Improved capacity retention of low cost sulfur cathodes enabled by a novel starch binder derived from food

Abstract

Rechargeable lithium sulfur batteries are attracting great attention in recent years due to their high theoretical energy density, but they still suffer from poor cycle performance and other drawbacks. Up to now, most researchers have focused on the design of the state of the art S-containing composites or new and complex electrode architectures to improve their electrochemical performances. However, simple and low cost sulfur cathodes usually exhibit poor cycle performances. Here, we propose gelatinized starch, a natural biological macromolecule from the food industry as a binder for low cost sulfur cathodes to improve their capacity retention. Compared with PVDF, the starch binder is able to reduce the polarization of the sulfur cathode and enhance its capacity retention. The sulfur cathode with the starch binder exhibits a specific capacity retention of ∼90% at 0.2 C after 200 cycles, which corresponds to a small capacity decay of 0.05% per cycle. It is believed that these improvements result from the high stability of the starch binder in a liquid electrolyte, which can stabilize the structure of the cathode and reduce the irreversible accumulation of the discharge products.