Reconstructable Carbon Monolayer-MoS2 Intercalated Heterostructure Enabled by Atomic Layers-Confined Topotactic Transformation for Ultrafast Lithium Storage.

The intercalation structure of two-dimensional materials with expanded interlayer distance can facilitate mass transport, which is promising in fast-charging lithium-ion batteries (LIBs). However, the designed intercalation structures will be pulverized and destroyed under tough working conditions, causing overall performance deterioration of the batteries. Here, we present that an intercalated heterostructure made of the typical layered material of MoS2 intercalated by N-doped graphene-like carbon monolayer (MoS2/g-CM) through a polymer intercalation strategy exhibits a unique behavior of reversible reconstructability as an LIB anode during cycling. A mechanism of "carbon monolayers-confined topotactic transformation" is proposed, which is evidenced by substantial in/ex situ characterizations. The intercalated heterostructure of MoS2/g-CM featuring a reconstructable property and efficient interlayer electron/ion transport exhibits an unprecedented rate capability up to 50 A g-1 and outstanding long cyclability. Moreover, the proposed strategy based on g-CM intercalation has been extended to the MoSe2 system, also realizing reconstructability of the intercalated heterostructure and improved LIB performance, demonstrating its versatility and great potential in applications.

A Ternary (P, Se, S) Covalent Inorganic Framework as a Shuttle Effect-Free Cathode for Li-S Batteries.

Developing new cathode materials to avoid shuttle effect of Li-S batteries at source is crucial for practical high-energy applications, which, however, remains a great challenge. Herein, a new class of sulfur-containing ternary covalent inorganic framework (CIF), P4 Se6 S40 , is explored, by simply comelting powders of P, S, and Se. The P4 Se6 S40 CIF with open framework enables all active sites available during electrochemical reactions, giving a high capacity delivery. Moreover, introducing Se atoms can improve intrinsic electronic conductivity of S chains yet without remarkably compromising the capacity because Se is also electrochemical active to lithium storage. More importantly, Se atoms in S-Se chains can serve as a heteroatom barrier to block the bonding of S atoms around, effectively avoiding the formation of long-chain polysulfides during cycling. Besides, stable Li3 PS4 with a tetrahedral configuration formed after lithiation works as not only a good ionic conductor to promote Li ion diffusion, but a three-dimensional spatial barrier and chemical anchor to suppress the dissolution and diffusion of lithium polysulfides (LiPS), further inhibiting the shuttle effect. Consequently, the P4 Se6 S40 cathode delivers high capacity and excellent capacity retention with even a high loading of 10.5 mg cm-2 which far surpasses the requirement for commercial applications.

Tailoring Hollow Nanostructures by Catalytic Strategy for Superior Lithium and Sodium Storage.

Nowadays, a novel catalyzed strategy for designing 3D carbon nanosheet frameworks is a wide concern in the field of energy storage. Herein, a 3D hollow structure with nickel and nanographitic domains is presented for fabrication of functionalized hollow microporous carbon embedded with expanded defective nanographitic domains or hollow nickel oxide composites. The hollow microporous carbon coupling nanographitic domains exhibits excellent long-term cycling (4000 cycles for lithium storage, 2000 cycles for sodium storage), which is mainly due to the formation of defects in the nanographite for catalytic strategy. The hollow nickel oxide composites show the capacities of 1093 mA h g-1 after 400 cycles with the high Coulombic efficiency at a current density of 200 mA g-1 for lithium storage and superior rate performance at different current densities for sodium storage. Stable and great energy storage features stem from the fact that the hollow structure can provide more active sites for ionic diffusion/storage and a free shuttle space for electrons.

Simple method to construct three-dimensional porous carbon for electrochemical energy storage.

A 3D porous carbon matrix with a high nitrogen content has been synthesized by employing particles of a nitrogen-enriched superabsorbent polymer (SAP) from the waste diapers of newborn babies. The derived material exhibits an ultrathin layered structure with interconnected pores and a large specific surface area. As it inherits the unique skeleton of the functional polymer from waste diapers, the resulting material (NSAPC-W) has been assessed as an inserting host anode with excellent ultralong cycling performance, as well as steady rate capability for both Li+ and Na+ ions in half cells. Furthermore, the unique structure imparts intimate structural interconnectivity, wide open channels for ion diffusion, and a large accessible surface area, as well as high structural stability, and opens up a wide horizon for electrochemical applications.