ABSTRACT
Lithium-sulfur batteries (LSBs) are widely regarded as reliable novel secondary batteries due to their low price and high capacity. Nevertheless, the notorious "shuttle effect" limits the commercialization of LSBs. In order to solve this problem, we fabricated a Ni3S2-Ni/C composite through carbonization, vulcanization and hydrothermal reactions by using a Ni-MOF precursor and applied it as a separator modification layer to enhance the electrochemical properties of LSBs. To further increase the conductivity of the material, a small amount of GO was added during the experiment. The prepared material was also used as separator modified coating material to optimize the electrochemical performance of LSBs. The as prepared Ni3S2-Ni/C(GO) composite shows good conductivity and has a superior porous structure and abundant active sites. Lithium polysulfides (LPs) can be physically confined and chemically adsorbed, what is more, the Ni and Ni3S2 active sites enable fast conversion of LPs which further optimizes the rate performance. From the cycle performance measurement, the initial discharge specific capacity of the Ni3S2-Ni/C(GO) modified separator battery is found to be 1263.4, 1181.5, 1090.6, and 840.3 mA h g-1 at 0.05, 0.1, 0.3 and 0.5C, respectively. After 400 charge/discharge cycles at 0.5C, the capacity remains at 483.6mA h g-1 with a capacity retention ratio of 57.56%.
ABSTRACT
The shuttle effect of soluble lithium polysulfide (LiPS) is a major obstacle to the practical application of lithium-sulfur (Li-S) batteries. In order to reduce the negative impact of the shuttle effect, Nd-MOF was combined with carbon nanofibers (CNFs) so that Nd-MOF was embedded in the CNFs and the Nd2O3-C/CNF composite was realized as a separation modification material. This embedded structure made the combination between Nd2O3-C and CNFs tighter, and it exhibited better synergistic effects to inhibit the shuttle effect of polysulfides while also enhancing the tensile strength of the separator and improving the safety performance of the battery. Based on these advantages, a lithium-sulfur coin cell with the Nd2O3-C/CNF-modified separator exhibited excellent electrochemical performance.