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The conformal surface coating of Ni-rich layered cathode materials is essential for mitigating their interfacial and subsequent structural degradation. The zirconia (ZrO2) coating effectively enhances the surface stability of the cathode owing to its excellent chemical durability; however, the insulating electrical conductivity of ZrO2 increases the electrode resistance and triggers efficiency decay. Here, we propose highly conductive oxygen-deficient black ZrO2−x as a charge-conductive coating material. The black ZrO2−x is uniformly coated onto the Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC) surface via a solvent-free mechanochemical shearing process. Benefiting from the black ZrO2−x coating layer, black ZrO2−x coated NMC shows improved cycling characteristics and better rate capability than both bare NMC and ZrO2 coated NMC. The enhanced electrochemical performance by the conformal coating of black ZrO2−x mainly results from enhanced charge transfer, reduced gas evolution, and mitigated microstructural cracking. Density functional theory calculations confirm that the defective structure of black ZrO2−x lowers the energy barrier for Li ion transfer, and strong hybridization between Zr in black ZrO2−x and O in NMC mitigates oxygen evolution. [ABSTRACT FROM AUTHOR]

Lithium–oxygen (Li–O2) batteries, recognized as candidates for the highest energy storage, face challenges of irreversibility and low efficiency due to insulating discharge products. Addressing these issues, our study explores innovative dual-atom catalysts (DACs) comprising non-precious metals, specifically atomically scaled nickel (Ni) and iron (Fe), positioned on defective mesopore sites of nitrogen-doped carbon nanotubes (NCNTs) to enhance battery performance. We successfully achieved the synthesis of both homogeneous (Fe–Fe-NCNTs and Ni–Ni-NCNTs) and heterogeneous (Ni–Fe-NCNTs and Fe–Ni-NCNTs) DACs on NCNTs, by varying the loading sequences and combination of Ni and Fe. Our findings demonstrate that Fe-first-loaded DACs, particularly heterogeneous Ni–Fe-NCNT variants, excelled in both NO2− mediation reactivity and catalytic activity, achieving a longer lifespan of 200 cycles and maintaining consistent ORR/OER overpotential. Insights into the mesoporous loading sites and reaction mechanisms of these DACs in Li–O2 cells were gained through density functional theory calculations. This research paves the way for replacing costly noble metal catalysts with tailored non-noble metal combinations, potentially revolutionizing Li–O2 cell technology and broadening applications in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Graphite is used as an anode material in commercial lithium-ion batteries (LIBs) because of its stable cycling characteristics and high reversibility. However, during fast charging, the deposition of Li metal on the graphite electrode surface becomes problematic because the potential at which Li metal deposition occurs would be close to 0 V (vs. Li/Li+). In this study, we demonstrated an improvement in the fast-charging performance through the effective suppression of Li deposition on the anode surface during fast charging. This was achieved by introducing a metal phosphide nanodot coating layer onto artificial graphite particles. Through various analyses, including density functional theory (DFT) calculations, it was found that the cobalt phosphide(CoP) coating layer increased the concentration of PF6− anions in the inner Helmholtz layer (IHL), which in turn induced the formation of an anion-derived solid-electrolyte interface (SEI) layer. A CoP-artificial graphite (AG)/NCM 811 full cell exhibited a high capacity retention (88%) after 300 cycles, without any Li deposition. We also verified the impact of other types of metal phosphides on the fast-charging performance of LIBs. Our findings suggest that the rational design of the SEI layer is feasible through simple surface modifications that induce changes in the properties of the electric double layer. This provides a novel perspective for the design of materials suitable for the rapid charging of LIBs. [ABSTRACT FROM AUTHOR]

