for fast Li+ diffusion, suppressing Li dendrites growth and inducing uniform Li deposition. In a consequence, the LiF headspace affixed LZLF composite anode shows significantly improved electrochemical performance, i.e., more than 1000 h in symmetrical cell at 1 mA cm(-2) and 1 mAh cm(-2), or capacity retention of 88.9% after 800 cycles for the full cell at 1C with 2.45 mAh cm(-2) in carbonate ester-based electrolyte.

The exploration of cost-effective hydrogen evolution reaction (HER) electrocatalysts through water splitting is important for developing clean energy technology and devices. The application of CoS2 in HER has been drawing more and more attention due to its low cost and relatively satisfactory HER catalytic performance. And CoS2 was found to exhibit excellent HER catalytic performance after appropriate doping according to other experimental investigations. However, the theoretical simulation and the intrinsic catalytic mechanism of CoS2 remains insufficiently investigated. Therefore, in this study, density functional theory is used to investigate the HER catalytic activity of CoS2 doped with a heteroatom. The results show that Pt-, N- and O-doped CoS2 demonstrates smaller Gibbs free energies close to that of Pt, compared with the original CoS2 and CoS2 doped with other atoms. Furthermore, HER catalytic performance of CoS2 can be improved by tuning d-band centers of H adsorption sites. This study provides an effective method to achieve modified CoS2 for high-performance HER and to investigate other transition metal sulfides as HER electrode.

With the increased demand for high-rate performance Li-ion batteries, it is necessary to find available methods to improve the rate properties of SnO2 electrodes. It is noteworthy that doping was considered to be a feasible means. The electronic structures and diffusion energy barriers of Ni-doped and Ni-N co-doped SnO2 were calculated based on density functional theory. The results estimated that the energy gaps of Ni-doped and Ni-N co-doped SnO2 are 1.07 eV and 0.94 eV, which both are smaller than the value of 2.08 eV of SnO2. These exhibit that the conduction properties of SnO2 can be enhanced by doping with the Ni or Ni-N atoms. Moreover, the diffusion properties of Li can also be improved by doping with Ni-N atoms due to the diffusion energy barrier of Li from the B to C point for Ni-N co-doped SnO2 being 0.12 eV smaller than the value of 0.24 eV for the pristine SnO2. Meanwhile, the diffusion energy barriers of Li along other pathways for Ni-N co-doped SnO2 are almost the same as 0.24 eV for SnO2. These results show that both the electronic and ionic conductivity of SnO2 can be enhanced by Ni-N co-doping, which provides a theoretical explanation to promote the rate properties of SnO2 by Ni-N co-doping as anode materials for Li-ion batteries.

Uneven deposition and serious volume change restrict the commercial application of Li metal anode. Sn based alloy is pursued as the advanced anode via an alloying/dealloying mechanism while considering its resource abundance, low price, and high specific capacity. Herein, a three-dimensional (3D) Li22Sn5 alloy skeleton is integrated with Li metal phase via phase-segregation process by a facial melting method, in which Li-rich dual-phase Li-Sn alloy named SnLi90 is produced. The free Li phase accounts for a huge proportion of the electrode weight and acts as the active material offering ultra-high specific capacity of 3087 mAh g(-1). Alternatively, the unique interconnected rod-like Li22Sn5 network serves as electrochemical "inert " framework due to its much higher redox potential. The favorable Li affinity of the Li22Sn5 skeleton contributes to conformal Li deposition. Consequently, the SnLi90 anode can cycle stably for 1500 h in ester electrolyte at 1 mA cm(-2) and 1 mAh cm(-2), almost three times longer than that of the bare Li anode. (c) 2021 Elsevier Ltd. All rights reserved.

The hostless nature of a lithium metal anode leads to dendrite growth and dimension change, which severely restrict the application of rechargeable lithium metal cells. Optimization design for the ...

Due to the problem that the existing Doppler frequency rate estimation method is limited by the estimation accuracy, a novel estimation method of Doppler frequency rate is proposed. The present method searches the frequency rate according to the characteristic of the chirp signal in the FrFT domain. Firstly, dechirp is performed on several strong scattering points extracted from the data domain after pulse compression, and a frequency domain focused image is obtained after FFT. Then the maximum point of each distance unit is extracted. The energy of the maximum point is selected by using the window processing. After that, IFFT is performed and the dechirp conjugate reference function is multiplied by using the selected points. FrFT is performed according to the preset orders. The entropy is used to evaluate whether the order of FRFT is optimal or not. The Doppler frequency rate is calculated by using the optimal order. The simulation and real data are processed and analyzed. The present method can estimate the Doppler frequency rate accurately. A well-focused SAR image is obtained after azimuth matching filtering.

Lithium metal is an ideal anode material for lithium battery thanks to its ultra-high specific capacity and lowest redox potential. However, uncontrollable growth of lithium dendrites hinders its application due to local aggregation of lithium ions and anisotropic growth of lithium metal driven by uneven electric field distribution. Here a strategy is proposed to address this issue via utilizing porous equipotential body decorated with heterogeneous nucleation sites as advanced three-dimensional current collector. The conductive network of carbon nanofibers is recognized as a porous equipotential body, where the interior electric filed is zero due to the well-defined electric field shielding effect. In addition, copper nanoparticles as heterogeneous nucleation sites are uniformly anchored on carbon nanofibers, which guide lithium deposition evenly. As a result, lower impedance and higher Coulombic efficiency (-97%) are achieved in modified lithium-copper cell. In particular, the cycling lifetime of modified symmetric lithium-lithium cell is expanded up to 500 cycles at extremely large current density of 50 mA cm(-2). (C) 2019 Elsevier Ltd. All rights reserved.

Though lithium (Li) metal is an ideal anode material for next-generation rechargeable batteries, its application has been seriously limited by security and cyclability issues as the result of uncontrollable Li dendrite growth. To solve this problem, this paper proposes a method to suppress Li dendrite growth using melamine-derived 3D porous carbon foam decorated with graphite intercalation compounds of Li (GICs-Li) as a Li host. GICs-Li, with excellent lithiophilicity, ensures uniform Li deposition, while the 3D porous carbon foam, with ultrahigh porosity and enlarged surface area, provides pathway for Li+ transport, accommodates Li deposition as well as reduces practical current density. Thus, dendrite-free morphology of composite Li anode is realized without additional heterogeneous lithiophilic particles. In symmetric cell configuration, the composite Li anode performs stably for 500 cycles at 10 mAcm(-2). In full cell configuration with Li4Ti5O12 (LTO), it exhibits a large capacity retention rate (similar to 91%) after 700 cycles at 1.0C.