2019 July - Our Paper Published on Wiley International Journal of Energy Research

Improving lithium‐sulfur battery performance with lignin reinforced MWCNT protection layer

https://doi.org/10.1002/er.4680

We employed lignin, a byproduct during high‐quality bleached paper manufacturing, to replace a portion of MWCNT in the protection layer to reduce cost and enhance surface properties of pristine MWCNT protection layers.

Multi‐walled carbon nanotube (MWCNT) protection layers have previously been used to trap polysulfides and suppress the shuttle effect in lithium sulfur (Li‐S) batteries, leading to significant performance improvement. While the MWCNT is inherently highly conductive and mechanically strong, the cost can be significant and in turn hampered wider application of MWCNT protection layers.

We found that the protection layer with 25 wt% lignin leads to the best overall electrochemical performance of Li‐S batteries during charging/discharging among various weight‐ratios of lignin/MWCNT, and a low decay rate (0.20% per cycle) and high initial capacity (1342 mA g−1 and 1437 mA g−1for 1C and 0.5C, respectively) are demonstrated.

Charge/dsicharge profile of Li‐S cells with different weight ratio protection layer cycle at (A) 1C rate; (B) 0.5C rate at 1st cycle

Discharge capacity curve of Li‐S cells with 0, 25, and 50 wt% lignin/MWCNT protection layer, charge/discharge at 0.5C rate

The enhanced electrochemical stability and performance of Li‐S batteries can be attributed to strengthened polysulfide trapping and improved lithium ion transport with lignin reinforced MWCNT protection layers. We showcased an economic approach to extend cycle life and improve rate capability of Li‐S batteries