N/O dual-doped hollow carbon microspheres constructed by holey nanosheet shells as large-grain cathode host for high loading Li-S batteries

Lithium-sulfur (Li-S) battery is one of the most prospective energy storage systems beyond lithium ion battery technologies owing to its super-high theoretical energy density and low cost. However, the dissolution of polysulfide intermediates and low level of sulfur loading still retard the practical application of Li-S batteries. Here, a self-sacrifice templating strategy is reported to synthesize N/O dual-doped hollow carbon microspheres (HCMs) by carbonization of polydopamine coating carbon nitride hollow spheres. The HCM host is constructed by holey nanosheets in shell with a large surface area (873 m(2)/g) and pore volume (4.84 cm(3)/g), high N/O doping contents (5.36 and 6.99 atom%). Benefiting from the confinement effect, wetting capability, lithiophilic adsorption and catalytic conversion, HCMs-S cathode enables a reversible capacity around 900 mAh/g at 1-2 C and a retention capacity of 530 mAh/g after 900 cycles. HCMs-S also enables an endurance of high mass and areal S loadings (90% and 4.84 mg/cm(2)) with a reversible capacity around 700 mAh/g. Long-term and high-rate cycling does not degrade the homogeneous deposition of nanostructured Li2S at cathode side and dendrite-free Li plating at anode side. This work demonstrates a facile approach to micro-sized C-S grains with desirable three-dimensional architecture composed of two-dimensional building blocks and interconnected mass/charge transport channels for high loading Li-S batteries.