Abstract
Nowadays, lithium-sulfur (Li-S) batteries have been considered as one of the most promising next-generation rechargeable batteries, owing to their high theoretical specific capacity of 1672 mAh g−1, high energy density of 2600 Wh kg−1, low-cost and abundant resources. However, the commercial application of Li-S batteries is still hindered by several problems, including insulativity of element sulfur, dissolution of polysulfides and large volume expansion. In addition, sulfur cathodes need be paired with metallic lithium, which tends to form dendrites on the anode surface during cycling resulting in safety problems. Therefore, fully lithiated state of sulfur-lithium sulfide (Li2S) is advantageous over sulfur, because it can paired with metal-free anodes (e.g. graphite, silicon and Sn) avoiding safety problems. In addition, Li2S shows a high theoretical specific capacity of 1166 mAh g−1 and a high melting point of 938°C. Moreover, when Li2S convers to S companying with volume shrinkage, which will not only creates enough space for volumetric expansion but also makes the structure more stable. However, similar to sulfur cathode, low conductivity of Li2S, low active material loading and polysulfide dissolution Li2S limit application of Li2S for high performance batteries. Consequently, it is important to introduce Li2S into three dimensional conductive matrix/host for high performance. Herein, we construct a 3D conductive network with high loading Li2S through a facile liquid solution-evaporation. The 3D conductive network not only possesses a hierarchical architecture with abundant macroporous channels and exhibits a high surface area, which provides enough reaction sites to load and stabilize high-loading Li2S, but also improves the electronic conductivity of Li2S and demonstrates pronounced electrochemical performance with enhanced cycle stability and a good capacity retention.
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