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The interfacial origin of performance improvement and fade of high-voltage cathodes of LiNi 0.5 Co 0.2 Mn 0.3 O 2 for high-energy lithium-ion batteries has been investigated. Performance improvement was achieved through interfacial stabilization using 5 wt % methyl (2,2,2-trifluoroethyl) carbonate (FEMC) of fluorinated linear carbonate as a new electrolyte additive. Cycling with the FEMC additive at 3.0−4.6 V versus Li/Li + results in the formation of a stable solid electrolyte interface (SEI) layer and effective passivation of cathode surface, leading to improved cycling performance delivering enhanced discharge capacities to 205−182 mAhg −1 and capacity retention of 84% over 50 cycles. The SEI layer notably includes plenty of metal fluorides and −CF-containing species formed by additive decomposition. On the contrary, the origin of performance fade in electrolyte only was ineffective surface passivation and dissolution of metal elements, which leads to oxygen loss, surface structural degradation and crack formation at the LiNi 0.5 Co 0.2 Mn 0.3 O 2 particles. The data provide a basic understanding of the interfacial stabilization mechanism on high-voltage layered oxide cathodes.

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We report for the first time a promising approach to achieve the maximum capacity of LiNi0.8Co0.1Mn0.1O2 cathodes in a non-flammable electrolyte for safe and high-energy density lithium-ion and lithium metal batteries.

High-capacity Li-rich layered composite oxide, xLi 2 MnO 3 • (1-x)LiMO 2 (M = Mn, Ni, Co), is a promising candidate cathode material for high-energy electrochemical energy storage. Enabling the high-performance of high-voltage cathode relies on an electrolyte breakthrough and the solid electrolyte interface (SEI) stabilization. In this study, the 0.6Li 2 MnO 3 • 0.4LiNi 0.45 Co 0.25 Mn 0.3 O 2 (Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O 2 , LMNC) cathode is operated at 2.5-4.8 V with 5 wt% fluorinated linear carbonate, di-(2,2,2 trifluoroethyl)carbonate (DFDEC), as a high-voltage electrolyte additive, for the first time and applied to a high-energy lithium-ion battery. The cathode with DFDEC outperforms that in electrolyte only, delivering a high capacity of 250 mAhg −1 with an excellent chargedischarge cycling stability at the rate of 0.2C. Upon the use of DFDEC, the cathode surface is effectively passivated by a stable SEI composed of DFDEC decomposition products, which inhibit a detrimental metal dissolution and structural cathode degradation. A full-cell based on the SEI-stabilized LMNC cathode and graphite anode successfully demonstrates doubled energy density (∼278 Whkg −1 ) compared to ∼136 Whkg −1 of a commercialized cell of graphite//LiCoO 2 and an excellent cycling stability.

Increasing the capacity of Li‐rich layered oxide (LMNC) cathode material for high‐energy density lithium‐ion batteries relies on the increase of charge cut‐off voltage toward 5 V, under the utilization of anodically stable electrolyte component. The utilization of di‐(2,2,2 trifluoroethyl)carbonate (DFDEC)‐containing electrolyte permits significant improvement of anodic stability, cathode–electrolyte interface, and cycling stability of LMNC cathode, with respect to conventional electrolyte. In the present study, the limit of anodic stability of DFDEC under charging to 5.5 V versus Li is explored, and the interfacial processes of DFDEC‐derived surface protection mechanism are investigated, utilizing charge cut‐off voltage‐dependent surface and structural analyses. The oxidative decomposition of DFDEC is found to begin at 4.7 V, producing metal fluorides and CF‐containing organic compounds as the earliest surface species, passivating the cathode surface and reducing metal dissolution, structural transformation, and cathode degradation. The tolerable limit of charge cut‐off voltage of a model electrolyte of 0.1 m LiPF6/DFDEC is determined to be 5.0 V, to which the cathode outperforms conventional electrolyte, delivering discharge capacities of 261–225 mAhg−1 with the capacity retention of 86% at the 50th cycle. The data give an insight into the principles of electrolyte design and high‐voltage cathode–electrolyte interfacial stabilization toward advanced 5 V lithium‐ion batteries.

The effects of lithium bis(fluorosulfonyl)imide, Li[N(SO 2 F) 2 ] (LiFSI), as an additive on the low-temperature performance of graphite∥LiCoO 2 pouch cells are investigated. The cell, which includes 0.2M LiFSI salt additive in the 1M lithium hexafluorophosphate (LiPF 6)-based conventional electrolyte, outperforms the one without additive under −20 ○ C and high charge cutoff voltage of 4.3 V, delivering higher discharge capacity and promoted rate performance and cycling stability with the reduced change in interfacial resistance. Surface analysis results on the cycled LiCoO 2 cathodes and cycled graphite anodes extracted from the cells provide evidence that a LiFSI-induced improvement of highvoltage cycling stability at low temperature originates from the formation of a less resistive solid electrolyte interphase layer, which contains plenty of LiFSI-derived organic compounds mixed with inorganics that passivate and protect the surface of the cathode and anode from further electrolyte decomposition and promotes Li + ion-transport kinetics despite the low temperature, inhibiting Li metal-plating at the anode. The results demonstrate the beneficial effects of the LiFSI additive on the performance of a lithium-ion battery for use in battery-powered electric vehicles and energy storage systems in cold climates and regions.

The objectives of this study were to summarize the curriculum, history, and clinical researches of Chuna in Korea and to ultimately introduce Chuna to Western medicine. Information about the history and insurance coverage of Chuna was collected from Chuna-related institutions and papers. Data on Chuna education in all 12 Korean medicine (KM) colleges in Korea were reconstructed based on previously published papers. All available randomized controlled trials (RCTs) of Chuna in clinical research were searched using seven Korean databases and six KM journals. As a result, during the modern Chuna era, one of the three periods of Chuna, which also include the traditional Chuna era and the suppressed Chuna era, Chuna developed considerably because of a solid Korean academic system, partial insurance coverage, and the establishment of a Chuna association in Korea. All of the KM colleges offered courses on Chuna-related subjects (CRSs); however, the total number of hours dedicated to lectures on CRSs was insufficient to master Chuna completely. Overall, 17 RCTs were reviewed. Of the 14 RCTs of Chuna in musculoskeletal diseases, six reported Chuna was more effective than a control condition, and another six RCTs proposed Chuna had the same effect as a control condition. One of these 14 RCTs made the comparison impossible because of unreported statistical difference; the last RCT reported Chuna was less effective than a control condition. In addition, three RCTs of Chuna in neurological diseases reported Chuna was superior to a control condition. In conclusion, Chuna was not included in the regular curriculum in KM colleges until the modern Chuna era; Chuna became more popular as the result of it being covered by Korean insurance carriers and after the establishment of a Chuna association. Meanwhile, the currently available evidence is insufficient to characterize the effectiveness of Chuna in musculoskeletal and neurological diseases.