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Currently, it is a significant challenge to achieve long-term cyclability and fast chargeability in lithium-ion batteries, especially for the Ni-based oxide cathode, due to severe chemo-mechanical degradation. Despite its importance, the fast charging long-term cycling behaviour is not well understood. Therefore, we comprehensively evaluate the feasibility of fast charging applications for Co-free layered oxide cathodes, with a focus on the extractable capacity and cyclability. The cathodes with a Ni content of over 80% attain 80% of their nominal capacity, along with superior cyclability under fast charging due to the suppression of the following two mechanical failure modes: (i) Li-ion concentration shock fracture (CSF) and (ii) H2-H3 phase shock fracture (HSF). In particular, CSF produces stronger stress than HSF and causes severe crack penetration in mid-Ni cathodes under fast charging. Meanwhile, HSF induces mild internal stress, but prolonged exposure accelerates mechanical degradation. To maximize the fast charging application of high-Ni cathodes, we evaluated a 5C constant current constant voltage protocol to deliver 180 mAh g -1 in 35 min, improving the cycle life by up to 89% over 100 cycles with LiNi 0.90 Mn 0.10 O 2 . This study provides insights into the fast charging applications of high-Ni cathodes, thereby advancing the understanding of their behaviour and optimization.

Lattice volume changes in Li-ion batteries active materials are unavoidable during electrochemical cycling, posing significant engineering challenges from the particle to the electrode level. In this study, we present an elastic framework coating designed to absorb and reversibly release strain energy associated with particle volume changes, thereby enhancing mechanical resilience at both the particle and electrode levels. This framework, composed of multiwalled carbon nanotubes (MWCNTs), is applied to nickel-rich LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM9055) cathodes at a low loading of 0.5 wt %, effectively mitigating critical issues such as particle cracking, volume changes, and electrode thickness variations during cycling. Leveraging these advantages, an energy-dense electrode is achieved with a high active material loading of 20 mg cm -2 , without the need for additional carbon additives. Demonstrated in a pouch cell format, this electrode achieves an exceptional capacity retention of 77.7% after 1000 cycles. This approach provides a comprehensive solution for designing Li-ion batteries capable of withstanding lattice volume variations, offering valuable insights for next-generation batteries technologies.

Dendritic challenges in Li metal batteries are commonly resolved using porous three-dimensional (3D) current collectors, which have a significant issue in that Li is deposited from the top (top growth) of the structure rather than from the bottom (bottom growth), failing to effectively suppress dendrite growth and volumetric expansion. We propose the structure incorporating a gradient lithiophilic seed within a 3D framework by pulse electroplating Mg, specifically targeting the near bottom to promote bottom growth and achieve dense Li deposition. This method achieves precise control over the catalytic seed size and distribution. Optimal conditions for maximizing the catalytic effect are identified. The resulting Mg-gradient porous-Cu structure exhibits superior Li-plating behavior with bottom growth, significantly reducing dendrite formation and improving cycle life. The mechanistic origin of bottom-guided Li growth is supported by DFT and 3D simulation results. This method presents a significant step forward in developing high-performance Li-metal batteries.

Despite the importance of the stability of the 2D catalysts in harsh electrolyte solutions, most studies have focused on improving the catalytic performance of molybdenum disulfide (MoS 2 ) catalysts rather than the sustainability of hydrogen evolution. In previous studies, the vulnerability of MoS 2 crystals is reported that the moisture and oxygen molecules can cause the oxidation of MoS 2 crystals, accelerating the degradation of crystal structure. Therefore, optimization of catalytic stability is crucial for approaching practical applications in 2D catalysts. Here, it is proposed that monolayered MoS 2 catalysts passivated with an atomically thin hexagonal boron nitride (h-BN) layer can effectively sustain hydrogen evolution reaction (HER) and demonstrate the ultra-high current density (500 mA cm⁻ 2 over 11 h) and super stable (64 h at 150 mA cm⁻ 2 ) catalytic performance. It is further confirmed with density functional theory (DFT) calculations that the atomically thin h-BN layer effectively prevents direct adsorption of water/acid molecules while allowing the protons to be adsorbed/penetrated. The selective penetration of protons and prevention of crystal structure degradation lead to maintained catalytic activity and maximized catalytic stability in the h-BN covered MoS 2 catalysts. These findings propose a promising opportunity for approaching the practical application of 2D MoS 2 catalysts having long-term stability at high-current operation., (© 2024 Wiley‐VCH GmbH.)

