Electrochemical improvement in high-voltage Li-ion batteries by electrospinning a small amount of nano-Al2O3 in P(MVE-MA)/P(VdF-HFP)-blended gel electrolyte

To improve the comprehensive performance of fibrous membrane based on poly(methyl vinyl ether-alt-maleic anhydride) P(MVE-MA)- and poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-HFP)-blended copolymers, a small amount of nano-Al 2 O 3 was doped by electrospinning technique to apply for high-energy-density cathode material of nickel-rich LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) based Li-ion battery. The results indicated that the electrospinning membrane and corresponding gel polymer electrolyte (GPE) only doped with 3.0 wt.% nano-Al 2 O 3 presented the proper structure and delivered the best electrochemical characterization. Due to the uniform distribution of nanoparticles on the fibers with higher density, the specific surface area and porosity of the fiber membrane were increased, leading to the improved fracture stress of 172.0 MPa for the membrane and ionic conductivity of 2.1 × 10 −3 S cm −1 for the GPE at room temperature. Contributed from the proper pore structure and the enhanced interfacial stability, the capacity retention of 89.4% was achieved for the Li/GPE/NCA coin cell after 200 cycles in the voltage range of 3.0 V and 4.3 V under room temperature using the GPE doped with 3 wt.% Al 2 O 3 , compared with that of 63.6% for the GPE without nanoparticles. Similarly, the discharge capacity of the coin cell under 7 C rate (123.2 mAh g −1 ) maintained 65% of that at 0.3 C (189.4 mAh g −1 ), showing good rate performance of the developed GPE. Therefore, the significant improvement in electrochemical stability of the GPE achieved by doping a small number of nanoparticles provided a simple and feasible solution for the development of high-energy-density Li-ion batteries.