For lithium-sulfur batteries, commercial application is hindered by the insulating nature of sulfur and the dissolution of the reaction intermediates of polysulfides. Here, we present an ordered meso-microporous core-shell carbon (MMCS) as a sulfur container, which combines the advantages of both mesoporous and microporous carbon. With large pore volume and highly ordered porous structure, the "core" promises a sufficient sulfur loading and a high utilization of the active material, while the "shell" containing microporous carbon and smaller sulfur acts as a physical barrier and stabilizes the cycle capability of the entire S/C composite. Such a S/MMCS composite exhibits a capacity as high as 837 mAh g(-1) at 0.5 C after 200 cycles with a capacity retention of 80% vs the second cycle (a decay of only 0.1% per cycle), demonstrating that the diffusion of the polysulfides into the bulk electrolyte can be greatly reduced. We believe that the tailored highly ordered meso-microporous core-shell structured carbon can also be applicable for designing some other electrode materials for energy storage.

be more suitable for Na + insertion. As proposed by Stevens and Dahn, the sodium storage behaviors occurring in hard carbons obey a "house of cards" model, [ 12 ] and Cao et al. have provided theoretical supports, demonstrating that carbon materials with an interlayer distance of >3.7 nm is electrochemically active for Na + insertion. [ 11b ] Moreover, Wang's team has confi rmed that an expanded graphite anode with an enlarged interlayer distance of 4.3 nm has a high sodium storage performance. [ 11c ] The expanding of the interlayer distances can result similar effects in facilitating the Na + insertion in hard carbon. [ 11d ] It is worth noting that the doping covalent heteroatom is capable of turning the physicochemical properties of carbonaceous materials [ 13 ] and N-doped carbon materials have exhibited the enhanced sodium storage performance by enhancing the Na adsorption capability and electronic conductivity. [ 14 ] Furthermore, another heteroatom of sulfur is also proposed to enhance the sodium storage capacity by affecting the interlayer of carbon. [ 5b ] On the basis of the mentioned above, the codoping of nitrogen and sulfur would synergically facilitate the Na + ion insertion and the electron transport.From the perspective of sustainability, cellulose as the most abundant renewable resource on earth has attracted much attentions in many fi elds including energy sources. [ 15 ] In our laboratory, the dissolution of cellulose and polyaniline (PANI) has been realized in a NaOH/urea aqueous solution with cooling via a physical process, and regenerated cellulose/PANI fi lms, fi bers and hydrogels have been successfully fabricated. [ 16 ] It has given us the motivation to develop cellulose/PANI microspheres, which not only can donate nitrogen, but also can prepare the hard carbon with a low-cost and large-scale strategy. Thus, a worthwhile endeavor would be to design and fabricate the carbon microspheres with nitrogen and sulfur dual-doping by pyrolyzing the cellulose/PANI microspheres containing dodecyl benzene sulfonic acid (DBSA) via a simply, "green" and low cost route to construct anode materials for SIBs. It is not hard to imagine that after carbonization, the doped nitrogen and sulfur heteroatoms donated by PANI and DBSA can induce the defects and the expanded interlayer distance of the carbon microspheres, leading to the enhancement of the Na adsorption capability, mobility and electronic conductivity, resulting in a high-performance anode for SIBs.Here, for the fi rst time, N/S codoped carbon microspheres (NSC-SP) with expanded interlayer as a high-rate and longlife SIBs anode were facilely constructed by pyrolyzing the cellulose/PANI (9:1 by weight) microspheres containing DBSA dopant. First, the regenerated cellulose/PANI composite microspheres containing DBSA were prepared from the Rechargeable batteries are emerging energy storage techniques for the integration of renewable energy sources like solar energy and wind power. [ 1 ] Lithium ion batteries (LIBs) represent one of the most matu...

A flexible asymmetric supercapacitor (ASC) with high energy density is designed and fabricated using flower‐like Bi2O3 and MnO2 grown on carbon nanofiber (CNF) paper as the negative and positive electrodes, respectively. The lightweight (1.6 mg cm−2), porous, conductive, and flexible features make the CNF paper an ideal support for guest active materials, which permit a large areal mass of 9 mg cm−2 for Bi2O3 (≈85 wt% of the entire electrode). Thus, the optimal device with an operation voltage of 1.8 V can deliver a high energy density of 43.4 μWh cm−2 (11.3 W h kg−1, based on the total electrodes) and a maximum power density of 12.9 mW cm−2 (3370 W kg−1). This work provides an example of large areal mass and flexible electrode for ASCs with high areal capacitance and high energy density, holding great promise for future flexible electronic devices.

Lithium-ion batteries (LIBs), with relatively high energy density and power density, have been considered as a vital energy source in our daily life, especially in electric vehicles. However, energy density and safety related to thermal runaways are the main concerns for their further applications. In order to deeply understand the development of high energy density and safe LIBs, we comprehensively review the safety features of LIBs and the failure mechanisms of cathodes, anodes, separators and electrolyte. The corresponding solutions for designing safer components are systematically proposed. Additionally, the in situ or operando techniques, such as microscopy and spectrum analysis, the fiber Bragg grating sensor and the gas sensor, are summarized to monitor the internal conditions of LIBs in real time. The main purpose of this review is to provide some general guidelines for the design of safe and high energy density batteries from the views of both material and cell levels.

Rechargeable batteries with lithium metal anodes exhibit higher energy densities than conventional lithium-ion batteries. Solid-state electrolytes (SSEs) provide the opportunity to unlock the full potential of lithium metal anodes and...