Summary Lithium‐ion batteries (LIBs) have been widely used for powering electric vehicles (EVs), however, the charging time of LIBs is considerably higher than the refueling time of petrol‐fueled vehicles, which limits the applications of LIBs. Materials that can overcome this limitation should be developed, and these materials should be inexpensive to commercialize. In this study, activated carbon (AC) was used as an anode material in LIB to satisfy both the requirements. The surface and pore structure of commercial AC was suitably modified for fast charging using physical and chemical activation methods, that is, P‐AC and C‐AC, respectively. We focused on the stability of various kinds of electrode materials, such as AC, C‐AC, P‐AC, commercial graphite, and graphene, under fast‐charging conditions. Among these methods, P‐AC exhibited the most stable and highest capacity during 500 cycles at the 5C rate, although the initial capacity (<50 cycles) of P‐AC was given the second priority. We believe that the suitable mixture of meso‐ and micropores in P‐ACs increases the diffusivity and insertion rate of the Li‐ion (solvation) at fast‐charging condition, thereby leading to higher long‐term stability.

Summary Applications utilizing Li‐ion batteries (LIBs) have recently been broadened from portable electronic devices to electric vehicles. Graphite has been applied as an anode material for commercialized LIBs; however, there is a growing demand for application‐oriented LIBs with higher energy and power densities, and faster charging, compared with its limited electrochemical properties. Heteroatom‐doped graphene has been considered as a potential alternative to graphite, although its synthesis is complex and costly. In this study, we introduced a facile strategy to realize advanced anode materials through fine control of the sheet size and oxygen‐containing functional groups on the surface of graphene oxide (GO) as a raw material for heteroatom‐doped graphene. The sheet size of GO is inversely proportional to the amount of oxidizing agent, which affects the formation of various types of oxygen‐containing functional groups at the edges of GO. Mild annealing of GO selectively removes the functional groups with weak binding strength, leading to the formation of GO maximized with carbonyl groups, which can interact with Li ions quickly and reversibly. The GO with the average sheet size of 500 nm developed in this study exhibits capacities of up to 779 and 220 mAh g−1 at 0.1 and 2 A g−1, respectively. Therefore, decreasing the sheet size of GO with mild‐temperature annealing increases the number of carbonyl groups formed on the additional exposed edge of the sheets, resulting in facile Li‐ion interaction and a higher capacity as an anode material.

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Summary Molybdenum sulfide (MoSx)‐based materials have been extensively studied as a potential alternative of low‐capacity graphite anode, owing to their remarkable capacity through intercalation and conversion reactions. However, these materials should be electrochemically activated at a low potential in first discharge and simultaneously degrade, owing to their inert basal plane and unstable sulfur configuration, respectively, leading to unexpectedly low performance. Hence, it is necessary to apply sulfur‐enriched crystalline Mo3S13 clusters as an anode material to increase the number of active sites and energy densities. Unlike MoS2 possessing only terminal sulfur, Mo3S13 clusters have higher sulfur content with various and stable configuration in their structure, which can act as additional active sulfur sites. To realize an electrode with high energy density, we used the Mo3S13 clusters without any carbon supports as active materials. In the electrode preparation, we confirmed that employing poly(acrylic acid) and isopropyl alcohol as a binder and solvent, respectively, was appropriate for retaining the cluster crystallinity, resulting in the enhanced cycling stability. The Mo3S13 cluster‐based electrode as a carbon‐free electrode exhibited capacity of 1192 mAh g−1 at 0.1 A g−1 and good C‐rate capability. The significant capacity variation with the selective removal of sulfur configuration in Mo3S13 clusters indicates that the increased sulfur contents were provided as additional sources for (de)lithiation.