Anchoring Carbon Spheres on Titanium Dioxide Modified Commercial Polyethylene (PE) Separator to Suppress Lithium Dendrites for Lithium Metal Batteries.

Abstract

Lithium dendrites are easily generated for excessively-solved lithium ions (Li+ ) inside the lithium metal batteries, which will lead serious safety issues.In this experiment, carbon spheres (CS) are successfully anchored on TiO2 (CS@TiO2 ) in the hydrothermal polymerization, which is filtrated on the commercial PE separator (CS@TiO2 @PE). Thenegative charge in CS can suppress random diffusion of anions through electrostatic interactions. Density functional theory (DFT) calculations show that CS contributes to the desolvation of Li+ , thereby increasing the migration rate of Li+ . Furthermore, TiO2 exhibits high affinity to liquid electrolytes and acts as a physical barrier to lithium dendrite formation. CS@TiO2 is a combination of the advantages of CS and TiO2 . As results, the Li+ transference number of the CS@TiO2 @PE separator can be promoted to 0.63. The Li||Li cell with the CS@TiO2 @PE separator exhibits a stable cycle performance for more than 600h and lower polarization voltage (17mV) at 1mA cm-2 . The coulombic efficiency (CE) of the Li||Cu cells employe the CS@TiO2 @PE separator is 81.63% over 130 cycles. The discharge capacity of LiFePO4 ||Li cells based on the CS@TiO2 @PE separator is 1.73 mAh (capacity retention = 91.53% after 260 cycles). Thus, the CS@TiO2 layer inhibits lithium dendrite formation.