Heterogeneous/Homogeneous Mediators for High-Energy-Density Lithium–Sulfur Batteries: Progress and Prospects

Lithium-sulfur (Li-S) batteries are considered as one of the most potential next-generation rechargeable batteries due to their high theoretical energy density. However, some critical issues, such as low capacity, poor cycling stability, and safety concerns, must be solved before Li-S batteries can be used practically. During the past decade, tremendous efforts have been devoted to the design and synthesis of electrode materials. Benefiting from their tunable structural parameters, hollow porous carbon materials (HPCM) remarkably enhance the performances of both sulfur cathodes and lithium anodes, promoting the development of high-performance Li-S batteries. Here, together with the templated synthesis of HPCM, recent progresses of Li-S batteries based on HPCM are reviewed. Several important issues in Li-S batteries, including sulfur loading, polysulfide entrapping, and Li metal protection, are discussed, followed by a summary on recent research on HPCM-based sulfur cathodes, modified separators, and lithium anodes. After the discussion on emerging technical obstacles toward high-energy Li-S batteries, prospects for the future directions of HPCM research in the field of Li-S batteries are also proposed.

Recent Advances in Hollow Porous Carbon Materials for Lithium-Sulfur Batteries.

Since the resurgence of interest in lithium–sulfur (Li–S) batteries at the end of the 2000s, research in the field has grown rapidly. Li–S batteries hold great promise as the upcoming post-lithium-ion batteries owing to their notably high theoretical specific energy density of 2600 W h kg−1, nearly five-fold larger than that of current lithium-ion batteries. However, one of their major technical problems is found in the shuttling of soluble polysulfides between the electrodes, resulting in rapid capacity fading and poor cycling stability. This review spotlights the foremost findings and the recent progress in enhancing the electrochemical performance of Li–S batteries by using nanoscaled metal compounds and metals. Based on an overview of reported functional metal-based materials and their specific employment in certain parts of Li–S batteries, the underlying mechanisms of enhanced adsorption and improved reaction kinetics are critically discussed involving both experimental and computational research findings. Thus, material design principles and possible interdisciplinary research approaches providing the chance to jointly advance with related fields such as electrocatalysis are identified. Particularly, we elucidate additives, sulfur hosts, current collectors and functional interlayers/hybrid separators containing metal oxides, hydroxides and sulfides as well as metal–organic frameworks, bare metal and further metal nitrides, metal carbides and MXenes. Throughout this review article, we emphasize the close relationship between the intrinsic properties of metal-based nanostructured materials, the (electro)chemical interaction with lithium (poly)sulfides and the subsequent effect on the battery performance. Concluding the review, prospects for the future development of practical Li–S batteries with metal-based nanomaterials are discussed.

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Metal-based nanostructured materials for advanced lithium–sulfur batteries

Due to their abundant resources and potential price advantage, potassium-ion batteries (KIBs) have recently drawn increasing attention as a promising alternative to lithium-ion batteries (LIBs) for their applications in electrochemical energy storage applications. Despite the continuous progress in identifying possible electrode materials, the development of KIBs has been challenged by different problems including low reversible capacities, unsatisfactory cycling stability, and insufficient energy density, which become serious concerns for the practical application of KIBs. In this review, we will summarize the recent advancements in both cathode and anode materials with focus on their structure–performance relationship. Meanwhile, challenges and opportunities related to the future development of KIBs are also discussed.

Recent developments in electrode materials for potassium-ion batteries

Encapsulation methods of sulfur particles for lithium-sulfur batteries: A review

Lithium–sulfur (Li–S) batteries are promising energy storage systems owing to their high theoretical energy density and low costs due to the abundant reserves of sulfur. However, the easy dissolution of intermediate polysulfides (Li2Sx, 4 < x ≤ 8) and insulating nature of sulfur have hindered their commercialization. Herein, we develop a novel confinement approach by using porous hollow carbon nanospheres (HCNs) embedded with well-dispersed cobalt monoxide (CoO) nanocrystals (CoO/HCN), which can effectively combine the advantages of physical entrapment and chemical binding interactions of sulfur species. When used as a sulfur host material, the CoO/HCN–S composite cathode with 1.4 mg cm−2 sulfur exhibits excellent electrochemical performance with high discharge capacity (996 mA h g−1 after 200 cycles at 0.2C), great rate capability (620 mA h g−1 at 5.0C) and superior cycle stability (629 mA h g−1 after 1000 cycles at 1.0C with a capacity decay of only 0.033% per cycle and 482 mA h g−1 after 1000 cycles at 2.0C with a capacity decay of only 0.043% per cycle). Furthermore, a high and stable reversible capacity of 640 mA h g−1 after cycling for 250 cycles is achieved with a higher sulfur mass loading (3.6 mg cm−2).

Porous hollow carbon nanospheres embedded with well-dispersed cobalt monoxide nanocrystals as effective polysulfide reservoirs for high-rate and long-cycle lithium–sulfur batteries

Morphological syntheses and photocatalytic properties of well-defined sub-100 nm Ag/AgCl nanocrystals by a facile solution approach

The invention relates to a method for extracting and separating mercury sulfide nanoparticles in a Mongolian medicine Menggenwusu, belonging to the field of active ingredient extraction of a traditional processed product of a Mongolian medicine. The method comprises extraction of mercury sulfide sample particles and differential separation of mercury sulfide micro-nanoparticles, wherein in the extraction, the mercury sulfide sample particles are extracted by xylene, and elemental sulfur in Menggenwusu is removed; and in the differential separation, the mercury sulfide micro-nanoparticles different in particle size can be obtained by controlling the PVP concentration, feed ratio, centrifuge speed and centrifugation time. By adopting the method provided by the invention, the extracted mercury sulfide micro-nanoparticles have high purity, stable composition and exact structure while clinical administration is more scientific; and moreover, with the separated mercury sulfide micro-nanoparticles different in particle size, the efficacy of the nanoparticles different in particle size can be compared.

Chaojun Chen

Papers

Porous hollow carbon nanospheres embedded with well-dispersed cobalt monoxide nanocrystals as effective polysulfide reservoirs for high-rate and long-cycle lithium–sulfur batteries

Morphological syntheses and photocatalytic properties of well-defined sub-100 nm Ag/AgCl nanocrystals by a facile solution approach

Method for extracting and separating mercury sulfide nanoparticles in Mongolian medicine Menggenwusu