High-density catalytic heterostructures strung by buried-in carbon tube network as monolithic holey host for endurable Li-S batteries

• In-situ cascade of carbon nanotube network with NiCoP/CoP heterojunction grains as S cathode host is proposed. • The high-density distribution of phosphide heterostructures maximizes the exposure of catalytic sites for polysulfides. • The effective hiding of CNT skeletons can avoid the loose and uneven deposition of S-based species. • NiCoP/CoP@C ternary host with monolithic holey texture endows high-loading LSBs with excellent cycling stability. The development of Li-S batteries (LSBs) is plagued by the unreasonable integration of adsorption-catalysis-conduction functional modules. Heterojunction domains are expected to achieve the job-sharing catalysis and adsorption effects, which are however degraded by the loose discrete distribution and insufficient exposure of catalyst. Herein, we propose a unique catalysis-conduction configuration for S cathode host, featured by in-situ cascade of carbon nanotube (CNT) network with polar NiCoP/CoP heterojunction grains strung on each CNT (NiCoP/CoP@C). The compact and high-density distribution of phosphide heterostructures maximizes the exposure of catalytic sites to synergically enhance the conversion kinetics of lithium polysulfides. It also enables an effective hiding of CNT skeletons to avoid the loose and uneven deposition of S-based species without the compromise of interconnected conduction pathways and electrode robustness. NiCoP/CoP@C ternary host with monolithic holey texture endows LSBs with excellent cycling stability (with capacity decay rate of merely 0.029% per cycle over 1000 cycles) under high sulfur utilization and high rate (at 2C). Even with a high sulfur loading (7.5 mg/cm 2 ) and a low E/S ratio (7.2 µL/mg), the reversible capacity is still as high as 562 mAh/g and 4.21 mAh/cm 2 after 300 cycles. The combination of low E/S ratio of 5.0 μL/mg and high S loading of 5.0 mg/cm 2 still enables the durability of Li-S batteries for at least 360 cycles at 1C and highly reversible capacity close to 600 mAh/g at 0.5C.