Manipulating Redox Kinetics using p-n Heterojunction Biservice Matrix as both Cathode Sulfur Immobilizer and Anode Lithium Stabilizer for Practical Lithium-Sulfur Batteries.

As an attractive high-energy-density technology, the practical application of lithium-sulfur (Li-S) batteries is severely limited by the notorious dissolution and shuttle effect of lithium polysulfides (LiPS), resulting in sluggish reaction kinetics and uncontrollable dendritic Li growth. Herein, a p-n typed heterostructure consisting of n-type MoS2 nanoflowers embedded with p-type NiO nanoparticles is designed on carbon nanofibers (denoted as NiO-MoS2 @CNFs) as both cathode sulfur immobilizer and anode Li stabilizer for practical Li-S batteries. Such p-n typed heterostructure is proposed to establish the built-in electric field across the heterointerface for facilitated the positive charge to reach the surface of NiO-MoS2 , meanwhile inherits the excellent LiPS adsorption ability of p-type NiO nanoparticles and catalytic ability of n-type MoS2 . As the anode matrix, the implementation of NiO-MoS2 heterostructure can prevent the growth of Li dendrites by enhancing the lithiophilicity and reducing local current density. The obtained Li-S full battery exhibits an ultra-high areal capacity over 7.3 mAh cm-2 , far exceeding that of current commercial Li-ion batteries. Meanwhile, a stable cycling performance can be achieved under low electrolyte/sulfur ratio of 5.8 µL mg-1 and negative/positive capacity ratio of 1. The corresponding pouch cell maintains high energy density of 305 Wh kg-1 and stable cycling performance under various bending angles.

Conductive Al-Doped ZnO Framework Embedded with Catalytic Nanocages as a Multistage-Porous Sulfur Host in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries possess many practical challenges including the lithium polysulfide (LiPS) "shuttle effect" and their sluggish conversion kinetics. To address these issues, a unique hierarchical porous architecture, combining highly conductive ordered macroporous skeleton and embedded microporous particles is rationally designed as a dual-effective polysulfide immobilizer and conversion promoter. In this nanoporous architecture, Al-doped ZnO (AZO) acts as a conductive macroporous framework, profiting chemical anchoring of LiPS as well as facilitating electrolyte infiltration and ion diffusion; Co nanoparticle-anchored N-doped carbon (Co-NC) derived from CoZn-metal-organic framework is embedded in the macropores to further strengthen the LiPS adsorption, catalytically accelerating conversion kinetics of LiPS simultaneously. Consequently, the Co-NC@AZO/S cathode delivers a notable rate capability of 635.5 mA h g-1 at 5 C. A high area capacity of about 5.8 mA h cm-2 with a mass loading of 6.8 mg cm-2 is also achieved under a lean electrolyte (E/S = 5.7). Additionally, the Li-S pouch cells equipped with Co-NC@AZO can be extended to sulfur loading as high as 4.0 mg cm-2, delivering a superb capability of 897.5 mA h g-1 after 100 cycles. This work puts forward a design for stably cycled and practically viable Li-S batteries.