Preparation of highly porous sulfur bodies and the use of excess electrolytes are common strategies to improve sulfur utilization. However, the flooded electrolyte limits the actual energy density of lithium-sulfur pouch batteries.
Lu Zhouguang of Southern University of Science and Technology, Shi Bin, State Key Laboratory of Special Chemical Power Supplyet al. proposed a new type of Fe034co0.33ni0.33S2 is used as the main body of sulfur to achieve excellent electrochemical performance of AH-grade Li-S whole cell under the condition of 2 L mg-1 poor electrolyte.
Fig.1 Schematic diagram of the discharge process of the fcn111@s GC cathode
This is done by combining the electrochemical activity Fe034co0.33ni0.The 33S2 backbone (FCN111) was coupled with graphene and multi-walled carbon nanotubes to composite with S8 (fcn111@s GC) to design an embedding-conversion hybrid cathode material. Kelvin probe force microscopy shows that the FCN surface contains a positive charge of about 70 mV, which enhances binding to polysulfides through Lewis acid-base interactions.
In addition, in 18-2.Within a voltage window of 1 V, the FCN111 can also store lithium ions, thus further contributing to the capacity. What's more, the use of electrolyte in utility pouch cells is greatly reduced due to the additional Li-S binding and sulfur vacancies of FCN111.
Figure 2 Button battery performance
So, in 15 ma cm-2 (≈0.7 C), the fcn111@s GC cathode provided an initial capacity of 1350 mAh g-1, which remained at 879 mAh g-1 after 300 cycles. Even if the sulfur load is increased to 6 mg cm-2, it can still be increased at 15 ma cm-2（≈0.2 c) at a current density of 1029 mAh g-1 and a retention capacity of 841 mAh g-1 after 100 cycles.
Furthermore, the button type whole cell based on the fcn111@s GC composite cathode was 1. at an E-S ratio of 2 ul mg 1Energy densities of 394 and 267 Wh kg-1 were achieved at currents of 5 and 4 mA cm-2 (1 C). Pouch battery in 1The specific energy of 300 wh kg-1 was maintained after 60 cycles of 5 mA cm-2.
Figure 3 Pouch battery performance
ternary transition metal sulfide as high real energy cathode for lithium–sulfur pouch cell under lean electrolyte conditions. small methods 2021. doi: 10.1002/smtd.202101402