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Lithium-ion batteries are still the main theme of the contemporary market. Commercial graphite has struggled to meet the demand of high energy density for various electronic products due to its low theoretical capacity. Therefore, exploring for a new anode with high capacity is important. Vanadium nitride has attracted widespread attention due to its high theoretical specific capacity and good chemical/thermal stability. However, vanadium nitride is accompanied by huge volume expansion and nanoparticle agglomeration during the electrochemical reaction, which limits its application. Herein, sea-urchin-like vanadium nitride (SUK-VN) was successfully prepared with a simple hydrothermal method combined with an annealing strategy to boost the actual capacity of the vanadium nitride. The special sea-urchin-like morphology effectively suppresses the agglomeration of vanadium nitride nanoparticles and exposes more reactive sites, which facilitates the electrochemical performance of electrode materials. In the half-cells, sea-urchin-like vanadium nitride exhibits a specific capacity of 361.5 mAh g−1 at 0.1 A g−1 after 60 cycles, and even still achieves a specific capacity of 164.5 with a Coulomb efficiency of approximately 99.9% at 1 A g−1 after 500 cycles. Such a strategy provides the potential to enhance the electrochemical properties of vanadium nitride anodes in terms of solving the nanoparticle agglomeration. [ABSTRACT FROM AUTHOR]

Abstract: Anionic redox processes are vital to realize high capacity in lithium‐rich electrodes of lithium‐ion batteries. However, the activation mechanism of these processes remains ambiguous, hampering further implementation in new electrode design. This study demonstrates that the electrochemical activity of inert cubic‐Li2TiO3 is triggered by Fe3+ substitution, to afford considerable oxygen redox activity. Coupled with first principles calculations, it is found that electron holes tend to be selectively generated on oxygen ions bonded to Fe rather than Ti. Subsequently, a thermodynamic threshold is unravelled dictated by the relative values of the Coulomb and exchange interactions (U) and charge‐transfer energy (Δ) for the anionic redox electron‐transfer process, which is further verified by extension to inactive layered Li2TiS3, in which the sulfur redox process is activated by Co substitution to form Li1.2Ti0.6Co0.2S2. This work establishes general guidance for the design of high‐capacity electrodes utilizing anionic redox processes. [ABSTRACT FROM AUTHOR]

The search for superior-energy-density electrode materials for rechargeable batteries is prompted by the continuously growing demand for new electric vehicles and large energy-storage grids. The structural properties of electrode materials affect their electrochemical performance because their functionality is correlated to their structure at the atomic scale. Although challenging, a deeper and comprehensive understanding of the basic structural operating units of electrode materials may contribute to the advancement of new energy-storage technologies and many other technologies. Therefore, we must strategically control both the structure and kinetics of electrode materials to achieve optimal electrochemical performance. In this contribution, advancements in synchrotron radiation techniques, specifically in situ/operando experiments on electrode materials for rechargeable batteries, are presented and discussed. Indeed, the latest synchrotron radiation methods offer deeper insights into pristine and chemically modified electrode materials, opening new opportunities to optimize these materials and exploit new technologies. In particular, the most recent results from in situ/operando synchrotron radiation measurements, which play a critical role in the fundamental understanding of the kinetics processes that occur in rechargeable batteries, are discussed. [ABSTRACT FROM AUTHOR]

Lithium-rich manganese-based layered oxides show great potential as high-capacity cathode materials for lithium ion batteries, but usually exhibit a poor cycle life, gradual voltage drop during cycling, and low thermal stability in the highly delithiated state. Herein, a strategy to promote the electrochemical performance of this material by manipulating the electronic structure through incorporation of boracic polyanions is developed. As-prepared Li[Li0.2Ni0.13Co0.13Mn0.54](BO4)0.015(BO3)0.005O1.925 shows a decreased M-O covalency and a lowered O 2p band top compared with pristine Li[Li0.2Ni0.13Co0.13Mn0.54]O2. As a result, the modified cathode exhibits a superior reversible capacity of 300 mA h g−1 after 80 cycles, excellent cycling stability with a capacity retention of 89% within 300 cycles, higher thermal stability, and enhanced redox couple potentials. The improvements are correlated to the enhanced oxygen stability that originates from the tuned electronic structure. This facile strategy may further be extended to other high capacity electrode systems. [ABSTRACT FROM AUTHOR]

