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The crucial issue of wettability in high-energy-density lithium-ion batteries (LIBs) has not been comprehensively addressed to date. To overcome the challenge, state-of-the-art LIBs employing a ceramic-coated separator improves the safety- and wettability-related aspects of LIBs. Here, we present a mechanistic study of the effects of a ceramic-coated layer (CCL) on electrode wettability and report the optimal position of the CCL in LIBs. The electrolyte wetting was investigated using the multiphase lattice Boltzmann method and electrochemical impedance spectroscopy for capturing the electrolyte-transport dynamics in porous electrodes and impedance spectra in pouch-type LIBs, respectively. Results indicate that the CCL caused the velocity vector to transport the electrolyte further, resulting in an increase in the wetting rate. Moreover, the location of the CCL considerably affected the wettability of the LIBs. This study provides mechanical insight into the design and fabrication of high-performance LIBs by incorporating CCLs.

Three-dimensional (3D) porous frameworks have attracted considerable interest as lithium-metal electrodes for next-generation rechargeable batteries. The high surface areas and large pore volumes o...

All-solid-state batteries (ASSBs) offer a fundamental solution to mitigate the safety and reliability issues of conventional lithium-ion batteries utilizing flammable liquid electrolytes. However, interfacial resistances between the cathode materials and solid electrolytes, which originate from poor solid-solid contacts and detrimental interfacial reactions, limit the electrochemical performances of ASSBs. Recently, various approaches have been developed to realize high-capacity composite cathodes with improved cycling stability. For example, single-crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) has been reported to mitigate the capacity fading resulting from cracking of commonly adopted multi-crystal NCM811. Also, halide-type solid electrolytes are reported to exhibit high Li-ion conductivity and electrochemical stability with NCM. In this work, we systematically study the interfacial and charge-transport impedances of NCM composite cathodes with halide solid electrolytes. The composite cathodes comprising single- or multi-crystal NCM811 and Li6PS5Cl or Li3InCl6 (and conductive agents) are fabricated to characterize their electrochemical impedance behaviors. In particular, we analyze the evolution of the interfacial and charge-transport impedances during charge–discharge cycling based on a multi-rail transmission line model combined with interfacial reactions. In addition, we investigate the chemical, electrochemical, and mechanical degradations of composite cathodes using various analytical tools to elucidate performance-determining factors of ASSBs.

Lithium-metal electrodes are of particular interest for next-generation rechargeable batteries because of their high specific capacity and low redox potential. Therefore, Li-metal-based batteries may afford higher energy densities than commercially available Li-ion batteries with graphite anodes. However, various bottlenecks have hampered the commercial development of these batteries, including uncontrolled Li dendrite formation and huge volume changes during cycling. Consequently, Li-metal batteries suffer from low Coulombic efficiency and poor cycling stability. In recent years, there has been extensive research on the design and construction of three-dimensional (3D) porous electrodes that can host metallic Li. However, the low pore utilization and uneven Li plating remain crucial issues. This can be understood in terms of electronic and ionic transport through the framework electrode. The carbon frameworks exhibit high electronic conductance; however, large resistance to Li+ migration in the electrolytes of internal and interparticle pores inhibits the penetration of Li+ deep into the electrode. In this work, we demonstrate that a strong interaction between Li and a lithiophilic nanolayer on a substrate plays a critical role in enhancing pore utilization in carbon framework electrodes. As a model architecture, we examine a Li storage process in a framework electrode consisting of porous carbon derived from metal-organic frameworks (MOFs) and a galvanically displaced Ag layer on a Cu substrate (Cu@Ag). The electrochemical experiments combined with operando XRD measurements and microstructural characterizations suggest that a lithiophilic Ag on the Cu substrate preferentially reacts with Li+ to form Li x Ag during the initial stage of Li plating. This Li x Ag phase acts as a seed that can regulate the subsequent Li plating, promoting confined Li storage in the carbon framework electrode while suppressing top plating. Because of these advantages, the MOF-C framework electrode on Cu@Ag exhibits better cycling stability (>250 cycles) than the MOF-C framework electrode on Cu (140cycles). However, when the thickness of the MOF-C framework is increased to 90 μm, the diffraction peak for Ag remains dominant throughout Li plating-stripping, and the formation of Li x Ag alloys is not clearly detectable in the diffraction patterns, suggesting that only a limited amount of Ag is involved in the alloying reaction with Li+. Based on the computational studies, the efficacy of lithiophilic layers toward improving pore utilization is discussed in terms of the kinetic competition between Li+ transport through porous channels and the interfacial reaction of Li+ with the substrate. This study conveys an important message that the Li-substrate interaction plays a vital role in promoting the confined Li storage; hence, it should be considered a key design factor for porous carbon frameworks with high capacity and long cycle lifetime. References Yun, H. R. Shin, E.-S. Won, H. C. Kang, J.-W. Lee, Confined Li metal storage in porous carbon frameworks promoted by strong Li-substrate interaction, Chem. Eng. J. 430 (2022) 132897. Jin, Y. Ye, Y. Niu, Y. Xu, H. Jin, J. Wang, Z. Sun, A. Cao, X. Wu, Y. Luo, H. Ji, L. J. Wan, Solid-solution-based metal alloy phase for highly reversible lithium metal anode, J. Am. Chem. Soc. 142 (2020) 8818–8826. Kim, J. Lee, J. Yun, S.H. Choi, S.A. Han, J. Moon, J.H. Kim, J.-W. Lee, M.-S. Park, Functionality of dual-phase lithium storage in a porous carbon host for lithium-metal anode, Adv. Funct. Mater. 30 (2020) 1910538.

