Constructing Multi-functional Composite Separator of PVDF-HFP/h-BN supported Co-CNF membrane for Lithium-Sulfur Batteries

Functional design of separator has been proved to be one of the most efficient methods to improve electrochemical performances of lithium-sulfur batteries. In this work, a multifunctional separator with gradual...

Construction of KB@ZIF-8/PP Composite Separator for Lithium–Sulfur Batteries with Enhanced Electrochemical Performance

Lithium–sulfur batteries (LSBs) have attracted wide attention, but the shuttle effect of polysulfide hinders their further practical application. Herein, we develop a new strategy to construct a Ketjen black@zeolite imidazole framework-8/polypropylene composite separator. Such a separator consists of Ketjen black (KB), zeolite imidazole framework-8 (ZIF-8) and polypropylene (PP) with a low coating load of 0.06 mg cm−2 and is denoted as KB@ZIF-8/PP. KB@ZIF-8/PP can absorb polysulfides because of the Lewis acid-base interaction between ZIF-8 and polysulfides. This interaction can reduce the dissolution of polysulfides and suppress the shuttle effect, thereby enhancing the electrochemical performance of the battery. When tested at a current density of 0.1 C, an LSB with a KB@ZIF-8/PP separator exhibits low polarization and achieves a high initial capacity of 1235.6 mAh/g and a high capacity retention rate of 59.27% after 100 cycles.

Tissue Paper-based Composite Separator Using Nano-SiO2 Hybrid Crosslinked Polymer Electrolyte as Coating Layer For Lithium Ion Battery With Superior Security and Cycle Stability

With the development of energy-storage devices, separator is encountered by several challenges including adequate safety, higher current density and superior stability. Tissue paper, composed of packed cellulose fibers, possesses lower production cost, more easily accessibility, superior wettability and outstanding thermostability, thus being prospective as a substrate of high performance separator. To address structure collapse phenomenon occurred in conventional coating layer after long term electrolyte swelling, nano-SiO2 hybrid crosslinked network was constructed on tissue paper through chemical reactions between polymer poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and hyperbranched polyethyleneimine (PEI) in this work. The influences of crosslinking degree on physical properties and electrochemical performance were studied thoroughly. It can be found that when the crosslinking ratio of PVDF-HFP and PEI fixed at 10:1, the crosslinked composite separator displays excellent electrolyte uptake and wettability, superior ionic conductivity, better interfacial compatibility as well as higher Li+ transference number (0.56), thus offering battery with prominent rate capabilities. Besides, this crosslinked composite separator exhibits satisfying dimensional stability even treated at 250 oC, better flame retardancy, enhanced mechanical behavior, wider electrochemical window and outstanding cycle stability. Accordingly, tissue paper-based crosslinked composite separator can meet higher requirements put forward by high power lithium ion battery.