Finely‐Dispersed Ni₂Co Nanoalloys on Flower‐Like Graphene Microassembly Empowering a Bi‐Service Matrix for Superior Lithium–Sulfur Electrochemistry

Abstract

Lithium–sulfur (Li–S) batteries present a promising solution to high‐energy and low‐cost energy storage. However, the conversion‐type redox mechanism determines the poor fulfillment of battery chemistry in terms of reversibility and kinetics. Herein, a flower‐like graphene microassembly decorated with finely‐dispersed Ni2Co nanoalloy (Ni2Co@rGO) is developed as advanced host matrix for Li–S batteries. Combining computational, physicochemical, and electrochemical studies, Ni2Co nanoalloys are unveiled synergizing strong adsorbability against polysulfide shuttling and excellent catalytic activity for sulfur conversions. Meanwhile, the sophisticated architecture renders facile electron/ion transport and highly‐exposed active interfaces. These virtues collaboratively contribute to fast and durable sulfur electrochemistry with a minimum capacity degradation of 0.034% per cycle over 500 cycles and a rate capability up to 5 C. Besides, the implementation of Ni2Co@rGO as the anode matrix tames the Li redox behavior benefiting from the enhanced lithiophilicity and reduced local current density. As such, the full cell configuration pairing S‐Ni2Co@rGO cathode and Li‐Ni2Co@rGO anode realizes a favorable areal capacity of 4.53 mAh cm−2 under high sulfur loading (4.0 mg cm−2) and limited electrolyte (E/S = 6.0 mL g−1). This work offers an elaborate bi‐service matrix engineering to simultaneously improve the conversion reversibility and kinetics for superior Li–S batteries.

Recent Progress for Concurrent Realization of Shuttle‐Inhibition and Dendrite‐Free Lithium–Sulfur Batteries

“…Besides, the excellent electronic and chemical characteristics endowed the bimetallic alloy with abundant active sites and enhanced stability. To date, a certain number of alloy catalyst materials (e.g, Pd 3 Co, [134] Co x Sn y , [135] Co 3 Fe 7 , [136] FeNi, [137] and Ni 2 Co [67] ) have been utilized as Li-S sulfur cathode hosts and exhibited enhanced sulfur electrochemistry. Despite the fact that Ptbased alloy materials exhibit strong catalytic ability toward LiPS conversion, nevertheless, their high cost and scarcity restrict their practical application.…”

“…Similarly, Chen and co-workers synthesized a flower-like microsphere reduced graphene oxide assembled and loaded with a well-dispersed Ni 2 Co alloy (Ni 2 Co@rGO) as the S-host and Lihost materials for Li-S full cells. [67] Ni 2 Co@rGO microspheres were synthesized via spray-drying and subsequent calcination. When applied as the S host, the acquired materials possess welldeveloped porosity and a high specific surface with abundant active sites and interfaces to facilitate the LiPS conversion process.…”

Recent progress in zeolitic imidazolate frameworks (ZIFs)-derived nanomaterials for effective lithium polysulfide management in lithium–sulfur batteries

“…191 Subsequently, Li et al reported Ni 2 Co@rGO nanoflowers as the host of both sulfur and Li metal. 192 Even at a high sulfur loading of 4.0 mg cm −2 , the S–Ni 2 Co@rGO|Li–Ni 2 Co@rGO full cell also exhibited excellent cycle stability.…”

In Situ Reconstruction of Electrocatalysts for Lithium–Sulfur Batteries: Progress and Prospects

“…Metal has a certain potential in regulating polysulfide intermediates because of their high electrical conductivity and affinity with the sulfur atoms of polysulfides. [95,171,172] The pioneering work by Arava et al first proposed the concept of electrocatalysts using noble metal platinum (Pt) for Li-S batteries. They found that the Pt nanoparticles could accelerate the conversion of dissolved polysulfides.…”