Lithium–sulfur (Li–S) batteries have attracted considerable attention because of their high theoretical energy density. However, poor conductivity and a large volume change in S during cycling, together with a shuttle effect of polysulfides, severely restrict the battery performance, and remain a great challenge. Herein, inspired by a natural dandelion structure, we present a novel biomimetic S-coated carbon nanotube composite consisting of dandelion-like three-dimensional carbon nanotubes coated with S particles on the surface. Carbon nanotubes provide high-speed electron transfer pathways for S during cycling, while the special dandelion-like morphology provides a suitable environment for accommodating the volume change in S upon charge–discharge. The dandelion-like S-coated carbon nanotube-based Li–S batteries exhibit a stable capacity exceeding 760 mAh g−1 after 500 cycles at 0.1 C, along with a Coulombic efficiency as high as 99.9%. Even under repeated rounds of rate-performance measurements, and cycling at different charge versus discharge rates, the batteries retain high capacities and good recovery capabilities. In addition, the proportion of capacitive contribution in the overall capacity is high, indicating a good reversible capacity provided by the composite.
Garnet-type solid electrolytes are promising lithium (Li) ion conductors for all-solid-state batteries. However, their poor compatibilities towards Li metal due to their inherently lithiophobic properties severely hinder their practical application in garnet-based solid-state Li metal batteries (SSLBs). Here, we demonstrated a soldering method to modify the surface of garnet ceramic by forming a thin artificial sulfur layer, which results in a homogeneous and stable Li/solid electrolyte interface. This artificial interface effectively enhances the compatibility between the garnet-type solid electrolyte and the Li metal anode . Consequently, the interfacial resistance of sulfur-coated garnet electrolyte is significantly reduced from 1750 Ω cm 2 to 160 Ω cm 2 based on the electrochemical impedance spectroscopy (EIS) measurements on Li symmetric cells. Besides, the symmetric cell exhibits an excellent lifetime of more than 1100 h at a steady state of voltage hysteresis, which indicates a stable and dendrite-free garnet/Li metal interface . The fabricated Li|garnet|LiCoO 2 SSLB using this novel interfacial treatment delivers a high specific capacity of 126 mAh g −1 and good cycling stability.
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