Pie-like electrode design for high-energy density lithium–sulfur batteries

Owing to the overwhelming advantage in energy density, lithium–sulfur (Li–S) battery is a promising next-generation electrochemical energy storage system. Despite many efforts in pursuing long cycle life, relatively little emphasis has been placed on increasing the areal energy density. Herein, we have designed and developed a ‘pie' structured electrode, which provides an excellent balance between gravimetric and areal energy densities. Combining lotus root-like multichannel carbon nanofibers ‘filling' and amino-functionalized graphene ‘crust', the free-standing paper electrode (S mass loading: 3.6 mg cm(−2)) delivers high specific capacity of 1,314 mAh g(−1) (4.7 mAh cm(−2)) at 0.1 C (0.6 mA cm(−2)) accompanied with good cycling stability. Moreover, the areal capacity can be further boosted to more than 8 mAh cm(−2) by stacking three layers of paper electrodes with S mass loading of 10.8 mg cm(−2).