Zero-excess Li-metal batteries (ZE-LMBs) have emerged as the ultimate battery platform, offering an exceptionally high energy density. However, the absence of Li-hosting materials results in uncontrolled dendritic Li deposition on the Cu current collector, leading to chronic loss of Li inventory and severe electrolyte decomposition, limiting its full utilization upon cycling. This study presents the application of ultrathin (≈50 nm) coatings comprising six metallic layers (Cu, Ag, Au, Pt, W, and Fe) on Cu substrates in order to provide insights into the design of Li-depositing current collectors for stable ZE-LMB operation. In contrast to non-alloy Cu, W, and Fe coatings, Ag, Au, and Pt coatings can enhance surface lithiophilicity, effectively suppressing Li dendrite growth, thereby improving Li reversibility. Considering the distinct Li-alloying behaviors, particularly solid-solution and/or intermetallic phase formation, Pt-coated Cu current collectors maintain surface lithiophilicity over repeated Li plating/stripping cycles by preserving the original coating layer, thereby attaining better cycling performance of ZE-LMBs. This highlights the importance of selecting suitable Li-alloy metals to sustain surface lithiophilicity throughout cycling to regulate dendrite-less Li plating and improve the electrochemical stability of ZE-LMBs., (© 2024 Wiley‐VCH GmbH.)

Electroadhesive forces are crucial in various applications, including grasping devices, electro-sticky boards, electrostatic levitation, and climbing robots. However, the design of electroadhesive devices relies on speculative or empirical error approaches. Therefore, we present a theoretical model comprising predictive coplanar electrodes and protective layers for analyzing the electrostatic fields between an object and electroadhesive device. The model considers the role of protective layer and the air gap between the electrode surface and the object. To exert a higher electroadhesive force, the higher permeability of the protective layer is required. However, a high permeability of the protective layer is hard to withstand high applied voltage. To overcome this, two materials with different permeabilities were employed as protective layers-a low-permeability inner layer and a high-permeability outer layer-to maintain a high voltage and generate a large electroadhesive force. Because a low-permeability inner layer material was selected, a more permeable outer layer material was considered. A theoretical analysis revealed complex relationships between various design parameters. The impact of key design parameters and working environments on the electroadhesion behavior was further investigated. This study reveals the fundamental principles of electroadhesion and proposes prospective methods to enhance the design of electroadhesive devices for various engineering applications., (© 2024. The Author(s).)

With the growing popularity of Li-ion batteries in large-scale applications, building a safer battery has become a common goal of the battery community. Although the small errors inside the cells trigger catastrophic failures, tracing them and distinguishing cell failure modes without knowledge of cell anatomy can be challenging using conventional methods. In this study, a real-time, non-invasive magnetic field imaging (MFI) analysis that can signal the battery current-induced magnetic field and visualize the current flow within Li-ion cells is developed. A high-speed, spatially resolved MFI scan is used to derive the current distribution pattern from cells with different tab positions at a current load. Current maps are collected to determine possible cell failures using fault-simulated batteries that intentionally possess manufacturing faults such as lead-tab connection failures, electrode misalignment, and stacking faults (electrode folding). A modified MFI analysis exploiting the magnetic field interference with the countercurrent-carrying plate enables the direct identification of defect spots where abnormal current flow occurs within the pouch cells., (© 2023 Wiley-VCH GmbH.)

