Defect‐engineered Sulfur Vacancy Modified NiCo₂S_4‐x Nanosheet Anchoring Polysulfide for Improved Lithium Sulfur Batteries

Abstract

The low conductivity of sulfur and the shuttle effect of lithium polysulfides (LiPSs) are the two intrinsic obstacles that limit the application of lithium–sulfur batteries (LSBs). Herein, a sulfur vacancy introduced NiCo2S4 nanosheet array grown on carbon nanofiber (CNF) membrane (NiCo2S4‐x/CNF) is proposed to serve as a self‐supporting and binder‐free interlayer in LSBs. The conductive CNF skeleton with a non‐woven structure can effectively reduce the resistance of the cathode and accommodate volume expansion during charge–discharge process. The bonding between CNF matrix and NiCo2S4 nanosheet is enhanced by in situ growth, ensuring fast electron transfer. Besides, the sulfur vacancies in NiCo2S4 enhance the chemisorption of LiPSs, and the highly active sites at vacancies can accelerate the LiPSs conversion kinetics. LSB paired with NiCo2S4‐x/CNF interlayer achieved improved stability in 500 cycles at 0.2 C and long life of 3000 cycles at 3 C. More importantly, a high areal capacity of 9.69 mAh cm−2 is achieved with a sulfur loading of 10.8 mg cm−2 and a low electrolyte to sulfur (E/S) ratio of 4.8. This work provides insight into the sulfur vacancy in catalysis design for LiPSs conversion and demonstrates a promising direction for electronic defect engineering in material design for LSBs.

Co9S8 core–shell hollow spheres for enhanced oxygen evolution and methanol oxidation reactions by sulfur vacancy engineering

“…Furthermore, a new peak at a higher value of 162.7 eV in Co 9 S 8− x -M spheres appears, assigned to sulfur with low coordination, that confirms the existence of sulfur vacancies in Co 9 S 8− x -M spheres. 48–50 Furthermore, Co 9 S 8 and Co 9 S 8− x -M spheres exhibited an electron paramagnetic resonance (EPR) signal at g = 2.004 (Fig. 3c), which could be identified for the electrons trapped on sulfur vacancies.…”

Yttrium-Containing Solid Electrolyte Interphase Safeguards Lithium Anodes in Lithium–Sulfur Batteries

“…2 The pursuit of green development in both the economy and society has resulted in a significant request for energy storage systems with high energy density. 3 In this regard, lithium−sulfur batteries (LSBs) have emerged as a promising solution, boasting an impressive high discharge capacity of 1675 mA h g −1 . Notably, the energy density of LSBs is markedly superior to that of conventional lithium-ion batteries.…”

Ultrafine Ni12P5 nanoparticle-embedded carbon with abundant catalytic activity sites as separator modifiers in high-performance lithium–sulfur batteries

“…Lithium–sulfur (Li–S) batteries have an ultra-high theoretical capacity (1675 mA h g −1 ) and are regarded as one of the promising candidates for next-generation energy storage systems. 1–7 Nevertheless, the large-scale commercialization of Li–S batteries is still subject to various obstacles, including the low conductivity of sulfur and discharge products (Li 2 S and Li 2 S 2 ), large volume expansion, and the shuttle effect of polysulfides, which cause a rapid capacity decay and low coulombic efficiency. 8–11 To solve such issues, the strategies mainly concentrate on the fortification of the sulfur cathode and lithium anode, electrolyte improvement, and the modification of separators.…”