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Lithium metal, with its high theoretical capacity and low redox potential, is the most promising next‐generation high‐energy‐density battery anode material. However, the formation of uneven surface layers and dead lithium, significant volume changes in the electrode, and dendrite growth lead to rapid capacity degradation, low cycling stability, and safety issues, limiting the commercialization of lithium metal batteries (LMBs). As a strategy to improve the stability of LMBs, introducinga three‐dimensional (3D) structure with a large surface area can accommodate lithium (Li) inside the structure and homogenize local current density. Also, as a current collector and host material, free‐standing carbon materials, with the advantages of lightness, low cost, electrochemical and mechanical stability, and excellent electronic conductivity, can effectively enhance energy density and cycle performance. In this review, we first discuss the chemical properties of carbon, and then summarize recent research progress related to the 3D structuring and chemical modification of carbon materials as a Li metal host. Finally, we present perspectives on future research for the practical application of free‐standing carbon materials for LMBs. [ABSTRACT FROM AUTHOR]

Small coin cell batteries are predominantly used for testing lithium‐ion batteries (LIBs) in academia because they require small amounts of material and are easy to assemble. However, insufficient attention is given to difference in cell performance that arises from the differences in format between coin cells used by academic researchers and pouch or cylindrical cells which are used in industry. In this article, we compare coin cells and pouch cells of different size with exactly the same electrode materials, electrolyte, and electrochemical conditions. We show the battery impedance changes substantially depending on the cell format using techniques including Electrochemical Impedance Spectroscopy (EIS) and Galvanostatic Intermittent Titration Technique (GITT). Using full cell NCA‐graphite LIBs, we demonstrate that this difference in impedance has important knock‐on effects on the battery rate performance due to ohmic polarization and the battery life time due to Li metal plating on the anode. We hope this work will help researchers getting a better idea of how small coin cell formats impact the cell performance and help predicting improvements that can be achieved by implementing larger cell formats. [ABSTRACT FROM AUTHOR]

We demonstrate a unique synthetic route for oxygen-deficient mesoporous TiO x by a redox-transmetalation process by using Zn metal as the reducing agent. The as-obtained materials have significantly enhanced electronic conductivity; 20 times higher than that of as-synthesized TiO2 material. Moreover, electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) measurements are performed to validate the low charge carrier resistance of the oxygen-deficient TiO x. The resulting oxygen-deficient TiO x battery anode exhibits a high reversible capacity (∼180 mA h g−1 at a discharge/charge rate of 1 C/1 C after 400 cycles) and an excellent rate capability (∼90 mA h g−1 even at a rate of 10 C). Also, the full cell, which is coupled with a LiCoO2 cathode material, exhibits an outstanding rate capability (>75 mA h g−1 at a rate of 3.0 C) and maintains a reversible capacity of over 100 mA h g−1 at a discharge/charge of 1 C/1 C for 300 cycles. [ABSTRACT FROM AUTHOR]

Carbon nanofibers decorated with various metal oxide nanoparticles were fabricated by combining an electrospinning technique of bicomponent polymer mixture and a sol-gel reaction and subsequent carbonization process. Electrospun polymer nanofibers consisting of polyacrylonitrile (PAN) and poly(vinyl pyrrolidone) (PVP) with controllable diameters were fabricated with PAN/PVP core/shell types via phase-separation due to the immiscibility between two polymers. The electrospun nanofibers served as supporting materials with binding sites of PVP to incorporate titanium oxide precursor. Subsequently, the carbonization of the fibers led to the formation of carbon nanofibers@TiO2 for energy application, in which rutile TiO2 nanoparticles were decorated on the surface of carbon nanofiber. Especially, this TiO2 decorated carbon nanofiber electrode exhibited excellent electrochemical property in lithium-ion batteries (≈600 mA h g−1 at C/5 rate for 100 cycles). Furthermore, the carbon nanofibers were also successfully modified with other metal oxides, including NiO, SnO2, and ZrO2 nanoparticles, in a similar manner. [ABSTRACT FROM AUTHOR]

To be a thinner and more lightweight lithium‐ion battery with high energy density, the next‐generation anode with high gravimetric and volumetric capacity is a prerequisite. In this regard, utilizing high silicon (3579 mAh g−1) content in the electrode for the anode has been highlighted as a practically relevant approach. However, there still remains a crucial issue related to intrinsic volume expansion (>300%) of silicon upon lithiation, which can directly affect severe electrode swelling as well as accelerate its capacity fading by triggering structural degradation and electrical contact loss between particles. Herein, macropore‐exploited design, which can accommodate the volume change of high silicon content within the extended pore of graphite upon repeated cycling, is introduced. Such unique macropore‐exploited design leads to much less electrode swelling, by preserving its morphological integrity and contact between particles, than that of the comparative group with different sized pore and silicon distribution. As a result, this anode (914 mAh g−1) demonstrates notable gravimetric (220 Wh kg−1 at 6000 W kg−1) and volumetric energy density (623 Wh L−1 upon full lithiation after 100 cycles), exceeding that of a nano‐silicon blended graphite anode (127 Wh kg−1 and 229 Wh L−1) in the full‐cell system. [ABSTRACT FROM AUTHOR]

Replacing noble-metal-based oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is the key to developing efficient Zn-air batteries (ZABs). Here, a homogeneous ternary Ni 46 Co 40 Fe 14 nanoalloy with a size distribution of 30-60 nm dispersed in a carbon matrix (denoted as C@NCF-900) as a highly efficient bifunctional electrocatalyst produced via supercritical reaction and subsequent heat treatment at 900 °C is reported. Among all the transition-metal-based electrocatalysts, the C@NCF-900 exhibits the highest ORR performance in terms of half-wave potential (0.93 V) in 0.1 m KOH. Moreover, C@NCF-900 exhibits negligible activity decay after 10 000 voltage cycles with minor reduction (0.006 V). In ZABs, C@NCF-900 outperforms the mixture of Pt/C 20 wt% and IrO 2 , cycled over 100 h under 58% depth of discharge condition. Furthermore, density functional theory (DFT) calculations and in situ X-ray absorption spectroscopy strongly support the active sites and site-selective reaction as a plausible ORR/OER mechanism of C@NCF-900., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We demonstrate a unique synthetic route for oxygen-deficient mesoporous TiO x by a redox-transmetalation process by using Zn metal as the reducing agent. The as-obtained materials have significantly enhanced electronic conductivity; 20 times higher than that of as-synthesized TiO 2 material. Moreover, electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) measurements are performed to validate the low charge carrier resistance of the oxygen-deficient TiO x . The resulting oxygen-deficient TiO x battery anode exhibits a high reversible capacity (∼180 mA h g -1 at a discharge/charge rate of 1 C/1 C after 400 cycles) and an excellent rate capability (∼90 mA h g -1 even at a rate of 10 C). Also, the full cell, which is coupled with a LiCoO 2 cathode material, exhibits an outstanding rate capability (>75 mA h g -1 at a rate of 3.0 C) and maintains a reversible capacity of over 100 mA h g -1 at a discharge/charge of 1 C/1 C for 300 cycles., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)