A novel temperature-dependent electrochemical system has been designed for in-operando time-resolved X-ray diffraction (XRD) study with laboratory X-ray sources. Meanwhile, a dedicated in-situ XRD battery cell has been designed for the in-situ XRD characterization of standard coin cell batteries. Thanks to a shaped Be window, the detection-angle of this in-operando system covers a wide range from 4° to 160° XRD patterns can be collected over the wide temperature range, -30 °C to 100 °C. To test the device, LiMn 2 O 4 and LiFePO 4 electrode materials are measured and in-operando XRD data are collected in electrochemical processes at low and high temperatures. This in-operando system enables original in-operando investigations on the electrode structural evolution of batteries vs. temperature, allowing a deeper understanding of the structural evolution of electrode materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Peroxide structure O 2 n− has proven to appear after electrochemical process in many lithium-excess precious metal oxides, representing extra reversible capacity. We hereby report construction of a Li-excess rock-salt oxide Li 1+x Ni 1/2-3x/2 Ru 1/2+x/2 O 2 electrode, with cost effective and eco-friendly 3d transition metal Ni partially substituting precious 4d transition metal Ru. It can be seen that O 2 n− is formed in pristine Li 1.23 Ni 0.155 Ru 0.615 O 2 , and stably exists in subsequent cycles, enabling discharge capacities to 295.3 and 198 mAh g −1 at the 1st/50th cycle, respectively. Combing ex-situ X-ray absorption near edge spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, high resolution transmission electron microscopy and electrochemical characterization, we demonstrate that the excellent electrochemical performance comes from both percolation network with disordered structure and cation/anion redox couples occurring in charge-discharge process. Li-excess and substitution of common element have been demonstrated to be a breakthrough for designing novel high performance commercial cathodes in rechargeable lithium ion battery field. [ABSTRACT FROM AUTHOR]

Herein, a novel in-situ X-ray computed tomography (CT) imaging apparatus with stack pressures is proposed to detect the micro-structural evolution at the interface during the electrochemical process. And the relationship between the electrochemical performance and the interface morphology of lithium metal batteries has been effectively investigated through this in-situ technology. It can be observed that the growth of Li dendrites and their morphology evolution are directly dependent on the stack pressures. The Li dendrite grows from the needle-structure to the island-structure, accompanied by the tip-growth mode transferring to the base-growth mode in the range of the critical pressure. Moreover, the growth of Li dendrites can also be effectively inhibited when loading a suitable stack pressure. This novel in-situ CT imaging technology provides a feasible way to underlying the interface micro-structure evolution, electrochemical-pressure complexions, and safety of next-generation rechargeable batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) nanoarchitectures can improve the performance of electrical energy storage systems. In this paper, combining an improved solvothermal method with calcination treatment, thin layer carbon-coated MoO 2 nanoparticles with the size of 20-50 nm were uniformly dispersed in 3D graphene aerogel (abbreviated as MoO 2 @C-Gas). The hybrid materials were subsequently used as a new-structured anode for lithium-ion batteries (LIBs), yielding high reversible capacity with excellent stable cyclability. We found that the battery with MoO 2 @C-Gas electrode could deliver a discharge capacity of 1515 mAh g −1 at a current density of 80 mA g −1 in the first cycle, and remain at 1113 mAh g −1 over 60 cycles. Furthermore, with the increase of current density, it also exhibited a high rate of capability and good cycling performance. The outstanding performance of the hybrid electrode were attributed to the unique 3D aerogel morphology and the close combination between C@MoO 2 and graphene layers, which could significantly improve the anode's electronic conductivity. [ABSTRACT FROM AUTHOR]