Carbonaceous materials have been accepted as a promising family of anode materials for lithium‐ion batteries (LIBs) owing to optimal overall performance. Among various emerging carbonaceous anode materials, hard carbons have recently gained significant attention for high‐energy LIBs. The most attractive features of hard carbons are the enriched microcrystalline structure, which not only benefits the uptake of more Li+ ions but also facilitates the Li+ ions intercalation and deintercalation. However, the booming application of hard carbons is significantly slowed by the low initial Coulombic efficiency, large initial irreversible capacity, and voltage hysteresis. Many efforts have been devoted to address these challenges toward practical applications. This paper focuses on an up‐to‐date overview of hard carbons, with an emphasis on the lithium storage fundamentals and material classification of hard carbons as well as present challenges and potential solutions. The future prospects and perspectives on hard carbons to enable practical application in next‐generation batteries are also highlighted.

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A nanocomposite with Ag nanowires embedded into poly-(vinylidene fluoride) (PVDF) has been prepared via a simple casting method. The uniform dispersion of Ag nanowires is characterized by scanning electron microscopy and the dielectric properties of composite films on volume fraction of Ag nanowires and frequency are fully investigated. The percolation threshold of the composite is relatively large, 20 vol.%. The dielectric constant of Ag nanowires/PVDF composite film is as high as 800 in the low-frequency range (100 Hz), and remains at 379 at 1000 Hz with 20 vol.% of Ag nanowires. Meanwhile, the Ag nanowires/PVDF composite film exhibits low dielectric loss of 0.15, which shows potential for applications in advanced electronics.Dependence of the effective dielectric constant of the Ag nanowires/PVDF composites on the Ag nanowires volume fraction at room temperature and 1000 Hz. And the inset is the surface of the composite film ( f Ag ¼ 20 vol.%).