(25c) Invited: Novel Materials and Modification of Lithium Sulfur Batteries of Enhanced Performance

The emerging needs of EV/HEV with longer driving range and more stable performance have significantly aroused the interest in novel battery chemistry with higher energy density and specific capacity other than conventional Li-ion batteries. The Li-S battery with a high theoretical energy density of around 2500 Wh kg^-1 is considered as a promising alternative as novel secondary batteries. However, several inevitable drawbacks are greatly hindering its practical application, which could be attributed to insulating nature of sulfur and its reduction products (Li₂S₂ and Li₂S), shuttling mechanism of dissolved polysulfides and degradation of lithium metal anode.

As for the improvement of battery performance, we designed 3 different of matrix of cathode materials in diverse nanostructure including titanium nitride nanoparticles, titanium nitride nanotubes and nickel nanoparticles dispersed on graphene. The electrochemical tests of long cycles of charging/discharging and rate performance would be conducted to show their effect on the enhancement of Li-S battery performance and stability over long cycles. In addition, physical characterization, including SEM, XRD, EDS and TEM etc., would be utilized to characterize the surface morphology, crystal structure and chemical element distribution.

Furthermore, our efforts come to the protection of lithium metal anode. Transition metal acetates would be used as the electrolyte additives to prevent the gradual degradation of lithium anode. It is found out that the stability of battery performance could be greatly improved after appropriate selection of additive. Also, the materials characterization results indicate that the passivation film on lithium metal surface become smoother to decrease lithium plating sites, and stronger to suppress the growth of lithium dendrites.