LiCoO 2 -Based Fiber Cathodes for Electrospun Full Cell Li-ion Batteries
Here, particle/polymer electrospinning was used to prepare fiber mat cathodes containing LiCoO 2 nanoparticles, carbon powder, and poly(vinylidene fluoride) for Li-ion batteries. The fibers had a high LiCoO 2 particle content (70 wt%) which allowed for a high gravimetric capacity of 90 mAh g -1 (corresponding to 128 mAh g$-1\atop{LiCoO2}$) at 0.1C (1C = 274 mAh g$-1\atop{LiCoO2}$). Cathode performance was stable in a half cell with 78% capacity retention over 200 cycles at 0.5C. Unlike previous work on electrospun LiCoO 2 nanofibers prepared using sol-gel chemistry and high temperature processing, the particle/polymer fiber mat cathodes reported here were made thick with a high fiber volume fraction for high areal and volumetric capacities at fast charge/discharge rates (e.g., 0.81 mAh cm -2 and 62 mAh cm -3 at 2C) which were much greater than that of a slurry cast cathode of the same composition (0.004 mAh cm -2 and 0.30 mAh cm -3 at 2C). Full cells containing a LiCoO 2 /C/PVDF fiber mat cathode and C/PVDF fiber mat anode were also prepared and characterized. These electrospun batteries exhibited a high energy density of 144 Wh kg -1 at 0.1C and an areal capacity of 1.03 mAh cm -2 at 1C. The excellent performance of the electrospun particle/polymer cathodes and anodes is attributed to electrolyte penetration throughout the 3D fiber electrode mats, a large electrode/electrolyte interfacial area, and short Li + transport pathways between the electrolyte and active material nanoparticles in the radial fiber direction.