Medium‐Entropy‐Alloy FeCoNi Enables Lithium–Sulfur Batteries with Superb Low‐Temperature Performance

Abstract

Lithium‐sulfur battery suffers from sluggish kinetics at low temperatures, resulting in serious polarization and reduced capacity. Here, this work introduces medium‐entropy‐alloy FeCoNi as catalysts and carbon nanofibers (CNFs) as hosts. FeCoNi nanoparticles are in suit synthesized in cotton‐derived CNFs. FeCoNi with atomic‐level mixing of each element can effectively modulate lithium polysulfides (LiPSs), multiple components making them promising to catalyze more LiPSs species. The higher configurational entropy endows FeCoNi@CNFs with extraordinary electrochemical activity, corrosion resistance, and mechanical properties. The fractal structure of CNFs provides a large specific surface area, leaving room for volume expansion and Li2S accumulation, facilitating electrolyte wetting. The unique 3D conductive network structure can suppress the shuttle effect by physicochemical adsorption of LiPSs. This work systematically evaluates the performance of the obtained Li2S6/FeCoNi@CNFs electrode. The initial discharge capacity of Li2S6/FeCoNi@CNFs reaches 1670.8 mAh g−1 at 0.1 C under ‐20 °C. After 100 cycles at 0.2 C, the capacity decreases from 1462.3 to 1250.1 mAh g−1. Notably, even under ‐40 °C at 0.1 C, the initial discharge capacity of Li2S6/FeCoNi@CNFs still reaches 1202.8 mAh g−1. After 100 cycles at 0.2 C, the capacity retention rate is 50%. This work has important implications for the development of low‐temperature Li‐S batteries.

Rechargeable Potassium‐Ion Full Cells Operating at −40 °C

“… [9,10] This intrinsic fast kinetic can alleviate the adverse impacts of low‐temperature on battery performance. [11–16] . However, current researches on low‐temperature PIBs mainly focus on half cells with K metal as the reference electrode, while the research on cryogenic full cells is still blank [12,17] .…”

“…[5][6][7][8] In contrast, potassium (K)-ion batteries (PIBs) are promising candidates for low-temperature energy storage due to the smaller Stokes radius and weaker solventcoordination capability of K + . [9,10] This intrinsic fast kinetic can alleviate the adverse impacts of low-temperature on battery performance.. [11][12][13][14][15][16] However, current researches on low-temperature PIBs mainly focus on half cells with K metal as the reference electrode, while the research on cryogenic full cells is still blank. [12,17] Particularly, the utilization of K metal presents enormous safety hazards due to its propensity for dendrite growth and the occurrence of parasitic reactions, rendering it unsuitable for practical applications.…”

Modulating d‐Band Electronic Structures of Molybdenum Disulfide via p/n Doping to Boost Polysulfide Conversion in Lithium‐Sulfur Batteries

“…[15][16][17] Electrocatalysis has recently been mentioned as the most powerful strategy to solve the intractable issues above. [18][19][20] Many electrocatalysts have been used in Li-S batteries, including heteroatoms doped carbonaceous materials, [21][22][23] metal borides, [24,25] nitrides, [26,27] oxides, [28,29] phosphides, [30,31] sulfides, [32][33][34] selenides, [35,36] alloys, [37,38] single-atom catalysts, [39][40][41] and heterostructure. [42] These electrocatalysts effectively accelerate the electrocatalytic transformation of polysulfides and improve the electrochemical performance of Li-S batteries.…”

CoSe2anchored vertical graphene/macroporous carbon nanofibers used as multifunctional interlayers for high-performance lithium–sulfur batteries

“…Naturally, the electrical conductivity of carbon materials deteriorates owing to the introduction of pores, resulting in the degradation of battery performance. Because nonpolar carbon-based materials have a limited effect on confining the LiPS, many polar components, including metal selenides, 24 oxides, 25 sulfides, 26 nitrides, 27 phosphides, 28 carbide, 29 alloys, 30 single atoms 31 and MXenes 32 were used to interact with LiPS and catalyze the reversible reaction between S 8 and Li 2 S. Recently, cobalt selenide (CoSe x ), as the emerging catalyst, has been extensively studied owing to its excellent electrical conductivity and strong chemical bonds with LiPSs. 33–35 However, the performance of most CoSe x -based materials, particularly in the rate performance, is unsatisfactory (such as 633.1, 695.7 and 708.7 mA h g −1 at 2C in a recent study).…”