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We introduce a paradigm of solvent and binder selection for solution-processing Li6PS5Cl solid-state electrolyte particles based on Hansen solubility parameters. Treatment of the Li6PS5Cl in selected solvents results in particle morphological change, but crystallographic structure remains intact. Although solution processing reduced the Li6PS5Cl ionic conductivity, it promotes interfacial stability by alleviating reduction of the solid electrolyte in contact with Li metal. These findings have the potential to enhance the stability, structural integrity, and performance of sulfide solid-state electrolytes in practical applications. [ABSTRACT FROM AUTHOR]

Highlights: A critical assessment of electrolytes' limiting factors, which affect the low-temperature performance of Li-metal batteries. Summary of emerging strategies to improve low-temperature performance from the aspects of electrolyte design and electrolyte/electrode interphase engineering. Perspectives and challenges on how to develop creative solutions in electrolytes and correlative materials for low-temperature operation. Electrolyte design holds the greatest opportunity for the development of batteries that are capable of sub-zero temperature operation. To get the most energy storage out of the battery at low temperatures, improvements in electrolyte chemistry need to be coupled with optimized electrode materials and tailored electrolyte/electrode interphases. Herein, this review critically outlines electrolytes' limiting factors, including reduced ionic conductivity, large de-solvation energy, sluggish charge transfer, and slow Li-ion transportation across the electrolyte/electrode interphases, which affect the low-temperature performance of Li-metal batteries. Detailed theoretical derivations that explain the explicit influence of temperature on battery performance are presented to deepen understanding. Emerging improvement strategies from the aspects of electrolyte design and electrolyte/electrode interphase engineering are summarized and rigorously compared. Perspectives on future research are proposed to guide the ongoing exploration for better low-temperature Li-metal batteries. [ABSTRACT FROM AUTHOR]

Lithium metal is regarded as the most promising anode material for next generation high energy density lithium batteries due to its high theoretical capacity and lowest potential versus standard hydrogen electrode. However, lithium dendrite growth and huge volume change during cycling hinder its practical application. It is of great importance to design advanced Li metal anodes to solve these problems. Herein, we report a ZnO-coated Zn foam as the host matrix to pre-store lithium through thermal infusing, achieving a Zn@ZnO foam supported Li composite electrode (LZO). Needlelike ZnO nanofibers grown on the Zn foam greatly increase the surface area and enhance the lithiophilicity of the Zn foam. In situ formed synaptic LiZn layer after lithium infusion can disperse local current density and lower Li diffusion barrier effectively, leading to homogeneous Li deposition behavior, thus suppressing dendrite formation. The porous Zn foam skeleton can accommodate volume variation of the electrode during long-term cycling. Benefiting from these merits, the LZO anode exhibits much better cycle stability and rate capability in both symmetrical and full cells with low voltage hysteresis than the bare Li anode. This work opens a new opportunity in designing high performance composite Li anode for lithium-metal batteries. [ABSTRACT FROM AUTHOR]

An interlayer is usually employed to tackle the interfacial instability issue between solid electrolytes (SEs) and Li metal caused by the side reaction. However, the failure mechanism of the ionic conductor interlayers, especially the influence from electron penetration, remains largely unknown. Herein, using Li1.3Al0.3Ti1.7(PO4)3 (LATP) as the model SE and LiF as the interlayer, we use metal semiconductor contact barrier theory to reveal the failure origin of Li/LiF@LATP interface based on the calculation results of density functional theory (DFT), in which electrons can easily tunnel through the LiF grain boundary with F vacancies due to its narrow barrier width against electron injection, followed by the reduction of LATP. Remarkably, an Al-LiF bilayer between Li/LATP is found to dramatically promote the interfacial stability, due to the highly increased barrier width and homogenized electric field at the interface. Consequently, the Li symmetric cells with Al-LiF bilayer can exhibit excellent cyclability of more than 2,000 h superior to that interlayered by LiF monolayer (∼ 860 h). Moreover, the Li/Al-LiF@LATP/LiFePO4 solid-state batteries deliver a capacity retention of 83.2% after 350 cycles at 0.5 C. Our findings emphasize the importance of tuning the electron transport behavior by optimizing the potential barrier for the interface design in high-performance solid-state batteries. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal is considered to be the most ideal anode for rechargeable Li-metal batteries due to its high theoretical specific capacity and low redox potential. However, the Li dendrite problem associated with Li metal anodes limits its practical application. Herein, a new chemical dealloying method that adjust the pore structure formed during chemical dealloying at room temperature to prepare a porous Copper current collector which was to enable dendrite-free Li deposition. Benefiting from the naturally formed suitable size and uniform porous structure, this current collector provides larger surface area to homogenize the Li ion distribution and promote dendrite-free Li metal anode with improved Coulombic efficiency (96% for over 210 cycles at the current density of 0.5 mA cm−2 and 95% for 80 cycles at 1.0 mA cm−2). This work provides a novel way to suppress Li dendrite. [ABSTRACT FROM AUTHOR]

The metallic lithium (Li) is considered as the most promising anode material for high-energy batteries. Nevertheless, the uncontrollable growth of Li dendrite and unstable electrolyte/electrode interface still hinder the development of Li-based battery. In this work, a novel strategy has been proposed to stabilize Li anode by in-situ polymerizing polypyrrole (PPy) layer on Ni foam (PPy@Ni foam) as an artificial protective layer. The PPy protective layer can effectively decrease the contact between Li metal and electrolyte during cycling. In addition, the morphology characterization shows that the PPy layer can help the even Li deposition underneath the layer, leading to a dendrite-free Li anode. As a result, when deposited 2 mAh•cm−2 Li metal, the PPy@Ni foam can keep stable Coulombic efficiency (99%) during nearly 250 cycles, much better than the pure Ni foam (100 cycles). Even in the case of the Li capacity of 10 mAh•cm−2, the stable cycling performance for 60 cycles can still be achieved. Furthermore, when assembled with LiFePO4 material as the cathode for a full cell, the PPy@Ni foam can keep high capacity retention of 85.5% at 500 cycles. In our work, we provide a simple and effective method to enhance the electrochemical performances of Li metal-based batteries, and reveal a new avenue to design three-dimensional (3D) metallic current collector for protecting the Li metal anode. [ABSTRACT FROM AUTHOR]