Keywords: Li-ion batteries, intercalation cathodes, disordered rock salt, Li 2 VO 2 F Advanced cathode materials with superior energy storage capability are highly demanded for mobile and stationary applications. The inherent structural feature of Li + hosts is critical for the battery performance. High-capacity conversion cathode materials often encounter large voltage hysteresis (low energy efficiency) accompanied with the structural reconstruction.[1]The current commercial cathode materials are still dominated by intercalation materials with intrinsic structural integrity for accommodating Li + .[2] However, the known intercalation materials have limited theoretical capacity (< 300 mAh g -1 ). [3] In addition, structural transition/degradation have often been observed for the common intercalation hosts with ordered Li + / transition metal (TM) lattice sites. Antisite disorder (Li + sites/layers occupied by TM ions) in olivines can block the one-dimensional Li + diffusion path.[4] The activation barrier for Li + diffusion in layered oxides is sensitive to the Li-content, the spacing of the

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Mixed-anion materials for Li-ion batteries have been attracting attention in view of their tunable electrochemical properties. Herein, we compare two isostructural (Fm3̅m) model intercalation materials Li2VO3 and Li2VO2F with O(2-) and mixed O(2-)/F(-) anions, respectively. Synchrotron X-ray diffraction and pair distribution function data confirm large structural similarity over long-range and at the atomic scale for these materials. However, they show distinct electrochemical properties and kinetic behaviour arising from the different anion environments and the consequent difference in cationic electrostatic repulsion. In comparison with Li2VO3 with an active V(4+/5+) redox reaction, the material Li2VO2F with oxofluoro anions and the partial activity of V(3+/5+) redox reaction favor higher theoretical capacity (460 mA h g(-1)vs. 230 mA h g(-1)), higher voltage (2.5 V vs. 2.2 V), lower polarization (0.1 V vs. 0.3 V) and faster Li(+) chemical diffusion (∼10(-9) cm(2) s(-1)vs. ∼10(-11) cm(2) s(-1)). This work not only provides insights into the understanding of anion chemistry, but also suggests the rational design of new mixed-anion battery materials.

PurposeThis study aimed to investigate the mid- to long-term outcomes of cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) for the treatment of 1-level or 2-level symptomatic cervical disc disease.MethodsMedline, Embase, and the Cochrane Central Register of Controlled Trials databases were searched to identify relevant randomized controlled trials that reported mid- to long-term outcomes (at least 48 months) of CDA versus ACDF. All data were analyzed by Review Manager 5.3 software. The relative risk (RR) and 95% confidence intervals (CIs) were calculated for dichotomous variables. The weighted mean difference (WMD) and 95%CIs were calculated for continuous variables. A random effect model was used for heterogeneous data; otherwise, a fixed effect model was used.ResultsEight prospective randomized controlled trials (RCTs) were retrieved in this meta-analysis, including 1317 and 1051 patients in CDA and ACDF groups, respectively. Patients after an ACDF had a significantly lower rate of follow-up than that after CDA. Pooled analysis showed patients in CDA group achieved significantly higher rates of overall success, Neck Disability Index (NDI) success, neurological success and significantly lower rates of implant/surgery-related serious adverse events and secondary procedure compared with that in ACDF group. The long-term functional outcomes (NDI, Visual Analog Scale (VAS) neck and arm pain scores, the Short Form 36 Health Survey physical component score (SF-36 PCS)), patient satisfaction and recommendation, and the incidence of superior adjacent segment degeneration also favored patients in CDA group with statistical difference. Regarding inferior adjacent segment degeneration, patients in CDA group had a lower rate without statistical significance.ConclusionsThis meta-analysis showed that cervical disc arthroplasty was superior over anterior discectomy and fusion for the treatment of symptomatic cervical disc disease in terms of overall success, NDI success, neurological success, implant/surgery-related serious adverse events, secondary procedure, functional outcomes, patient satisfaction and recommendation, and superior adjacent segment degeneration.

New high‐capacity intercalation cathodes of Li2VxCr1−xO2F with a stable disordered rock salt host framework allow a high operating voltage up to 3.5 V, good rate performance (960 Wh kg−1 at ≈1 C), and cycling stability.

In this work, LiMnTiO4 (a structural analogue of classic spinel LiMn2O4) with a disordered cubic spinel structure (Fd3̅m) has been synthesized by a low-temperature sol–gel route. The as-obtained LiMnTiO4 exhibits excellent cycling stability in a wide voltage range from 1.5 to 4.8 V with high discharge capacities of 290, 250, and 140 mA h g–1 at a C/40, C/19, and 1C rate, respectively. Combined long- and short-range structural characterization techniques are used to reveal the correlation between structure and electrochemical behavior. During cycling, the charge/discharge profiles of LiMnTiO4 evolve from initially two well-separated plateaus into sloping regimes. In the early stage of discharge, LiMnTiO4 undergoes phase transitions from an initial spinel phase to mixtures of predominant rock-salt (Fm3̅m) and tetragonal (I41/amd) structures along with a decrease in crystallite size from 12 nm to 3 to 4 nm. During further cycling, the spinel/rock-salt phase transition was found to be reversible with the cubic framework remaining intact. The presence of the tetragonal phase after the first discharge suggests that the Mn3+ Jahn–Teller distortion is partially involved during lithiation from Li1–y Mn3+y TiO4 to Li1+x Mn3–x TiO4 and the fraction of such a tetragonal phase remains at about 30–40% during subsequent cycling.

The mesospheric response to the 2002 Antarctic Stratospheric Sudden Warming (SSW) is analysed using the Canadian Middle Atmosphere Model Data Assimilation System (CMAM‐DAS), where it represents a vertical propagation of information from the observations into the data‐free mesosphere. The CMAM‐DAS simulates a cooling in the lowest part of the mesosphere which is accomplished by resolved motions, but which is extended to the mid‐ to upper mesosphere by the response of the model's non‐orographic gravity‐wave drag parameterization to the change in zonal winds. The basic mechanism is that elucidated by Holton consisting of a net eastward wave‐drag anomaly in the mesosphere during the SSW, although in this case there is a net upwelling in the polar mesosphere. Since the zonal‐mean mesospheric response is shown to be predictable, this demonstrates that variations in the mesospheric state can be slaved to the lower atmosphere through gravity‐wave drag.