SnS₂/TiO₂ nanohybrids chemically bonded on nitrogen-doped graphene for lithium–sulfur batteries: synergy of vacancy defects and heterostructures

Abstract

Despite their high-energy density, low cost and environmental friendliness, the commercial application of lithium-sulfur batteries (LSBs) has been plagued by their severe capacity decay during long-term cycling caused by polysulfide shuttling. Herein, we demonstrate a synergetic vacancy and heterostructure engineering strategy using a nitrogen-doped graphene/SnS2/TiO2 (denoted as NG/SnS2/TiO2) nanocomposite to enhance the electrochemical performance of LSBs. It is noted that plentiful sulfur vacancy (Vs) defects and nanosized heterojunctions are created on the NG/SnS2/TiO2 composite as proved using electron paramagnetic resonance, transmission electron microscopy and X-ray photoelectron spectroscopy, which can serve as strong adsorption and activation sites for polar polysulfide intermediates, prevent their dissolution/shuttling, and accelerate their redox reaction. The novel NG/SnS2/TiO2-S cathode delivers a high initial capacity of 1064 mA h g-1 at 0.5 C and a high capacity retention rate of 68% after 500 cycles at 0.5 C.

Lotus Root-Like Nitrogen-Doped Carbon Nanofiber Structure Assembled with VN Catalysts as a Multifunctional Host for Superior Lithium–Sulfur Batteries

“…However, commercialization of LSBs has been impeded by low S utilization, a consequence of the shuttle effect of soluble lithium polysulfides, along with fast capacity decay and low electron conductivity of S/Li 2 S 2 /Li 2 S, huge volume variation of active S upon lithiation, and corrosion of Li anodes [4][5][6][7]. In recent years, various strategies have been adopted to weaken the influence of the above issues and improve the electrochemical performance of LSBs, including modification of the separator [8][9][10][11][12][13][14], the creation of new electrolytes [15][16][17][18], the addition of protection for the Li anode [19][20][21], and improvement of the sulfur host [22][23][24][25][26][27][28]. Among these, the creation of a novel sulfur host is a promising tactic to promote sulfur utilization and buffer volume expansion in the cathode.…”

A Full Li–S Battery with Ultralow Excessive Li Enabled via Lithiophilic and Sulfilic W2C Modulation

“…[16] Moreover,B oth W 2 C@CNFs and CNFs show two typical bands about 1356 cm À1 (D band) and 1589 cm À1 (G band), which are attributed to the disordered carbon and ordered graphite, respectively.Ahigher I D /I G (1.11) of W 2 C@CNFst han CNFs (1.01) indicates the increased defect density within the W 2 Ci mpregnated in the CNFs, in which the defective disordering structure is beneficialf or LiPSs anchoring. [17] XPS analysisf urther confirms the chemical composition of W 2 C@CNFs( Figure S5). The typical IV curve is shown in sorption isothermi nF igureS6a, where the hysteresis loop suggests the mesoporous structure of W 2 C@CNFs with specific surface area of 16 m 2 g À1 based on the BET method.A ss hown in Figure S6 b, the pore size of W 2 C@CNFsi sm ainly distributed from 8 % 20 nm.…”

“…Moreover, Both W 2 C@CNFs and CNFs show two typical bands about 1356 cm −1 (D band) and 1589 cm −1 (G band), which are attributed to the disordered carbon and ordered graphite, respectively. A higher I D / I G (1.11) of W 2 C@CNFs than CNFs (1.01) indicates the increased defect density within the W 2 C impregnated in the CNFs, in which the defective disordering structure is beneficial for LiPSs anchoring [17] . XPS analysis further confirms the chemical composition of W 2 C@CNFs (Figure S5).…”

Evolution of large area TiS2-TiO2 heterostructures and S-doped TiO2 nano-sheets on titanium foils

“…The Ti 3+ states participating in these compounds can be the origin of 463 eV peak. The other peak with a binding energy of 466.4 eV can be attributed to the presence of Ti-C bonding on the sample 61 .…”