In recent years, the industrial requirements for rechargeable batteries in terms of energy density have continuously increased owing to the widespread adoption of portable electronic devices and electric vehicles. Li metal has been identified as a promising anode material to meet the ever-increasing demand for rechargeable batteries with high energy densities because of its low redox potential (−3.04 V vs. standard hydrogen electrode)and high specific capacity (3860 mAh g−1) [1]. Despite these advantages, the commercial use of Li metal anodes has been hindered by unresolved critical issues, such as the uncontrollable growth of Li dendrites and the severe volume changes during cycling. In practice, the dendritic growth of Li deposits causes the formation of dead Li species and triggers internal short-circuiting of batteries during cycling, leading to a significant loss of reversibility and raising safety concerns. Moreover, large volume changes in the Li metal anode during Li plating–stripping, which originate from the “hostless” character of the Li metal, impose severe stresses on the solid–electrolyte interphase (SEI) layers, and thus reducing the mechanical stability of SEIs. Once the SEI layers are cracked or fractured, bare Li metal is exposed to the electrolyte, leading to the continuous formation of thick SEI layers on the anode surface. This is mainly responsible for the continuous, irreversible loss of active Li, i.e., low Coulombic efficiency and short cycle lifetimes. 3D “host” architectures are beneficial for securing the dimensional stability of Li metal anodes by utilizing internal pores (i.e., free-spaces) as reservoirs for Li storage. Moreover, they provide large active surface areas and hence reduce the effective current densities, suppressing uneven Li plating (dendritic growth) during high-rate operations. Metal-organic framework (MOF)-derived carbon offers many advantages over conventional carbon materials in terms of specific surface area, pore volume, and structural tunability. Furthermore, the critical role of atomically dispersed heteroatoms has been verified in reducing the energy barriers for the nucleation and growth of Li [2]. Herein, we report MOF-derived porous carbon hosts with strong Li–host interactions achieved by galvanically displaced lithiophilic seeds. Owing to the distinctive chemical and structural nature of zeolitic imidazolate frameworks (ZIF-8), atomically dispersed Zn can be spontaneously replaced by Ag with a strong lithiophilicity via a galvanic displacement (GD) reaction. Based on a comparative study of carbon hosts with different sizes, morphologies, and distributions of Ag, in particular, we assess the efficacy of lithiophilic Ag in promoting reversible Li storage inside porous carbon hosts. The strong Li–host interactions enabled by lithiophilic Ag effectively reduce the overpotentials for nucleation and growth of Li, and more importantly, the role of lithiophilic Ag in governing the reversibility of Li plating–stripping is discussed in terms of the spatial distribution characteristics of Ag. The atomically dispersed Ag triggers the outward growth of Li from the internal pores of the carbon host, showing a stable cycling performance (>745 cycles). Contrarily, the surface-anchored Ag nanoparticles induce uneven Li plating on the outer surface of the carbon host, resulting in a rapid performance drop (~305 cycles) during cycling. This work provides new insights into the development of advanced 3D host materials for reversible Li metal anodes by utilizing strong Li–host interactions. References [1] Z.P. Cano, D. Banham, S. Ye, A. Hintennach, J. Lu, M. Fowler, Z. Chen, Batteries and Fuel Cells for Emerging Electric Vehicle Markets, Nat. Energy 3 (2018) 279–289. [2] J. Yun, H. R. Shin, E.-S. Won, H. C. Kang, J.-W. Lee, Confined Li Metal Storage in Porous Carbon Frameworks Promoted by Strong Li-Substrate Interaction, Chem. Eng. J. 430 (2022) 132897.

