Isolated Single-Atom Ni–N₅ Catalytic Site in Hollow Porous Carbon Capsules for Efficient Lithium–Sulfur Batteries

Abstract

Lithium−sulfur (Li−S) batteries suffer from multiple complex and often interwoven issues, such as the low electronic conductivity of sulfur and Li 2 S/Li 2 S 2 , shuttle effect, and sluggish electrochemical kinetics of lithium polysulfides (LiPSs). Guided by theoretical calculations, a multifunctional catalyst of isolated single-atom nickel in an optimal Ni−N 5 active moiety incorporated in hollow nitrogen-doped porous carbon (Ni−N 5 /HNPC) is constructed and acts as an ideal host for a sulfur cathode. The host improved electrical conductivity, enhanced physical-chemical dual restricting capability toward LiPSs, and, more importantly, boosted the redox reaction kinetics by the Ni−N 5 active moiety. Therefore, the Ni−N 5 /HNPC/S cathode exhibits superior rate performance, long-term cycling stability, and good areal capacity at high sulfur loading. This work highlights the important role of the coordination number of active centers in single-atom catalysts and provides a strategy to design a hollow nanoarchitecture with single-atom active sites for high-performance Li−S batteries.

Manipulating Electrocatalytic Polysulfide Redox Kinetics by 1D Core–Shell Like Composite for Lithium–Sulfur Batteries

“…[9][10][11][12][13] These critical problems are closely linked to the lithium polysulfide intermediates that are highly soluble in electrolyte and irreversibly being consumed with lithium metal, leading to the notorious shuttle effect. [14][15][16][17][18] Recently, various inorganic metal compounds have been used to regular polysulfide shuttle, including metal atoms, [19,20] metal oxides, [21][22][23][24][25][26] sulfides, [25,27,28] nitrides, [29][30][31] carbides, [32] phosphides, [33,34] and borides. [6,7,35,36] These materials possess strong chemical interactions with polysulfides, which can effectively confine polysulfides at the cathode and suppress the shuttle effect.…”

“…Recently, various inorganic metal compounds have been used to regular polysulfide shuttle, including metal atoms, [ 19,20 ] metal oxides, [ 21–26 ] sulfides, [ 25,27,28 ] nitrides, [ 29–31 ] carbides, [ 32 ] phosphides, [ 33,34 ] and borides. [ 6,7,35,36 ] These materials possess strong chemical interactions with polysulfides, which can effectively confine polysulfides at the cathode and suppress the shuttle effect.…”

Metal-organic framework nanocrystal-derived hollow porous materials: Synthetic strategies and emerging applications

“… 126 Aiming at the above problems, Li and co-workers constructed a hollow N-doped porous carbon (Ni-N 5 /HNPC) with an optimal Ni-N 5 active moiety, which acted as an ideal host for a sulfur cathode under the guidance of theoretical simulations. 127 First, the Ni-N x /C structure (x = 3–5) with the highest cathode performance was selected by first-principles calculation. The energy calculation results of the reaction step indicated that the Ni-N 5 /C structure is the best cathode candidate.…”

Ni‐CeO2 Heterostructures in Li‐S Batteries: A Balancing Act between Adsorption and Catalytic Conversion of Polysulfide

“…[ 14 , 28 , 29 , 30 , 31 ] Unfortunately, carbon materials exhibit weak catalytic activity in accelerating the redox kinetics of S 8 and Li 2 S. The strong adsorption and weak conversion of LiPSs results in insufficient utilization of S and poor cycling performance. Transition metals, such as Fe, [ 32 ] Co, [ 33 ] and Ni, [ 16 , 34 ] can provide the high electrical conductivity and good catalytic conversion in Li–S batteries, but the nonpolar metal particles cannot effectively anchor LiPSs and suppress the shuttle effect during cycling.…”