LiCoO2-Based Fiber Cathodes for Electrospun Full Cell Li-ion Batteries

Particle/polymer electrospinning was used to prepare fiber mat cathodes containing LiCoO2 nano particles, carbon powder, and poly(vinylidene fluoride) for Li-ion batteries. The fibers had a high LiCoO2 particle content (70 wt%) which allowed for a high gravimetric capacity of 90 mAh g(-1) (corresponding to 128 mAh(LiCoO2)(-1),0 2, 1 at 0.1C (1C = 274 mAh g(LiCoO2)(-1)). Cathode performance was stable in a half cell with 78% capacity retention over 200 cycles at 0.5C. Unlike previous work on electrospun LiCoO2 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 LiCoO2/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. (C) 2016 Elsevier Ltd. All rights reserved.