Xiaoke Luo,Di Wang,Shiyi Liu,Hailong Yan,Jinbing Cheng,Yang Lu,Deyang Zhang,Huan Pang
The redox reactions occurring at positive electrode of the lithium-sulfur (Li-S) batteries involve several key electrocatalytic processes that significantly impact the overall performance of the electrochemical energy storage system. This study presents a heterogeneous catalytic composite material composed of CoSe quantum dots (QDs) integrated with Sn 3 O 4 nanosheets, which enhances the overall ionic conductivity and accessibility of active sites within the cathode. This controlled migration effectively traps polysulfides within the cathode, reducing their dissolution into the electrolyte and mitigating the shuttle effect. Li-S batteries incorporating CoSe QDs/Sn 3 O 4 porous carbon nanofibers (PCNFs) demonstrate a high discharge capacity of 1596.9 mAh g −1 at 0.1 C, along with remarkable cycling stability, achieving 1500 cycles at 2 C with a minimal capacity decay of 0.024 % per cycle. Even under a high sulfur loading conditions of 8.61 mg cm −2 and a low electrolyte to sulfur ratio of approximately 4.6 μL mg −1 , the CoSe QDs/Sn 3 O 4 PCNFs cathode delivers an initial discharge-specific capacity of 732.0 mAh g −1 at 0.2 C. Through this method, we accomplished the size control and uniform distribution of CoSe QDs, and this method can be extended to the synthesis of other metal oxide and metal sulfide QDs, offering a novel idea for the application of QDs in polysulfide catalysis.
Di Wang,Ya Yang,Shiyi Liu,Hailong Yan,Jinbing Cheng,Yang Lu,Yongsong Luo,Hui Ying Yang
Lithium-sulfur (Li–S) batteries face significant challenges, including capacity fading and restricted rate performance, primarily caused by the passivation of active materials, the polysulfide shuttle phenomenon, and sluggish redox reactions. To address these issues, a composite material comprising CoSe quantum dots (QDs)/NiO PCNFs (porous carbon nanofibers) has been designed and synthesized. This innovative design enhances the accessibility of active sites, which play a vital role in effectively anchoring and converting lithium polysulfides (LiPSs). The CoSe quantum dots (QDs) embedded in NiO porous carbon nanofibers (PCNFs) leveraged the synergistic interactions between their components to achieve exceptional cyclic stability, maintaining an ultra-low capacity decay rate of 0.034 % per cycle over 500 cycles at a current density of 2 C. The heterostructure and the built-in electric field (BIEF) work in concert to mitigate the polysulfide shuttle effect and promote faster electron and lithium-ion transport. This advanced architecture presents a promising strategy for enhancing the energy density and cycle lifespan of Li–S batteries, advancing their potential for practical implementation.
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