Combining Multiple-Element Doping of LiCoO and Bilayer Electrolytes for 4.6 V High-Voltage All-Solid-State Lithium Batteries.

The halide electrolyte LiInCl has been proposed to function as a barrier layer between LiCoO and solid electrolytes LiPSCl, aimed at mitigating interfacial issues. Here we reveal that the employment of LiInCl as a barrier layer is still ineffective for the LiCoO cathode due to the oxygen redox on the surface and the irreversible phase transition of LiCoO at a high voltage of 4.6 V.

A Ring-Shaped Lithium Metal Anode Enables High-Performance All-Solid-State Batteries Revealed by In Situ L-Band EPR Imaging.

In traditional operations of all-solid-state lithium metal batteries (ASSLMBs), a small thin lithium metal circular disk is employed as a lithium metal anode (LMA). However, ASSLMBs with a circular-disk LMA often fail in <150 cycles with low capacity retention. In this work, we developed a new ring-shaped LMA to improve cyclability.

Visualizing Lithium Deposition and Identifying Two Types of Dendrites in Extreme-Fast-Charging Full Cells across the Entire Lifespan by EPR and EPR Imaging.

Metallic lithium deposition processes in NCM811∥graphite full cells during extreme-fast charging of 4 C (fully charged within 15 min) are detected via electron paramagnetic resonance (EPR) and EPR imaging over hundreds of cycles to quantify lithium deposits and visualize their spatial distribution. EPR imaging shows that constant-voltage charge generates loose Li dendrites with divergent growth whereas overcharge leads to long dendrites with vertical growth, and these Li deposits accumulate at the anode edges, which could deplete the Li resource at the cathode edges. Moreover, quantitative EPR indicates that the stripping current correlates to the deposit surface areas, while the reintercalation current depends on the contact areas between plated Li and graphite.

Evident structural anisotropies arising from near-zero particle asphericity in granular spherocylinder packings.

With magnetic resonance imaging experiments, we study packings of granular spherocylinders with merely 2% asphericity. Evident structural anisotropies across all length scales are identified. Most interestingly, the global nematic order decreases with increasing packing fraction, while the local contact anisotropy shows an opposing trend.

Interplay between Intermediate Anionic and Cationic Species and the Reflection to Voltage Hysteresis of Oxygen-Redox Battery Electrodes: A Holistic Picture.

Ligand-to-metal charge transfer (LMCT) is conceived as a universal theory to account for voltage hysteresis in oxygen-redox battery electrodes. However, the influence of oxygen anionic species on mediating LMCT and its reflection to voltage hysteresis remain poorly understood. Herein, we demonstrate a close interplay between the chemical states of oxidized oxygen species, the cationic species, and the kinetics of LMCT and forcefully identify their influence on the magnitude of voltage hysteresis.

Destabilization of Oxidized Lattice Oxygen in Layered Oxide Cathode.

Integrating anion-redox capacity with orthodox cation-redox capacity is deemed as a promising solution for high-energy-density battery cathodes surmounting the present technical bottlenecks. However, the evolution of oxidized oxygen species during the electrochemical or chemical process easily jeopardizes the reversibility of oxygen redox and remains poorly understood. Herein, we showcase the gradual conversion of the π-interacting oxygen (localized hole states on O) to the σ-interacting oxygen upon resting at a high voltage for P3-type NaLiMnO with nominally stable ribbon-like superstructure, accompanied by the O-O dimerization and the local structural reorganization.

From Oxygen Redox to Sulfur Redox: A Paradigm for Li-Rich Layered Cathodes.

The utilization of anionic redox chemistry provides an opportunity to further improve the energy density of Li-ion batteries, particularly for Li-rich layered oxides. However, oxygen-based hosts still suffer from unfavorable structural rearrangement, including the oxygen release and transition metal (TM)-ion migration, in association with the tenuous framework rooted in the ionicity of the TM-O bonding. An intrinsic solution, by using a sulfur-based host with strong TM-S covalency, is proposed here to buffer the lattice distortion upon the highly activating sulfur redox process, and it achieves howling success in stabilizing the host frameworks.

Sustainable Anionic Redox by Inhibiting Li Cross-Layer Migration in Na-Based Layered Oxide Cathodes.

The irrational utilization of an anionic electron often accompanies structural degradation with an irreversible cation migration process upon cycling in sodium-layered oxide cathodes. Moreover, the insufficient understanding of the anionic redox involved cation migration makes the design strategies of high energy density electrodes even less effective. Herein, a P3-NaLiFeMnO (P3-NLFM) cathode is proposed with the in-plane disordered Li distribution after an in-depth remolding of the Li ribbon-ordered P3-NaLiMnO (P3-NLM) layered oxide.

NaCrZrCl: A New Halide-Based Fast Sodium-Ion Conductor.

