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The demand for electrochemical energy storage is increasing rapidly due to a combination of decreasing costs in renewable electricity, governmental policies promoting electrification, and a desire by the public to decrease CO2 emissions. Lithium‐ion batteries are the leading form of electrochemical energy storage for electric vehicles and the electrical grid. Lithium‐ion cell anodes are mostly made of graphite, which is derived from geographically constrained, non‐renewable resources using energy‐intensive and highly polluting processes. Thus, there is a desire to innovate technologies that utilize abundant, affordable, and renewable carbonaceous materials for the sustainable production of graphite anodes under relatively mild process conditions. This review highlights novel attempts to realize the aforementioned benefits through innovative technologies that convert biocarbon resources, including lignocellulose, into high quality graphite for use in lithium‐ion anodes. [ABSTRACT FROM AUTHOR]

Graphene‐based materials have been extensively researched as a means improve the electrochemical performance of transition metal oxides in Li‐ion battery applications, however an understanding of the effect of the different synthesis routes, and the factors underlying the oft‐stated better performance of the hybrid materials (compared to the pure metal oxides) is not always demonstrated. For the first time, we report a range of synthetic routes to produce graphene oxide (GO)‐coated CuO, micro‐particle/GO "bundles" as well as nano‐particulates decorated on GO sheets to enable a comparison with CuO and its carbon‐coated analogue, as confirmed using scanning electron microscopy (SEM) imaging and Raman spectroscopy. Cyclic voltammetry was utilized to probe the lithiation/delithiation mechanism of CuO by scanning at successively decreasing vertex potentials, uncovering the importance of a full reduction to Cu metal on the reduction step. The GO hybrid materials clearly show enhanced specific capacities and cycling stabilities comparative to the CuO, with the most promising material achieving a capacity of 746 mAh g−1 and capacity retention of 92 % after 30 cycles, which is the highest stable capacity quoted in literature for CuO. The simple cyclic voltammetry technique used in this work could be implemented to help further understand any conversion‐type anode materials, in turn accelerating the research and industrial development of conversion anodes. [ABSTRACT FROM AUTHOR]

The transformation of MXene sheets into TiOF2 2D sheets with superior electrochemical performance was developed. MXene synthesized from Ti3AlC2 was fluorinated for 3, 6, and 24 h, respectively, by means of a direct fluorination process. Exposure of MXene powder to elemental fluorine for 3 h induced the formation of CF2 groups and TiF3 on the surface, which have beneficial effects on the electrochemical performance. X‐ray photoelectron spectroscopy suggested that after fluorinating the MXene sample for 6 h Ti2+ and Ti3+ were not present on the surface but only Ti4+, indicating the formation of TiOF2. XRD indicated that TiOF2 was present after fluorinating for 3 h, and after 24 h the MXene had transformed to TiOF2 with minor impurities remaining, maintaining its 2D layer morphology. The 24 h fluorinated sample with its TiOF2 phase showed superior capacity that increased with cycle number. It also had a better rate capability than non‐2D‐layered TiOF2, indicating the advantage of the 2D‐layered morphology derived from the parent MXene phase. 2D makes the difference: MXene fluorinated by means of a direct fluorination process for 24 h is transformed into TiOF2 sheets, maintaining the 2D layer morphology. This material exhibits superior electrochemical performance such as increased capacity, high rate capability, and long cycling stability for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: We report a new Li–S cell concept based on an optimized F‐free catholyte solution and a high loading nanostructured C/S composite cathode. The Li2S8 present in the electrolyte ensures both buffering against active material dissolution and Li+ conduction. The high S loading is obtained by confining elemental S (≈80 %) in the pores of a highly ordered mesopores carbon (CMK3). With this concept we demonstrate stabilization of a high energy density and excellent cycling performance over 500 cycles. This Li–S cell has a specific capacity that reaches over 1000 mA h g−1, with an overall S loading of 3.6 mg cm−2 and low electrolyte volume (i.e., 10 μL cm−2), resulting in a practical energy density of 365 Wh kg−1. The Li–S system proposed thus meets the requirements for large scale energy storage systems and is expected to be environmentally friendly and have lower cost compared with the commercial Li‐ion battery thanks to the removal of both Co and F from the overall formulation. [ABSTRACT FROM AUTHOR]

