Lithium sulfur (Li–S) batteries can offer great opportunities for the next-generation energy storage systems with tremendous energy density. However, challenges still exist in practical Li–S batteries including low sulfur utilization, and poor cycling stability and rate capability. Herein, we propose a novel hybrid catalyst structure by in situ implanting nanocrystal CoS2 in three-dimensional honeycomb-like hierarchical porous graphitic carbon (HPGC) for high-performance Li–S batteries. A unique synergistic absorption-catalysis-functional effect is demonstrated by comprehensive experimental and theoretical analysis: strong physical and chemical co-absorption effects are originated from the large quantity of microporous HPGC and the polar surface of metallic CoS2; the introduced nanocrystal CoS2 with a large specific area can impose an exceptional catalytic effect on the liquid–liquid, solid–liquid, and solid–solid phase redox reactions in Li–S batteries; the reaction dynamics are further guaranteed by the multifunctional properties of the HPGC backbone, including the capabilities in polysulfide sustention, reaction product transportation, electrolyte compensation, and efficiency in assisting diverse electrochemical reaction dynamics. In this way, our results not only develop a novel CoS2@HPGC structure, but also provide fundamental understanding on the catalytic dynamics during each reaction process. Moreover, we further propose the necessity and philosophy of the rational design of catalysts’ special structure, which can fulfill the functional dynamics requirements of Li–S batteries, and can be promoted to other Li–S-related cathode design and composite catalytic structure design.

Pursuing scalable production of porous carbon with facile and environmentally friendly synthesis methodology is a global goal. Herein, a unique hierarchical porous graphitic carbon (HPGC) with outstanding textural characteristics is achieved by a special synergistic activation mechanism, in which the low-temperature molten state of polymorphisms can induce a high-rate liquid phase porous activation. HPGC with high specific surface area (SSA, ∼2571 m2 g–1) and large pore volume (PV, ∼2.21 cm3 g–1) can be achieved, which also possesses the capability to tune textural characteristics (i.e., SSA, PV, pore size distribution, etc.) within a wide range. Furthermore, the pilot-scale production of HPGC is accomplished, which shows similar textural characteristics to the lab-scale HPGC. Due to the unique structure of HPGC and the capability of the textural control, it can be applicable in a variety of energy storage, energy conversion, and catalysis applications. The applications of pilot-scale HPGC products in supercapacitors and lithium sulfur batteries are highlighted in this work. Furthermore, the synergistic activation strategy can be promoted to other alkali-based carbon activation routes, which can open up new possibilities for the activated carbon production and lead to more widespread industrialized applications of HPGC.

and its discharge products (Li 2 S 2 /Li 2 S) are poor and will largely hinder the reaction kinetics of Li-S system; while the dissolution and migration of lithium polysulfides (LiPS) will lead to undesired shuttle effects and poor cycle life, all of which will hamper the large scale application of Li-S batteries. [7][8][9] In the view of the above problems, scientists have done a lot of exploration on improving the reaction dynamics. A series of carbon materials, such as meso/ microporous carbon, carbon nanotubes and graphene, are widely used to remission the shuttle effect of Li-S batteries, which can provide conductive framework, alleviate the volume change of electrodes, and physically constrain LiPS. [10] However, the physical encapsulation of the nonpolar carbon-based sulfur host is not effective enough to restrain the shuttle effect. A common practice in the research of Li-S batteries is the adoption of different catalysts to boost its conversion chemistry. An effective way to solve this problem is to use polar metal compounds, such as transition metal oxides, [11][12][13] nitride [14] and sulfides, [15][16][17] to improve the hydrophobic interface of carbon materials and provide extra chemical adsorption effect. Transition metal sulfides, such as CoS 2 , MoS 2 and VS 4 , are most welcomed catalysts, which not only possess good conductivity and intensive affinity for LiPS, but also show great potential in LiPS adsorption and catalysis effect for the key reactions of Li-S battery. [18] Various catalysts are adopted to boost the conversion chemistry of Lithium sulfur (Li-S) batteries, but most of them are electrochemical-active in a working Li-S cell, and the changes of their chemical state and the induced influence toward the Li-S catalytic mechanism are unclear. Herein, a dynamic catalytic mechanism is proposed by the selection of Li + -interaction-reversible VS 2 catalyst as a representative species to address this issue. The VS 2 catalyst with ultrastable Li + intercalation/deintercalation characteristics, fast charge transport capability, and active capacity contribution can provide a strong and dynamic chemisorption toward polysulfide (LiPS). The resulting Li-S batteries exhibit excellent cyclability at 3 C with capacity attenuation of 81.23% over 250 cycles and good rate capability up to 8 C. Moreover, a new insight toward the dynamic catalytic changes induced by the prominent Li + intercalation process of metal sulfide is proposed, which can provide more opportunities for the evolutional design for Li-S catalysts.

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