All-solid-state batteries employing solid electrolytes (SEs) have received widespread attention due to their high safety. Recently, lithium halides are intensively investigated as promising SEs while their sodium counterparts are less studied. Herein, a new sodium-ion conductor with a chemical formula of NaCrZrC is reported, which exhibits high room temperature ionic conductivity of 0.

Approaching Effective Differential Centrifugal Fractionation by Combining Image Analysis with Analytical Ultracentrifugation.

Centrifugation is one of the most commonly used methods for separation in biology and chemistry. However, effective fractionation is not always easy to obtain, as preparative centrifuge experiments are mostly conducted in an empirical way, even when it is guided by the quantitative results from analytical ultracentrifuge (AUC). Very few works have been performed to enhance the fractionation resolution of the differential centrifugation method in a swing-out rotor.

Solvent-pair surfactants enabled assembly of clusters and copolymers towards programmed mesoporous metal oxides.

Organic-inorganic molecular assembly has led to numerous nano/mesostructured materials with fantastic properties, but it is dependent on and limited to the direct interaction between host organic structure-directing molecules and guest inorganic species. Here, we report a "solvent-pair surfactants" enabled assembly (SPEA) method to achieve a general synthesis of mesostructured materials requiring no direct host-guest interaction. Taking the synthesis of mesoporous metal oxides as an example, the dimethylformamide/water solvent pairs behave as surfactants and induce the formation of mesostructured polyoxometalates/copolymers nanocomposites, which can be converted into metal oxides.

Miniature line-scanned dual-axis confocal microscope for versatile clinical use.

A miniature optical-sectioning fluorescence microscope with high sensitivity and resolution would enable non-invasive and real-time tissue inspection, with potential use cases including early disease detection and intraoperative guidance. Previously, we developed a miniature MEMS-based dual-axis confocal (DAC) microscope that enabled video-rate optically sectioned microscopy of human tissues. However, the device's clinical utility was limited due to a small field of view, a non-adjustable working distance, and a lack of a sterilization strategy.

Structural Transformation between a Nematic Loose Packing and a Randomly Stacked Close Packing of Granular Disks.

Packing structures of granular disks are reconstructed using magnetic resonance imaging techniques. As packing fraction increases, the packing structure transforms from a nematic loose packing to a dense packing with randomly oriented stacks. According to our model based on Edwards' volume ensemble, stack structures are statistically favored when the effective temperature decreases, which has a lower structural anisotropy than single disks, and brings down the global orientational order consequently.

4d Lithium-Rich Cathode System Reinvestigated with Electron Paramagnetic Resonance: Correlation between Ionicity, Oxygen Dimers, and Molecular O.

Layered lithium-rich (Li-rich) oxide cathodes with additional capacity contribution via oxygen redox are promising high energy density cathodes for next generation Li-ion batteries. However, the chemical states of the oxidized oxygen in charged materials are under fierce debate, including the O with stable electron holes, O-O dimer (O) ( > 0), molecular O, and oxygen π redox. Here, we show using electron paramagnetic resonance (EPR) spectroscopy that in the 4d Li-rich ruthenate compounds, LiRuSnO and LiRuSnO, strong covalency between 4d transition metal and oxygen can inhibit the formation of trapped molecular O but not suppress the formation of O-O dimer.

"Win-Win" Modification of LiCoO Enables Stable and Long-Life Cycling of Sulfide-Based All Solid-State Batteries.

Interfacial side reactions and space charge layers between the oxide cathode material and the sulfide solid-state electrolytes (SSEs), along with the structural degradation of the active material, significantly compromise the electrochemical performance of all-solid-state batteries (ASSLBs). Surface coating and bulk doping of the cathodes are considered the most effective approaches to mitigate the interface issues between the cathode and SSEs and enhance the structural integrity of composite cathodes. Here, a one-step low-cost means is ingeniously designed to modify LiCoO (LCO) with heterogeneous Li TiO /Li(TiMg) O surface coating and bulk gradient Mg doping.

Mitigating the Formation of Tetrahedral Zn in Layered Oxides Enables Reversible Lattice Oxygen Redox Triggering by the Na-O-Zn Configuration.

Na-ion layered oxides with Na-O-A' local configurations (A' represents nonredox active cations such as Li, Na, Mg, Zn) are attractive cathode choices for energy-dense Na-ion batteries owing to the accumulation of cationic and anionic redox activities. However, the migration of A' would degrade the stability of the Na-O-A' configuration, bringing about drastic capacity decay and local structural distortions upon cycling. Herein, we uncover the close interplay between irreversible Zn migration and the inactivation of lattice oxygen redox (LOR) for layered oxides based on Na-O-Zn configuration by Na solid-state NMR and Zn K-edge EXAFS techniques.

Probing the degradation of LiCoO in batteries subjected to high-voltage cycling with O solid-state NMR spectroscopy.

