Polyoxometalates/Active Carbon Thin Separator for Improving Cycle Performance of Lithium–Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries have great potential for the next generation of energy-storage devices owing to their high theoretical energy density. However, the polysulfides’ shuttling effect seriously degraded the cycle stability and capacity and hindered their commercial applications. Here, we design and fabricate a bifunctional composite separator including a polypropylene (PP) matrix layer and Keggin polyoxometalate [PW12O40]3–/Super P composite retarding layer by utilizing the Coulombic repulsion between polyanion and polysulfides. Such a binary composite separator shows the effects in enhancing the Coulombic efficiency and cycling stability. Compared with the polypropylene (PP) matrix separator, the capacity is improved by 41% after 120 cycles when using the PW12/Super P separator. It is the first time that the polyoxometalate (POM) matrix is used as a bifunctional separator for lithium–sulfur batteries, demonstrating the promise of POM-based separators in reducing the shuttling effect of Li–S battery.

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…K 3 PW 12 O 40 ‐based polyoxotungstates have been employed in the lithium‐sulfur battery cathode . Bifunctional composite separator consisting of [PW 12 O 40 ] 3− polyoxometalate and polypropylene is fabricated to mitigate the polysulfide shuttling issue, resulting in a 40% improvement after 120 cycles compared with the conventional polypropylene‐based separation . Apart from the application in lithium‐ion and lithium‐sulfur batteries, the polyoxotungstates have been employed in lithium‐oxygen batteries.…”

“…Because the polyoxometalates are rich in Lewis acidic and basic sites and have already shown applications in lithium‐ion batteries and lithium‐sulfur batteries including their dissolution mitigation capabilities, we believe that the polyoxometalates will show applications in other types of energy storage systems such as calcium‐, aluminum‐, magnesium‐, and fluorine‐based batteries.…”

“…227 Bifunctional composite separator consisting of [PW 12 O 40 ] 3− polyoxometalate and polypropylene is fabricated to mitigate the polysulfide shuttling issue, resulting in a 40% improvement after 120 cycles compared with the conventional polypropylene-based separation. 228 Apart from the application in lithium-ion and lithium-sulfur batteries, the polyoxotungstates have been employed in lithium-oxygen batteries. For instance, α-SiW 12 O 40 4− can facilitate the transformation of O 2 to Li 2 O 2 in lithium-oxygen batteries, serving as a good candidate for the redox mediators.…”

“…By leveraging the electrochromic properties of Well-Dawson-type polyoxometalates based on K 10 231 The electrochromic properties are available in K 6 P 2 W 18 O 62 when it is combined with TiO 2 nanowires, resulting in excellent switching and transmittance properties. 232 Polyoxotungstates have been employed in a number of energy conversion and storage applications 36,43,228,[233][234][235][236][237][238][239][240][241][242] and sensors. 145,[243][244][245][246][247] 6 | POLYOXOMOLYBDATE Molybdenum trioxide with the formula MoO 3 has been applied as catalysts and synthesizing agent, and its polyoxometalate counterpart polyoxomolybdate has been widely studied to modulate their electronic and optoelectronic properties for energy conversion and storage applications.…”

“…301 Novel structures are prepared by hybridizing polyoxometalates and other substrates, 302,303 while polyoxomolybdates are employed in a number of applications owing to their versatile properties. 4,49,89,228,[304][305][306][307][308][309][310][311] 7 | POLYOXOVANADATE Vanadium oxide enjoys high coefficient of thermal resistance and has been applied to vanadium redox batteries and various catalysts. [312][313][314] Vanadium-containing polyoxometalates have been used in dye-sensitized solar cells via as cosensitizers 84 and as precursors for solar conversion photoanode synthesis such as BiVO 4 .…”