Reframing ionic transport and interface chemistry through electrolyte renovation is essential to promote the fast charging of Li-ion batteries, even under extreme conditions. Despite the formation of a less resistive interface using high-concentration electrolytes (HCEs), their inevitably high viscosity compromises their practical use. This work aims to explore the most suitable hydrofluoroether diluents for localized-high-concentration electrolytes (LHCEs). Contrary to the consensus on their negligible intervention in the Li+ solvation sheath, experimental evidence, and simulation studies have revealed that diluents can partially penetrate solvation and enable intermolecular interactions with solvents and additives. While the extent of physical intervention is similar, the intermolecular binding becomes greater when using longer-chain diluents with increased –CF2– moieties, hindering the desired interfacial reactions. By strategically selecting smaller diluents with fewer –CF2– units, low-viscosity LHCEs can attain the long stable cycling of Li-ion cells at a 10 minute charging rate (∼18 mA cm−2) over 500 cycles, and facilitate reliable performance under demanding conditions, such as thick electrodes (∼5 mAh cm−2) and low temperatures (−20 °C). [ABSTRACT FROM AUTHOR]

All-solid-state Li-ion batteries (ASSBs) are considered as ideal next-generation energy storage devices owing to their safe operation and high energy densities. Recently, halide-based solid electrolytes (SEs) have come under the spotlight because of their wide electrochemical stability windows and high ionic conductivities. However, their usage as coating materials for cathodes is limited. To examine the wide electrochemical stability window of SEs for lithium-metal anodes and their interfacial stability with high-voltage cathodes, a systematic first-principles investigation of A-site cation and anion exchange in Li3MX6 (M: Lu, Sc, Bi, In, Y, Tm, Dy, Ho, Er, Tm, Sm, Tb; X: Br, Cl, and I) was conducted. The systematic analysis showed that the electrochemical behavior of chloride SEs can be modulated by mixing M3+ cations. Furthermore, the replacement of M3+ by Zr4+ and the anionic blending of Br with Cl, which exhibits a relatively high ionic conductivity, was also computed for comparison with the A-site cation-mixed halide electrolyte. Our computational work provides an overview of the evolution of lithium halide SEs in high-voltage ASSBs. [ABSTRACT FROM AUTHOR]

In this study, microwave irradiation is employed for the phenolation of acid-insoluble Klason lignin. Microwave irradiation significantly reduces the reaction temperature (180 → 100 °C) and time (6 h → 10 min) without noticeable differences in the chemical structure of the phenolated lignin compared with the products prepared using a conventional heating method. As the reaction temperature increases (100 → 150 °C), lignin decomposition and crosslinking occur simultaneously, as did phenolation. Upon increasing the phenol-to-lignin ratio, the fragmentation of lignin is enhanced, while the crosslinking reaction is inhibited, leading to a decrease in the molecular weight and glass transition temperature of the phenolated lignin. Density functional theory is applied to elucidate the thermal and non-thermal effects of the electromagnetic field on the phenolation of Klason lignin. The solubility of Klason lignin in tetrahydrofuran and methanol is highly enhanced after phenolation, which allows for its adhesive application on glass, polyethylene naphthalate, and polyimide substrates. [ABSTRACT FROM AUTHOR]

The structural engineering of crystal frameworks has emerged as a highly useful technique in the development of perovskite solar cells (PSCs) to realize highly efficient devices with superior chemical and electrical properties. The introduction of organic spacer cations into perovskite crystals is one of the major topics currently being explored in the field of structural engineering research. However, intercalated organic molecules in three-dimensional (3D) perovskite structures generate low-dimensional perovskite phases, resulting in inefficient carrier transport due to a reduction in 3D dimensionality. Maintaining the 3D crystal structures of organic-cation-inserted perovskites remains a major issue and a challenging task to be solved. In this work, we created an ideal organic-layered 3D crystal structure using an n-butylammonium (n-BA) halide salt in a FA0.83Cs0.17Pb0.5Sn0.5I3 perovskite. The cation allows a self-assembled hierarchical structure in which the n-BA organic analog is layered on the surface and at the bottom of the perovskite without a reduction of the 3D crystal dimensionality. Based on X-ray scattering results, the existence of a vertically oriented crystal structure, from both external and internal structural perspectives, demonstrates the creation of an ideal n-BA-capped 3D perovskite crystal. Furthermore, the self-assembling n-BA cations facilitate an enhancement of the device stability of Pb–Sn PSCs, due to the suppression of the generation of silver iodide at the top interface and the degradation of PSS in poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) by sulfuric acid at the bottom interface. These structural and chemical stability effects lead to the creation of a highly efficient Pb–Sn PSC with nearly 19% efficiency. [ABSTRACT FROM AUTHOR]

