Improved Electrochemical Performance of Lithium-Sulfur Batteries with Boron-Doped Zinc Cobalt Sulfide Catalyst-Modified Separators

Lithium-sulfur (Li-S) batteries possess considerable potential for high theoretical energy density; however, their practical implementation has been impeded by the polysulfide shuttle effect, resulting in inadequate cycling stability. This study addresses this challenge by synthesizing and applying a boron-doped zinc cobalt sulfide catalyst (B-ZnCo۲S۴) as a separator coating. The investigation demonstrates that B-ZnCo۲S۴-modified separators significantly enhance the electrochemical characteristics of Li-S batteries. The B-ZnCo۲S۴ and pristine ZnCo۲S۴ catalysts were synthesized using a solvothermal method, and their morphological disparities were analyzed via scanning electron microscopy (SEM). Characterization techniques affirm successful boron doping without altering the crystal structure. Batteries assembled with B-ZnCo۲S۴-modified separators exhibit superior electrochemical performance compared to those with ZnCo۲S۴-modified separators, as evidenced by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and Linear Sweep Voltammetry (LSV). The B-ZnCo۲S۴ battery demonstrates higher catalytic activity, resulting in lower polarization voltage and charge transfer impedance. Furthermore, UV-Vis analysis reveals enhanced adsorption capabilities of lithium polysulfides by B-ZnCo۲S۴. During rate testing, the B-ZnCo۲S۴ battery exhibits an impressive specific capacity exceeding ۵۰۰ mAh/g at ۴C, while sustaining capacities above ۸۰۰ and ۹۰۰ mAh/g at reduced rates of ۰.۵C and ۰.۲C, respectively, indicating excellent reversibility. In extended cycling tests of ۲۰۰ and ۵۰۰ cycles, the battery demonstrates exceptional cycling stability, with decay rates of only ۰.۱۶% and ۰.۰۷% at ۰.۵C and ۱C, respectively. SEM analysis further confirms the effective inhibition of lithium dendrite formation by B-ZnCo۲S۴. Therefore, the utilization of B-ZnCo۲S۴ as a catalyst holds great promise in augmenting the operational efficiency and longevity of Li-S batteries. These discoveries present encouraging prospects for the advancement of Li-S batteries, enabling enhanced performance and improved practical feasibility.

کلیدواژه ها:

Lithium-sulfur battery ، Boron-doped zinc cobalt sulfide ، Electrochemical characterization ، Cycling performance ، Rate capability