Synergistic Effects of Co₃Se₄ and Ti₂C₃T_x for Performance Enhancement on Lithium–Sulfur Batteries

Abstract

As electronic equipment develops rapidly, higher requirements are placed on electrochemical energy-storage devices. These requirements can be met by a lithium− sulfur (Li−S) battery since it has an impressive energy density of 2600 Wh kg −1 and a high theoretical specific capacity of 1675 mAh g −1 . Pitifully, the sluggish redox reaction kinetics and the shuttle effect of polysulfide seriously limit its applications. Separator modification has been proven to be an effective strategy for improving the performance of Li−S batteries. Herein, we have designed a competent three-dimensional separator. It is obtained by embedding Co 3 Se 4 nanoparticles on nitrogen-doped porous carbon (Co 3 Se 4 @N−C) by high-temperature selenization of ZIF-67, which are compounded with Ti 3 C 2 T x by electrostatic dispersion self-assembly, and the compound is used to adjust the surface properties of a polypropylene (PP) separator. Due to the synergistic effect of the superior catalytic performance of Co 3 Se 4 @N−C and the enhancement of adsorption and conductivity bestowed by Ti 3 C 2 T x , lithium−sulfur batteries perform excellently with the modified PP separator. Specifically, the battery with a Co 3 Se 4 @N−C/Ti 3 C 2 T x -modified PP separator exhibits an outstanding rate performance of 787 mAh g −1 at 4C, and stable performance is maintained after 300 cycles at 2C. The density functional theory (DFT) calculations are also performed to confirm the synergistic effect of Co 3 Se 4 @N−C and Ti 3 C 2 T x . This design integrates the merits of catalysis and adsorption and provides a new method for constructing high-performance lithium−sulfur batteries. KEYWORDS: lithium−sulfur battery, Co 3 Se 4 , Ti 3 C 2 T x , separators, adsorption, catalysts

Green Large-Scale Preparation of Na3V2(PO4)3 with Good Rate Capability and Long Cycling Lifespan for Sodium-Ion Batteries

“…Electrochemical impedance spectroscopy (EIS) was employed to further explore the dynamics exhibited by the Na 3 V 2 (PO 4 ) 3 materials. The resulting Nyquist plots in Figure h display a semicircular pattern at high frequencies indicating charge transfer resistance ( R ct ), and a linear trend at low frequencies representing Warburg impedance ( Z ω). , The semicircular radius of NVP/C–Na is significantly smaller compared to the others, indicating that the carbon coating and porous structure can effectively enhance the charge transfer. In addition, a steeper slope was observed for NVP/C–Na in comparison to other Na 3 V 2 (PO 4 ) 3 samples, which suggests that incorporating a sodium source into the cathode electrode material facilitates a greater diffusion of Na + within the NVP particles.…”

Solid-State Synthesis of Na4Fe3(PO4)2P2O7/C by Ti-Doping with Promoted Structural Reversibility for Long-Cycling Sodium-Ion Batteries

“…The decrease in iron content is most likely due to the fact that the ratio of Fe to P elements in raw FePO 4 was only approximately 0.74. The N 2 adsorption–desorption isotherm curves and Barrett–Joyner–Halenda (BJH) pore-size distribution plots are shown in Figure S7 . Both samples are characterized by typical type IV isotherms with narrow hysteresis loops, indicating a porous structure.…”

“…The N 2 adsorption−desorption isotherm curves and Barrett−Joyner− Halenda (BJH) pore-size distribution plots are shown in Figure S7. 46 Both samples are characterized by typical type IV isotherms with narrow hysteresis loops, indicating a porous structure. The surface area of Ti-NFPP equals to 8.0 m 2 g −1 , which is significantly higher than that for NFPP (4.0 m 2 g −1 ).…”

Recent progress in MXenes-based lithium-sulfur batteries

“…Finally, LSBs based on MCCoS/PP separators showed a satisfactory cycling performance at 7 C, including a high first discharge capacity of 698.1 mAh g -1 , low decay rate per cycle of 0.033%, and high Coulombic efficiency of 99%-100% after 1,000 cycles [Figure 10G]. The composites of other metal compounds with MXenes as modification layers of separators for LSBs have also been discussed, such as hierarchical porous carbon aerogels embedded with small-sized TiO 2 nanoparticles (HPCA-TO) [115] , MXene@WS 2 [116] , HE-MXene doped graphene composite (HE-MXene/G) [117] , and Co 3 Se 4 nanoparticles embedded in nitrogen-doped porous carbon/Ti 3 C 2 T x (Co 3 Se 4 @N-C/Ti 3 C 2 T x ) [118] .…”