Selective Adsorption and Electrocatalysis of Polysulfides through Hexatomic Nickel Clusters Embedded in N-Doped Graphene toward High-Performance Li-S Batteries

Abstract

<jats:p>The shuttle effect hinders the practical application of lithium-sulfur (Li-S) batteries due to the poor affinity between a substrate and Li polysulfides (LiPSs) and the sluggish transition of soluble LiPSs to insoluble Li<jats:sub>2</jats:sub>S or elemental S. Here, we report that Ni hexatomic clusters embedded in a nitrogen-doped three-dimensional (3D) graphene framework (Ni-N/G) possess stronger interaction with soluble polysulfides than that with insoluble polysulfides. The synthetic electrocatalyst deployed in the sulfur cathode plays a multifunctional role: (i) selectively adsorbing the polysulfides dissolved in the electrolyte, (ii) expediting the sluggish liquid-solid phase transformations at the active sites as electrocatalysts, and (iii) accelerating the kinetics of the electrochemical reaction of multielectron sulfur, thereby inhibiting the dissolution of LiPSs. The constructed S@Ni-N/G cathode delivers an areal capacity of 9.43 mAh cm<jats:sup>-2</jats:sup> at 0.1 C at S loading of 6.8 mg cm<jats:sup>-2</jats:sup>, and it exhibits a gravimetric capacity of 1104 mAh g<jats:sup>-1</jats:sup> with a capacity fading rate of 0.045% per cycle over 50 cycles at 0.2 C at S loading of 2.0 mg cm<jats:sup>-2</jats:sup>. This work opens a rational approach to achieve the selective adsorption and expediting of polysulfide transition for the performance enhancement of Li-S batteries.</jats:p>

Constructing high gravimetric and volumetric capacity sulfur cathode with LiCoO2 nanofibers as carbon-free sulfur host for lithium-sulfur battery

“…With the overall reaction of 2Li + S = Li 2 S, some fundamental issues exist in Li-S chemistry, including the insulation of sulfur/Li 2 S, the volume variation of the cathode during cycling, the shuttle of soluble intermediate lithium polysulfides (LiPS) in ether-based electrolyte, and dendrites/cracks on lithium anode [4][5]. In the past decade, great efforts have been made to tackle these issues, such as employing sophisticated cathode structure [6][7][8], heteratom-doped carbon [9][10][11], polar compounds [12][13][14][15][16], interlayers [17][18], functional separators [19][20], novel binders [21][22], and stabilized anode [23][24][25][26]. As a result, the battery performance has improved to a large extent.…”

Emerging Catalysts to Promote Kinetics of Lithium–Sulfur Batteries

“…In order to achieve selective adsorption toward specific LiPSs, Ling and co‐workers successfully embedded nickel atomic clusters in a N‐doped 3D graphene framework (Ni–N/G) through a molten‐salt method. [ 136 ] DFT results combined with adsorption experiments proved that the Ni–N/G can not only selectively collect LiPSs dissolved in electrolyte, but also continuously bind with insoluble Li 2 S 2 /Li 2 S to “seize” the catalytic sites, which accelerated the multi‐electron reaction kinetics to reduce the dissolution of LiPSs in electrolyte.…”

Graphene-Based Nanomaterials as the Cathode for Lithium-Sulfur Batteries

“…The above studies provide important theoretical support for Fe/N co-doped graphene. Based on the above theoretical research, Ji et al prepared a Ni–N co-doped 3D graphene framework as cathode material for LSBs (S@Ni-N/G) [ 66 ], and its discharge capacity at 0.2 C was 1103.6 mAh·g −1 , the capacity was stable at 953.5 mAh·g −1 , and the coulombic efficiency was as high as 97% after 100 cycles.…”