Sulfurized polyacrylonitrile is suggested to contain S
n
(
n
≤ 4) and shows good electrochemical performance in carbonate electrolytes for lithium sulfur batteries. However inferior results in ether electrolytes suggest that high solubility of Li
2
S
n
(
n
≤ 4) trumps the limited redox conversion, leading to dissolution and shuttling. Here, we introduce a small amount of selenium in sulfurized polyacrylonitrile to accelerate the redox conversion, delivering excellent performance in both carbonate and ether electrolytes, including high reversible capacity (1300 mA h g
−1
at 0.2 A g
−1
), 84% active material utilization and high rate (capacity up to 900 mA h g
−1
at 10 A g
−1
). These cathodes can undergo 800 cycles with nearly 100% Coulombic efficiency and ultralow 0.029% capacity decay per cycle. Polysulfide dissolution is successfully suppressed by enhanced reaction kinetics. This work demonstrates an ether compatible sulfur cathode involving intermediate Li
2
S
n
(
n
≤ 4), attractive rate and cycling performance, and a promising solution towards applicable lithium-sulfur batteries.
The ithium-sulfur battery stands as one of the most promising successors of traditional lithium-ion batteries due to its super high theoretical energy density, but practical application still suffers from the shuttle effect arising from soluble intermediate polysulfides. Here, we report SnO2 as a chemical adsorbent for polysulfides. As an interlayer between the cathode and separator, SnO2 gives better results to prevent the polysulfides from diffusing to the lithium anode than as a modifier of the carbon matrix directly. The lithium-sulfur battery with an SnO2 interlayer delivers an initial reversible capacity of 996 mA h g(-1) and retains 832 mA h g(-1) at the 100(th) discharge at 0.5 C, with a fading rate of only 0.19% per cycle. The improvements benefit from the quasi-open space provided by the interlayer configuration for the diffused sulfur species, which can largely relieve the loss of active substances caused by the volume effect during the lithiation/delithiation process.
Oxygen‐rich carbon material is successfully fabricated from a porous carbon and evaluated as anode for sodium‐ion battery. With the strategy of optimal combination of fast surface redox reaction and reversible intercalation, the oxygen‐rich carbon anode exhibits a large reversible capacity (447 mAh g−1 at 0.2 A g−1), high rate capability (172 mAh g−1 at 20 A g−1), and excellent cycling stability.
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