High loading sulfur cathode is a vital ingredient for the application of high-energy-density Li-S battery. However, the traditional PVDF binder with inherent defects, such as relatively weak adhesion, inferior Li + conduction, and poor polysulfides adsorption, is not suitable for sulfur cathode, especially at high sulfur loading. Herein, the multifunctional LiPAA/PVA binder with crosslinked three-dimensional structure was proposed to substitute PVDF binder. Benefiting from the effective polysulfides adsorption and successful conduction of electron and Li + , the sulfur cathode with LiPAA/PVA binder exhibited superior rate and cycle performance. Even at high sulfur loading of 4.0 mg/cm 2 , the LiPAA/PVA based cathode also shows a highest areal capacity of 3.03 mA h/cm 2 , matching the requirement for high energy density of Li-S battery. Additionally, owing to the low price and water solubility of LiPAA and PVA , the fabrication of LiPAA/PVA based cathode could be finished through an low-cost and environmentally friendly process, demonstrating the potential of LiPAA/PVA binder to realize high loading sulfur cathode in the field of large-scale Li-S battery.
The lithium-sulfur (Li-S) battery has received widespread attention because of the high theoretical energy density and inexpensive raw material. However, some issues still restrict its commercialization, including the shuttle effect, the lithium dendrite growth and low safety, etc. In this work, a PMMA-LLZO/PP/AB multifunctional separator was designed and facilely prepared to overcome these problems. A composite dense layer of the PMMA and LLZO sheets with excellent interface stability was coated on one side of the PP separator to face lithium metal anode, which can inhibit the lithium dendrites growth and increase the safety. Meanwhile, this composite coating possesses high affinity with the liquid electrolyte and the soluble polysulfides, which can improve the ionic conductivity, effectively adsorb the polysulfides. An acetylene black (AB) layer was further coated on the other side of the PP separator to not only act as an electron conductor but also adsorb and hinder the migration of lithium polysulfides. The co-modified PMMA-LLZO/PP/AB separator displays remarkable electrochemical performances and an excellent thermal stability. The cell with the co-modified separator exhibits high specific capacities of 1456 mAh g −1 at 0.1 C and 969 mAh g −1 at 1.0 C, and retains a capacity of 413 mAh g −1 after 500 cycles, corresponding to a retention of 42.6% as well as a low decay of 0.114%/cycle. Especially, the cell with the multifunctional separator also displays a high capacity and a low decay even for a high sulfur mass loading cathode of 2.5–3.0 mg cm −2 or at a high temperature of 60 °C. The co-modified multifunctional separator has great application potential in the high-performance Li-S battery.
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