The development of high‐energy density batteries is critical to the decarbonization of the transportation and power generation sectors. For any given lithium‐containing cathode system, the anode‐free ...full cell configuration, which eliminates excess lithium and pairs the fully lithiated cathode with a bare current collector, can deliver the maximum possible energy density. The absence of free lithium metal during cell assembly confers significant practical advantages as well. It is also the ideal framework for developing a thorough understanding of lithium deposition in conjunction with various cathode systems. However, the poor efficiencies of lithium plating and stripping lead to rapid lithium inventory loss and poor cycle life. In the last few years, multiple studies have demonstrated the application of advanced electrolytes, modified current collectors, and optimized formation and cycling parameters to stabilize lithium deposition and improve cycle life (80% capacity retention) to 100 cycles and beyond. This review provides an overview of the various strategies toward sustaining lithium inventory in anode‐free full cells and summarizes the work undertaken in this nascent field. It is expected that further improvement upon these strategies and a combinatorial approach can enable cycle lives far in excess of what has been achieved so far.
The various considerations for obtaining a detailed understanding of the electrochemical performance of anode‐free full cells are elucidated. The work in this field on improving cyclability, including optimized electrolyte formulations, modified current collector substrates, and favorable cycling protocols, is comprehensively reviewed. Finally, an outlook on this nascent field is provided.
The Panchromatic Hubble Andromeda Treasury (PHAT) survey is an ongoing Hubble Space Telescope (HST) multi-cycle program to obtain high spatial resolution imaging of one-third of the M31 disk at ...ultraviolet through near-infrared wavelengths. In this paper, we present the first installment of the PHAT stellar cluster catalog. When completed, the PHAT cluster catalog will be among the largest and most comprehensive surveys of resolved star clusters in any galaxy. The exquisite spatial resolution achieved with HST has allowed us to identify hundreds of new clusters that were previously inaccessible with existing ground-based surveys. We identify 601 clusters in the Year 1 sample, representing more than a factor of four increase over previous catalogs within the current survey area (390 arcmin super(2)). This work presents results derived from the first ~25% of the survey data; we estimate that the final sample will include ~2500 clusters. For the Year 1 objects, we present a catalog with positions, radii, and six-band integrated photometry. Along with a general characterization of the cluster luminosities and colors, we discuss the cluster luminosity function, the cluster size distributions, and highlight a number of individually interesting clusters found in the Year 1 search.
Stabilizing the metallic lithium anode is the major roadblock to realizing long cycle life lithium‐sulfur (Li–S) batteries with high energy density. The chemistry of the dynamically evolving ...solid‐electrolyte interphase layer on the lithium surface is critical to achieving reversible plating and stripping of lithium. Herein, electrolyte formulations are carefully varied and employed to modulate the composition, and thereby, the properties of the lithium‐electrolyte interface. The impact of these changes in the interfacial chemistry on the dynamics of lithium deposition is evaluated by tracking cyclability in an anode‐free full cell configuration. Critical insights are revealed on the role of different components of the electrolyte and their interplay, including various functional groups in the electrolyte salt, oxidizing effect of lithium nitrate, and the intrinsically stabilizing effect of polysulfide species, in determining the characteristics of lithium deposition and lithium cycling efficiency. The study illuminates the key elements underlying the unique chemistry of the lithium–electrolyte interface in Li–S batteries and it can spur further development of novel strategies toward stabilizing the lithium‐metal anode in the Li–S system.
The chemistry of the lithium–electrolyte interface in lithium–sulfur batteries is thoroughly analyzed using the anode‐free full cell configuration. This reveals detailed insights into the intricate cooperative interplay between different electrolyte components in regulating the dynamics of lithium deposition.
The development of lithium–sulfur batteries necessitates a thorough understanding of the lithium‐deposition process. A novel full‐cell configuration comprising an Li2S cathode and a bare copper foil ...on the anode side is presented here. The absence of excess lithium allows for the realization of a truly lithium‐limited Li–S battery, which operates by reversible plating and stripping of lithium on the hostless‐anode substrate (copper foil). Its performance is closely tied to the efficiency of lithium deposition, generating valuable insights on the role and dynamic behavior of lithium anode. The Li2S full cell shows reasonable capacity retention with a Coulombic efficiency of 96% over 100 cycles, which is a tremendous improvement over that of a similar lithium‐plating‐based full cell with LiFePO4 cathodes. The exceptional robustness of the Li2S system is attributed to an intrinsic stabilization of the lithium‐deposition process, which is mediated by polysulfide intermediates that form protective Li2S and Li2S2 regions on the deposited lithium. Combined with the large improvements in energy density and safety by the elimination of a metallic lithium anode, the stability and electrochemical performance of the lithium‐plating‐based Li2S full cell establish it as an important trajectory for Li–S battery research, focusing on practical realization of reversible lithium anodes.
A lithium‐limited full cell configuration for Li–S batteries that is based on lithium plating and stripping on a hostless‐anode substrate is introduced. Valuable insights are obtained on the role of lithium‐metal anode in Li–S batteries and the practical viability of this novel configuration is established.
Abstract
The development of high‐energy density batteries is critical to the decarbonization of the transportation and power generation sectors. For any given lithium‐containing cathode system, the ...anode‐free full cell configuration, which eliminates excess lithium and pairs the fully lithiated cathode with a bare current collector, can deliver the maximum possible energy density. The absence of free lithium metal during cell assembly confers significant practical advantages as well. It is also the ideal framework for developing a thorough understanding of lithium deposition in conjunction with various cathode systems. However, the poor efficiencies of lithium plating and stripping lead to rapid lithium inventory loss and poor cycle life. In the last few years, multiple studies have demonstrated the application of advanced electrolytes, modified current collectors, and optimized formation and cycling parameters to stabilize lithium deposition and improve cycle life (80% capacity retention) to 100 cycles and beyond. This review provides an overview of the various strategies toward sustaining lithium inventory in anode‐free full cells and summarizes the work undertaken in this nascent field. It is expected that further improvement upon these strategies and a combinatorial approach can enable cycle lives far in excess of what has been achieved so far.
Most simple magnesium salts tend to passivate the Mg metal surface too quickly to function as electrolytes for Mg batteries. In the present work, an electroactive salt Mg(THF)6AlCl42 was synthesized ...and structurally characterized. The Mg electrolyte based on this simple mononuclear salt showed a high Mg cycling efficiency, good anodic stability (2.5 V vs. Mg), and high ionic conductivity (8.5 mS cm−1). Magnesium/sulfur cells employing the as‐prepared electrolyte exhibited good cycling performance over 20 cycles in the range of 0.3–2.6 V, thus indicating an electrochemically reversible conversion of S to MgS without severe passivation of the Mg metal electrode surface.
Simple but effective: A simple magnesium salt Mg(THF)6AlCl42 can be used as a magnesium electrolyte that possesses a highly reversible Mg cycling efficiency, good anodic stability, and good ionic conductivity. Mg/S batteries containing the electrolyte could be cycled over 20 cycles, thus indicating electrochemically reversible conversion of sulfur into MgS.
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