Li and Mn-rich layered oxides with the general structure x Li2MnO3⋅(1- x) LiMO2 (M=Ni, Mn, Co) are promising cathode materials for Li-ion batteries because of their high specific capacity, which may be greater than 250 mA h g−1. However, these materials suffer from high first-cycle irreversible capacity, gradual capacity fading, limited rate capability and discharge voltage decay upon cycling, which prevent their commercialization. The decrease in average discharge voltage is a major issue, which is ascribed to a structural layered-to-spinel transformation upon cycling of these oxide cathodes in wide potential ranges with an upper limit higher than 4.5 V and a lower limit below 3 V versus Li. By using four elements systems (Li, Mn, Ni, O) with appropriate stoichiometry, it is possible to prepare high capacity composite cathode materials that contain LiMn1.5Ni0.5O4 and Li xMn yNi zO2 components. The Li and Mn-rich layered-spinel cathode materials studied herein exhibit a high specific capacity (≥200 mA h g−1) with good capacity retention upon cycling in a wide potential domain (2.4-4.9 V). The effect of constituent phases on their electrochemical performance, such as specific capacity, cycling stability, average discharge voltage, and rate capability, are explored here. This family of materials can provide high specific capacity, high rate capability, and promising cycle life. Using Co-free cathode materials is also an obvious advantage of these systems. [ABSTRACT FROM AUTHOR]

A new olivine composition (i.e., LiFe0.25Mn0.5Co0.25PO4) is proposed as electrode material with increased energy density for application in lithium-ion batteries. The new formulation increases the working voltage and induces different electrochemical behavior with respect to bare olivine materials based on Fe. The study provides deep insight into the features of the Fe3+/Fe2+, Mn3+/Mn2+, and Co3+/Co2+ redox couples within the olivine lattice in terms of electrochemical activity, Li+ transport properties, and Li-cell behavior. The electrochemical characterization clearly reveals the voltage signatures corresponding to the various metals; however, the Mn3+/Mn2+ process has higher intrinsic polarization with respect to Fe3+/Fe2+ and Co3+/Co2+. This issue is efficiently mitigated by carbon coating the material, resulting in enhanced electrochemical performances. [ABSTRACT FROM AUTHOR]

Front Cover: Utilizing Cyclic Voltammetry to Understand the Energy Storage Mechanisms for Copper Oxide and its Graphene Oxide Hybrids as Lithium-Ion Battery Anodes (ChemSusChem 6/2020) Keywords: anode materials; graphene; lithium-ion; metal oxide; cyclic voltammetry EN anode materials graphene lithium-ion metal oxide cyclic voltammetry 1044 1044 1 03/27/20 20200320 NES 200320 B The Front Cover b shows bees building a graphene-containing battery that powers an external circuit, depicted by a purple curve. Anode materials, graphene, lithium-ion, metal oxide, cyclic voltammetry. [Extracted from the article]

The transformation of MXene sheets into TiOF 2 2D sheets with superior electrochemical performance was developed. MXene synthesized from Ti 3 AlC 2 was fluorinated for 3, 6, and 24 h, respectively, by means of a direct fluorination process. Exposure of MXene powder to elemental fluorine for 3 h induced the formation of CF 2 groups and TiF 3 on the surface, which have beneficial effects on the electrochemical performance. X-ray photoelectron spectroscopy suggested that after fluorinating the MXene sample for 6 h Ti 2+ and Ti 3+ were not present on the surface but only Ti 4+ , indicating the formation of TiOF 2 . XRD indicated that TiOF 2 was present after fluorinating for 3 h, and after 24 h the MXene had transformed to TiOF 2 with minor impurities remaining, maintaining its 2D layer morphology. The 24 h fluorinated sample with its TiOF 2 phase showed superior capacity that increased with cycle number. It also had a better rate capability than non-2D-layered TiOF 2 , indicating the advantage of the 2D-layered morphology derived from the parent MXene phase., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)