Aramid nanofiber reinforced cellulose paper for high-safety lithium-ion batteries

Lithium dendrite growth greatly threaten the safety of lithium-ion batteries by piercing the separators. Fabricating a lithium-dendrite-suppressing separator with high mechanical strength, thermal stability and ionic conductivity features is a challenging work. Herein, aramid nanofibers (ANFs) is used as novel nanofiller to reinforce commercial cellulose paper via simple vacuum filtration method. The reinforced cellulose paper (ANF-CP) shows robust mechanical strength, super thermal stability and excellent electrolyte wettability and ionic conductivity, demonstrating its great potential as separators. The ANF-CP exhibits outstanding compatibility to lithium anode (voltage gap of ~ 4.0 mV upon 3000 h), which indicate the functions of homogeneous plating/stripping of lithium and demonstrate its lithium-dendrite-suppressing property. The LiFePO4/Li cells with ANF-CP separator exhibit a high discharge capacity of ~ 122.4 mAh g−1 at 5C with exceptional cycling stability. Besides, the mechanism and phenomenon of dendrite suppressing are also confirmed by DFT simulation calculation and the continuous charging and discharging experiments of LiFePO4/graphite full-cells. All the results demonstrate the ANF-CP may have great potential application in energy storage systems, and thus this work may promote the application of cellulose and aramid fibers.