Aminomethyl‐Functionalized Carbon Nanotubes as a Host of Small Sulfur Clusters for High‐Performance Lithium–Sulfur Batteries

Abstract

Here we propose an effective strategy to stabilize small sulfur species by using aminomethyl‐functionalized carbon nanotubes (AM‐CNT) without impairing the conductive channel of the carbon nanotube (CNT) cathode. The linear Sn clusters can be anchored strongly to the AM‐CNT for the favorable size of n=5 and the maximum size of n=6 in the production of the cathode, which depresses the mass loss of active sulfur effectively and eliminates the formation of high‐order polysulfides completely during the discharge process. The most stable 3 D cross‐linked Inter‐S5‐AM‐CNT network shows a fast electron transfer redox reaction through the CNT skeleton that possesses a theoretical capacity of 1337 mA h g−1 (based on sulfur) or 592 mA h g−1 (based on the cathode). The discharge products of the linear S5 cluster tend to form a hyperbranched tight structure through N⋅⋅⋅S⋅⋅⋅Li bridges that are fully impregnated in the AM‐CNT bundles, and thus stabilize the entire system. Importantly, this study provides vital guidance into how to design cathodes based on small sulfur clusters for Li‐S batteries to depress the shuttle effect intrinsically during charge–discharge cycles, which can be extended to the other small‐sulfur‐cluster‐based batteries.

Polypyrrole/Graphene Composite Interlayer: High Redox Kinetics of Polysulfides and Electrochemical Performance of Lithium–Sulfur Batteries Enabled by Unique Pyrrolic Nitrogen Sites

“…Carbonaceous materials are the most commonly reported separator modifiers for LiÀ S batteries, [14][15][16][17][18] which could effectually alleviate the shuttle effect of PSs by physical isolation and strong chemical adsorption of PSs owing to their large surface area. However, non-polar carbon nanomaterials show weak chemical affinity to PSs and poor electrolyte wettability, and drive slow lithium-ion transfer and redox kinetics of PSs, thus the electrochemical performance, especially the rate capability and the cycling performance of the LiÀ S batteries remains unsatisfactory.…”

Recent Progress in High‐Performance Lithium Sulfur Batteries: The Emerging Strategies for Advanced Separators/Electrolytes Based on Nanomaterials and Corresponding Interfaces

“…As fundamental materials in LiÀ S cathodes, nano-carbon materials with high conductivity and porous structure (for example, graphene, carbon nanotubes(CNT S ), [57,58] porous nano carbon, carbon nanofiber, [59] carbon dots [60] etc.) have been widely used to construct carbon-sulfur composites to improve the conductivity and interfacial modifying.…”

“…[109] Nano metal oxides have been certified to interact with LiPS via strong chemical bonds, thus restricting the shuttle effect. Particularly, oxygen-rich compounds (such asV 2 O 3 , [67] TiO 2 [58,73,110] (Figure 5f), SnO 2 , [87] Co 3 O 4 , [111] MnO 2 [77,112,113] ) have been successfully developed as LiPS traps to enhance the electrochemical stability. Ma et al proposed a new strategy involving the incorporation of a 3D functional spongy framework as LiPS reservoir layer, which had a hierarchical architecture composed of highly conductive Ni foam/graphene/carbon nanotubes/ MnO 2 nanoflakes (NGCM).…”

“…Nano metal oxides have been certified to interact with LiPS via strong chemical bonds, thus restricting the shuttle effect. Particularly, oxygen‐rich compounds (such asV 2 O 3 , [67] TiO 2 [58,73,110] (Figure 5f), SnO 2 , [87] Co 3 O 4 , [111] MnO 2 [77,112,113] ) have been successfully developed as LiPS traps to enhance the electrochemical stability. Ma et al.…”

The Potential of Phosphorus Nitride Monolayer for Li–S Battery from the Anchoring and Diffusing Perspective: A First‐Principles Study

“…[4,5] At present, an accepted fact is that during the battery discharging, the sulfur (S 8 ) and its intermediate products lithium polysulfides (Li 2 S n n = 1, 2, 4, 6, 8) have low electrical conductivity [6,7] and the long-chain Li 2 S n (n = 4, 6, 8) cluster will dissolute in the electrolyte which is called "shuttle effect," causing a loss of battery capacity. [8,9] Previous studies have shown that the most important solution to suppress the shuttle effect of Li-S batteries is to design excellent sulfur-electrode nanomaterials to enhance the adsorption of soluble the long-chain lithium polysulfides and prevent its dissolution. [10,11,12] Carbon-based cathodes such as carbon hollow porous materials [13,14] and graphene nanosheets [15] have been investigated widely in sulfur-electrode nanomaterials so far because they have relatively high electrical conductivity, lightweight, and high stability.…”