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

Abstract

Summary 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. Here, 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. We found that the protection layer with 25 wt% lignin leads to the best overall electrochemical performance of Li‐S batteries during charging/discharging at 0.5°C and 1C rate (1C = 1,675 mA g−1) 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−1 for 1C and 0.5C, respectively) are demonstrated. Besides, Li‐S cells with 25 wt% lignin/MWCNT composite protection layer also exhibited great rate capability, of which the specific capacities at 0.1C, 0.5C, 1C, and 2C were 1150, 913, 824, and 637 mAh g−1, respectively. 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.

Freestanding graphitic carbon nitride‐based carbon nanotubes hybrid membrane as electrode for lithium/polysulfides batteries

“…However, the synthesis and processing involved may often be tedious and time‐consuming. In addition, functionalizing the separator or interlayers has been shown to provide a polysulfide shuttle barrier and improve electron transport, but they also bring extra weight and reduce the overall energy density. Recently, the introductions of polar inorganic compounds into carbon‐based materials, such as metal oxides, metal sulfides, metal nitrides, and metal carbides have also been extensively investigated to bond with polysulfides species.…”

Influence of TiO 2 /TiC composite materials with different crystal structures on the electrochemical properties as sulfur‐loaded matrix for lithium‐sulfur batteries

“…[1][2][3] However, the application has been limited for a long time due to electronic insulation of sulfur-active material, volume expansion during cycling and the high dissolvability in the electrolyte and shuttle effect of the discharge intermediate polysulfides (Li 2 Sn, 4 ≤ n ≤ 8). [4][5][6][7] These issues result in a fast discharge capacity fading, poor high rate charge and discharge performance and undesirable cycle life. At the moment, a large number of researches have revealed that sulfur composite electrode materials can most effectively debase the impact of these issues.…”

“…Lithium‐sulfur batteries are identified as promising energy storage device in future owing to their high theoretical specific capacity (1675 mAh g −1 ), low cost and environmental friendliness . However, the application has been limited for a long time due to electronic insulation of sulfur‐active material, volume expansion during cycling and the high dissolvability in the electrolyte and shuttle effect of the discharge intermediate polysulfides (Li 2 Sn, 4 ≤ n ≤ 8) . These issues result in a fast discharge capacity fading, poor high rate charge and discharge performance and undesirable cycle life.…”

Lignin biopolymer: the material of choice for advanced lithium-based batteries

“…It can be carbonized at high temperatures; to avoid shuttling, MWCNTs were mixed and the impacts were investigated. When 25 wt% of lignosulphonate (LS) lignin was employed in MWCNTs as a protection layer, minimum capacity decay with a higher initial discharge capacity at a cycling rate of 0.5 and 1C was observed, 104 whereas using LS as a binder to replace the conventional PVDF binder that cannot mitigate the shuttling effect leading to low electrochemical performance, a higher specic discharge capacity of $1307 mA h g À1 at a cycling rate of 0.1C was achieved in comparison to PVDF (706 mA h g À1 ) with a capacity retention of 71.9%. 105 Nonetheless, the encapsulation of sulphur within the microporous carbon network derived from commercially available lignin (Fig.…”