The adoption of Li 2 CuO 2 has drawn interest as a Li-excess cathode additive for compensating irreversible Li + loss in anodes during cycling, which would move forward high-energy-density lithium-ion batteries (LIBs). Li 2 CuO 2 provides a high irreversible capacity (>200 mAh g -1 ) in the first cycle and an operating voltage comparable with commercial cathode materials, but its practical use is still restricted by the structural instability and spontaneous oxygen (O 2 ) evolution, resulting in poor overall cycling performance. It is thus crucial to reinforce the structure of Li 2 CuO 2 to make it more reliable as a cathode additive for charge compensation. Pursuing the structural stability of Li 2 CuO 2 , herein, we demonstrate cosubstitution by heteroatoms, such as nickel (Ni) and manganese (Mn), for improving the structural stability and electrochemical performance of Li 2 CuO 2 . Such an approach effectively enhances the reversibility of Li 2 CuO 2 by suppressing continuous structural degradation and O 2 gas evolution during cycling. Our findings provide new conceptual pathways for developing advanced cathode additives for high-energy LIBs.

Li-confinable core-shell hosts have been extensively studied because they mitigate Li dendrite growth and volume change by reducing the effective current density and storing Li inside the core space during consecutive cycling. However, despite these fascinating features, these hosts suffer from unwanted Li growth on their surface (i.e., top plating) due to the carbon shell hindering Li-ion movement especially at higher current densities and capacities, resulting in poor electrochemical performance. In this study, we propose a one-dimensional porous Li-confinable host with lithiophilic Au (Au@PHCF), which is synthesized by a scalable dual-nozzle electrospinning. Because of the well-interconnected conductive networks forming three-dimensional structure, porous shell design enabling facile Li-ion transport, and hollow core space with lithiophilic Au storing metallic Li, the Au@PHCF can suppress the Li top plating and improve the Li stripping/plating efficiency compared to their counterparts even at 5 mA cm -2 , eventually achieving stable cycling performances of the LiFePO 4 full cell and Au@PHCF-Li symmetric cell for over 1000 and 2000 cycles, respectively. Finite element analysis reveals that the structural merit and lithiophilicity of Au enable fast reversible Li operation at the designated core space of the Au@PHCF, implying that the structural design of the Li-confinable host is crucial for the stable operation of promising Li-metal batteries at a practical test level.

Recently, Ni-rich layered cathode materials have become the most common material used for lithium-ion batteries. From a structural viewpoint, it is crucial to stabilize the surface structures of such materials, as they are prone to undesirable side reactions and particle cracking in which intergranular microcracks form at the particle surfaces and then propagate inside. As a simplified engineering technique for obtaining Ni-rich cathode materials with high reversibility and long-term cycling stability, we propose a facile surface coating of piezoelectric LiTaO 3 onto a Ni-rich cathode material to enhance the charge transfer reaction and surface structural integrity. Based on theoretical and experimental investigation, we demonstrate that this surface protection approach is effective at enhancing the reversibility and mechanical strength of Ni-rich cathode materials, leading to a stable cycle performance at up to 150 cycles, even at 60 °C. Furthermore, the piezoelectric characteristics of the surface LiTaO 3 can enhance the rate capability of Ni-rich cathode materials at current densities of up to 2.0C. The results of this study provide a practical insight on the development of Ni-rich cathode materials for practical use in electric vehicle applications.

Utilization of lithium (Li) metal anode is highly desirable for achieving high energy density batteries. Even so, the unavoidable features of Li dendritic growth and inactive Li are still the main factors that hinder its practical application. During plating and stripping, the solid electrolyte interphase (SEI) layer can provide passivation, playing an important role in preventing direct contact between the electrolyte and the electrode in Li metal batteries. Because of complexities of the electrolyte chemical and electrochemical reactions, the various formation mechanisms for the SEI are still not well understood. What we do know is that a strategic artificial SEI achieved through additives electrolyte can suppress the Li dendrites. Otherwise, the dendrites keep generating an abundance of irreversible Li, resulting in severe capacity loss, internal short-circuiting, and cell failure. In this minireview, we focus on the phenomenon of dendritic Li-growth and provide a brief overview of SEI formation. We finally provide some clear insights and perspectives toward practical application of Li metal batteries., (© 2021 Wiley-VCH GmbH.)