The long-term cycling stability of LiCoO under high-voltage operation in lithium-ion batteries is still not satisfactory and the mechanism of capacity decay is not well understood. Here we mainly apply O MAS NMR spectroscopy to probe the phase transformation of cycled LiCoO cathodes in both liquid cells and solid cells. It turns out that deterioration into the spinel phase is the main cause.

Achieving Long-Enduring High-Voltage Oxygen Redox in P2-Structured Layered Oxide Cathodes by Eliminating Nonlattice Oxygen Redox.

Triggering reversible lattice oxygen redox (LOR) in oxide cathodes is a paradigmatic approach to overcome the capacity ceiling determined by orthodox transition-metal (TM) redox. However, the LOR reactions in P2-structured Na-layered oxides are commonly accompanied by irreversible nonlattice oxygen redox (non-LOR) and large local structural rearrangements, bringing about capacity/voltage fading and constantly evolving charge/discharge voltage curves. Herein, a novel Na Mg Ti Mn ◻ O (◻ = TM vacancies) cathode with both NaOMg and NaO◻ local configurations is deliberately designed.

All-Solid-State Batteries with Pre-plated Ultrathin Lithium Metal Enabled by No Pressure Holding and Characterized by Electron Paramagnetic Resonance Imaging.

All-solid-state batteries with ultrathin lithium metal, close to the anode-free solid-state batteries, could achieve high energy density. However, it is not trivial to plate an ultrathin lithium metal layer on a Cu current collector (Cu-CC). electron paramagnetic resonance (EPR) imaging showed that the pre-plating on Cu-CC in a Li-In|LiPSCl|Cu cell without pressure holding produced a lithium metal layer with a small area.

Measuring relaxation in paramagnetic solids with solid-state NMR: a case study on the milling induced phase transition in LiCoO.

Solid-state NMR has been a vital tool for the study of structural evolution of cathodes in lithium-ion and sodium-ion batteries. However, the differentiation of relaxation parameters for certain sites is difficult owing to limited spectral resolution associated with strong anisotropic hyperfine interaction. Here we propose a novel IR-pjMATPASS method that can measure relaxation with site-specific resolution for paramagnetic solids.

Highly Reversible Local Structural Transformation Enabled by Native Vacancies in O2-Type Li-Rich Layered Oxides with Anion Redox Activity.

A novel O2-phase LiNi[□Mn]O cathode with native vacancies (denoted as "□") was delicately designed. By a combination of noninvasive Li pj-MATPASS NMR and electron paramagnetic resonance measurements, it is unequivocally shown that the reservation of native vacancies enables the fully reversible local structural transformation without the formation of Li in the Li layer (Li) in LiNi[□Mn]O during the initial and subsequent cycling. In addition, the pernicious in-plane Mn migration that would result in the generation of trapped molecular O is effectively mitigated in LiNi[□Mn]O.

Unraveling the Strong Fluorescence Enhancement of HPBI Molecules by ZIF-8 Colloidal Suspensions via Adsorption Analysis.

Enhancing the fluorescence of organic dye by colloidal particles is one of the most promising routes to optimize fluorescence detection. However, in addition to metallic particles, which serve as the most frequently used particles and have been found to employ the plasmonic resonance to provide strong fluorescence enhancement, neither new types of colloidal particles nor new fluorescence mechanisms have been intensively explored in recent years. In this work, strongly enhanced fluorescence was observed when 2-(2-hydroxyphenyl)-1-benzimidazole (HPBI) molecules were simply mixed with zeolitic imidazolate framework-8 (ZIF-8) colloidal suspensions.

Oxygen Redox Activation at Initial Cycle to Improve Cycling Stability for the NaLiNiMnO System.

Oxygen reactions are commonly used to increase the specific capacities of Na-ion batteries, especially for the NaLiTMO systems. Previous research focused on improving the stabilities of oxygen reactions to enhance cycling stability. However, the effects of oxygen reactions on the distribution of Li ions in the transition metal (TM) and alkali metal (AM) layers for the Na-ion battery are relatively unexplored and rarely employed.

Completely Eradicating Singlet Oxygen in Li-O Battery via Cobalt(II)-Porphyrin Complex-Catalyzed LiOH Chemistry.

Li-O batteries have an extremely high theoretical specific energy; however, the large charge overpotential and highly reactive singlet oxygen (O) are two major obstacles. Porphyrin as a special kind of macrocyclic conjugated aromatic system exhibits excellent redox activity, which can be optimized by introducing a center metal atom. Herein, 5,10,15,20-tetrakis(4-aminophenyl)-porphyrin (TAPP) and 5,10,15,20-tetrakis(4-aminophenyl)-porphyrin-Co(II) (Co-TAP) are applied as effective redox mediators for Li-O batteries.