Polyimide-Coated Glass Microfiber as Polysulfide Perm-Selective Separator for High-Performance Lithium-Sulphur Batteries

Abstract

Although numerous research efforts have been made for the last two decades, the chronic problems of lithium-sulphur batteries (LSBs), i.e., polysulfide shuttling of active sulphur material and surface passivation of the lithium metal anode, still impede their practical application. In order to mitigate these issues, we utilized polyimide functionalized glass microfibers (PI-GF) as a functional separator. The water-soluble precursor enabled the formation of a homogenous thin coating on the surface of the glass microfiber (GF) membrane with the potential to scale and fine-tune: the PI-GF was prepared by simple dipping of commercial GF into an aqueous solution of poly(amic acid), (PAA), followed by thermal imidization. We found that a tiny amount of polyimide (PI) of 0.5 wt.% is more than enough to endow the GF separator with useful capabilities, both retarding polysulfide migration. Combined with a free-standing microporous carbon cloth-sulphur composite cathode, the PI-GF-based LSB cell exhibits a stable cycling over 120 cycles at a current density of 1 mA/cm2 and an areal sulphur loading of 2 mgS/cm2 with only a marginal capacity loss of 0.099%/cycle. This corresponds to an improvement in cycle stability by 200%, specific capacity by 16.4%, and capacity loss per cycle by 45% as compared to those of the cell without PI coating. Our study revealed that a simple but synergistic combination of porous carbon supporting material and functional separator enabled us to achieve high-performance LSBs, but could also pave the way for the development of practical LSBs using the commercially viable method without using complicated synthesis or harmful and expensive chemicals.

Metal–Organic Framework Separator as a Polyselenide Filter for High-Performance Lithium–Selenium Batteries

“…The voltage polarization of the cell with a PCN separator was stable over 500 h. As a control, we performed the cycling experiment using the symmetric cell with a polypropylene separator. The voltage polarization of the polypropylene separator cell was stable up to 290 h and then gradually decreased in voltage because of the short circuit. − After 290 h, we observed the overpotential (circled, Figure C,D) in the polypropylene separator due to the growth of lithium dendrites − from the uneven plating behavior of lithium, , which penetrated the polypropylene separator . The short-circuit of the cell with the polypropylene separator further explained the low lithium transference number.…”

Carbon-Based Hybrid Interlayer to Anchor the Shuttling of Polysulfides for High-Performance Lithium–Sulfur Batteries

“…The role of C_IL is to trap the dissolved polysulfide and create an additional electron pathway as an upper current collector for the Li–S cell (Figure b). The micro-glass fiber mat provides a 3D interconnected network of a randomly arranged porous silicate microfiber range in between 0.1 and 1.9 μm with a thickness of 260 μm and pore size of 1.2 μm that are much higher than those of the polypropylene (Celgard 2400) separator . It also has higher electrolyte permeability and thermal stability as compared to polypropylene.…”

“…The micro-glass fiber mat provides a 3D interconnected network of a randomly arranged porous silicate microfiber range in between 0.1 and 1.9 μm with a thickness of 260 μm and pore size of 1.2 μm that are much higher than those of the polypropylene (Celgard 2400) separator. 31 It also has higher electrolyte permeability and thermal stability as compared to polypropylene. The carbonized glucose provided the agglomerated mesoporous carbon morphology, 32 coating over and in between the fibers that helps in the trapping of polysulfides and makes it ideal for the investigation.…”

Polyimide separators for rechargeable batteries

“…The Cheng group verified their results by utilizing a hot-pressed electrospun PI separator [124]. Apart from pure PI, other materials have been mixed with PI to achieve even better performance [125][126][127][128][129]. Wang et al prepared a composite separator by loading graphdiyne onto PI [130].…”