The realisation of fast-charging lithium-ion batteries with long cycle lifetimes is hindered by the uncontrollable plating of metallic Li on the graphite anode during high-rate charging. Here we report that surface engineering of graphite with a cooperative biphasic MoO x -MoP x promoter improves the charging rate and suppresses Li plating without compromising energy density. We design and synthesise MoO x -MoP x /graphite via controllable and scalable surface engineering, i.e., the deposition of a MoO x nanolayer on the graphite surface, followed by vapour-induced partial phase transformation of MoO x to MoP x . A variety of analytical studies combined with thermodynamic calculations demonstrate that MoO x effectively mitigates the formation of resistive films on the graphite surface, while MoP x hosts Li + at relatively high potentials via a fast intercalation reaction and plays a dominant role in lowering the Li + adsorption energy. The MoO x -MoP x /graphite anode exhibits a fast-charging capability (<10 min charging for 80% of the capacity) and stable cycling performance without any signs of Li plating over 300 cycles when coupled with a LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode. Thus, the developed approach paves the way to the design of advanced anode materials for fast-charging Li-ion batteries.

Silicon-based materials are the most promising candidates to surpass the capacity limitation of conventional graphite anode for lithium ion batteries. Unfortunately, Si-based materials suffer from poor cycling performance and dimensional instability induced by the large volume changes during cycling. To resolve such problems, nanostructured silicon-based materials with delicately controlled microstructure and interfaces have been intensively investigated. Nevertheless, they still face problems related to their high synthetic cost and their limited electrochemical properties and thermal stability. To overcome these drawbacks, we demonstrate the strategic design and synthesis of a gyroid three-dimensional network in a Si@SiO x /C nanoarchitecture (3D-Si@SiO x /C) with synergetic interaction between the computational prediction and the synthetic optimization. This 3D-Si@SiO x /C exhibits not only excellent electrochemical performance due to its structural stability and superior ion/electron transport but also enhanced thermal stability due to the presence of carbon, which was formed by a cost-effective one-pot synthetic route. We believe that our rationally designed 3D-Si@SiO x /C will lead to the development of anode materials for the next-generation lithium ion batteries.

The use of high-capacity electrode materials (i.e., Si) in Li-ion batteries is hindered by their mechanical degradation. Thus, oxides (i.e., SiO 2 ) are commonly used to obtain high expected capacities and long-term cycle performances. Despite extensive studies of the electrochemical-mechanical behaviors of high-capacity energy storage materials, the mechanical behaviors of amorphous SiO 2 during electrochemical reaction remain largely unknown. Here, we systematically investigate the stress evolution, electronic structure, and mechanical deformation of lithiated SiO 2 through first-principles computation and the finite element method. The structural and thermodynamic role of O in the amorphous Li-O-Si system is reported and compared with that in Si. Strong Si-O bonds in SiO 2 show high mechanical strength and brittle behavior, but as Li is inserted, the Li-rich SiO 2 phases become mechanically softened. The relaxation kinetics of SiO 2 , inducing deviatoric inelastic strains under mechanical constraints, is also compared with that of Si. The finite element model including the kinetic model for anisotropic expansion demonstrates that the long-term cycling stability of core-shell Si-SiO 2 nanoparticles mainly arises from the reaction kinetics and high mechanical strength of SiO 2 . These results provide fundamental insights into the chemomechanical behavior of SiO 2 for practical use.

This study presents a simple and effective method of reducing amorphous silica (a-SiO2 ) with Ti metal through high-energy mechanical milling for improving its reactivity when used as an anode material in lithium-ion batteries. Through thermodynamic calculations, it is determined that Ti metal can easily take oxygen atoms from a-SiO2 by forming a thermodynamically stable SiO2-x /TiOx composite, meaning that electrochemically inactive a-SiO2 is partially reduced by the addition of Ti metal powder during milling. This mechanically reduced SiO2-x /TiOx composite anode exhibits a greatly improved electrochemical reactivity, with a reversible capacity of more than 700 mAh g(-1) and excellent cycle performance over 100 cycles. Furthermore, an enhancement in the mechanical and thermal stability of the composite during cycling can be mainly attributed to the in situ formation of the SiO2-x /TiOx phase. These findings provide new insight into the rational design of robust, high-capacity, Si-based anode materials, as well as their reaction mechanism., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)