The utilization of lithium (Li) metal is highly desirable, because it is the most attractive anode for high-energy Li batteries, even if there are problems with the unpredictable phenomena of dendritic growth and dead-Li during repeated plating-stripping. So far, the issue of branch-like uneven Li plating has still not been resolved. Recently, using a highly concentrated salt-electrolyte (lithium bis(fluorosulfonyl with a LiNO3 additive)) was recognized as the most straightforward approach, although its critical role still remains elusive. Herein, we investigated the overpotential of metallic Li anodes with electrolytes having different salt concentrations and verified the microscopic origins of Li growth, as observed by in situ optical microscopy. We argue that the high ionic conductivity of the electrolyte together with its solid-state interphase effectively suppresses the local potential and concentration gradients, resulting in highly dense dendrite-free Li plating, as supported by in-depth numerical analysis. Our findings provide clear insights that can pave the way to further improvements of the performance of Li metal anodes up to the theoretical limit (3860 mA h g−1). [ABSTRACT FROM AUTHOR]

Designing a fast ionic conductor has been an essential issue in next-generation batteries based on all-solid-state systems, with specific application targets in large-scale energy storage devices. For this wide range of applications, high levels of ionic conductivity, as well as safety, should be preferentially ensured. However, current solid electrolyte technology is unable to meet the high standards of acceptable conductivity and becomes more problematic in multivalent-ion batteries. Herein, we have proposed a novel phase-convertible ionic conductor based on a monolithic succinonitrile (SN) plastic crystalline material. The unique properties of SN, with high polarity and high rotational degrees of freedom, enable it to dissolve Mg salts and allow for fast transport of cations in the solid phase. For the first time, a high Mg2+ ion conductivity of 2.8 × 10−5 S cm−1 was demonstrated at room temperature, and high chemical and thermal stabilities with a wide electrochemically stable window were proven. The monolithic SN structure was able to process simple phase transitions between liquids and solids; therefore, the highly deformable phase-convertible ionic conductor enabled the formation of excellent conformal contact with the electrode. In addition, the origin of the high conductivity was theoretically investigated through density functional theory calculations. We believe that the unique host of monolithic SN is a useful platform with potential applicability for most kinds of cation with fast ion-conducting properties. [ABSTRACT FROM AUTHOR]

Realizing Li-metal batteries requires overcoming several hurdles, such as volume changes, a thickening solid electrolyte interphase, and safety issues associated with uncontrollable Li growth. Introducing a 3D conductive framework that improves Li reversibility by decreasing the local current density and alleviating volume changes can mitigate these issues, but inevitable Li growth on the top surface remains problematic. To address this, herein, we report an electrical conductivity-controlled 3D host consisting of a glass fiber (GF) framework, size-/conductivity-controlled partially reduced graphene oxide (PrGO), and a Cu substrate (PrGO–GF/Cu). Due to the synergistic interplay between the 3D GF alleviating volume fluctuation and PrGO with desirable conductivity, the PrGO–GF/Cu host mitigates the Li top plating and guides preferential Li deposition/dissolution at the bottom of the structure. As a result, the PrGO–GF/Cu exhibits substantially improved electrochemical performance in coulombic efficiency, symmetric cell, and LiFePO4 full cell tests. Experimental and theoretical studies reveal that modulating the electrical conductivity of the framework within an optimal range is an easy and effective way of suppressing Li top plating and facilitating Li bottom plating/stripping. This work demonstrates the importance of controlling the electrical conductivity to enable reversible behavior of Li in the Li-metal host anode, and a facile method to fabricate a 3D host that prevents Li top plating. [ABSTRACT FROM AUTHOR]

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.