A rechargeable lithium–oxygen battery (LOB) operates via the electrochemical formation and decomposition of solid-state Li2O2 on the cathode. The rational design of the cathode nanoarchitectures is thus required to realize high-energy-density and long-cycling LOBs. Here, we propose a cathode nanoarchitecture for LOBs, which is composed of mesoporous carbon (MPC) integrated with carbon nanotubes (CNTs). The proposed design has the advantages of the two components. MPC provides sufficient active sites for the electrochemical reactions and free space for Li2O2 storage, while CNT forests serve as conductive pathways for electron and offer additional reaction sites. Results show that the synergistic architecture of MPC and CNTs leads to improvements in the capacity (~ 18,400 mAh g− 1), rate capability, and cyclability (~ 200 cycles) of the CNT-integrated MPC cathode in comparison with MPC.

Li metal suffers from uncontrollable dendrite formation and huge volume changes during cycling, resulting in shortened cycle lifetimes. Porous carbon frameworks have been explored as host materials to store Li metal; however, the low pore utilization and uneven Li plating remain crucial issues. Herein, we demonstrate that a strong interaction between Li and substrate plays a critical role in enhancing pore utilization in the carbon framework electrodes, thus improving their cycle lifetimes. As a model architecture, we examine a Li storage process in a framework electrode consisting of porous carbon derived from metal–organic frameworks (MOFs) and a galvanically displaced Ag layer on a Cu substrate. The MOF-derived carbon framework electrode on the Ag-deposited Cu substrate exhibits significantly better cycling stability (>250 cycles) than the electrode on bare Cu (140 cycles). In-operando synchrotron X-ray diffraction studies combined with microstructural characterizations reveal that the lithiophilic Ag on the substrate preferentially reacts with Li+ to form LixAg during the initial stage of Li plating and promotes confined Li storage in the carbon framework electrode while suppressing top plating. However, the Ag layer is found to lose its effectiveness when the thickness of the electrode exceeds a critical value. Based on simulation studies, the efficacy of lithiophilic layers toward improving pore utilization is discussed in terms of the kinetic competition between Li+ transport through porous channels and the interfacial reaction of Li+ with the substrate, which can provide a guideline for designing porous carbon frameworks with high capacity and long cycle lifetimes.

Ether-based organic liquid electrolytes (OLEs) have been commonly used in lithium–oxygen batteries (LOBs); however, they become unstable and cause rapid performance degradation during LOB operation. To address these problems, in this study we propose an OLE-free cathode architecture based on a Li+-selective solid membrane (LSSM). An LSSM with a seamless duplex (dense/porous) architecture is prepared by a tape casting process combined with co-sintering, and carbon nanotubes (CNTs) decorated with Au nanoparticles (CNT@Au) are directly formed on its porous framework. We show that the duplex-LSSM can effectively protect the metallic Li anode from parasitic reactions with impurity species and improve the cycling stability of Li. Furthermore, an LOB assembled with the duplex-LSSM and CNT@Au components exhibits a discharge capacity as high as 3650 mAh g−1 and improved cycling stability (>140 cycles) compared to a conventional OLE-based LOB; this can be explained in terms of the combined advantages provided by the OLE-free cathode and the LSSM-protected Li anode.

Lithium-metal is considered a promising anode material for rechargeable batteries, owing to its high specific capacity of 3,860 mAh g-1 and low redox potential. However, various technical challenges, such as uneven Li deposition and large volume expansion, need to be addressed for the development of rechargeable Li-metal batteries. In recent years, there has been extensive research on the design and construction of three-dimensional (3D) porous electrodes that can host metallic Li. In practice, inhomogeneous nucleation and dendritic growth of Li still occur on top of the 3D host electrodes due to the kinetic limitation of Li+ in electrolyte-filled pores. In this work, we propose an interfacial activity gradient design to promote the bottom-up growth of Li in the 3D-Cu host electrode while suppressing the top growth. The Li plating behavior of the 3D-Cu host electrode is analyzed using a theoretical model based on a modified transmission line. Based on the theoretical results, a conformal lithiophilic nanolayer is formed via galvanic displacement to activate Li nucleation over the bottom, whereas an inert, non-conductive coating passivates the top surface. The 3D-Cu electrode with the interfacial activity gradient shows considerable improvements in Coulomic efficiency and cycling stability during repeated Li plating-stripping, compared to the conventional electrode with uniform interfacial activity. Our study demonstrates that the interfacial activity gradient design may provide an effective approach to developing highly efficient and robust Li metal electrodes based on 3D porous architectures.