LFO modified separator for the initial anode irreversibility compensation in lithium-ion rechargeable full cells

Abstract

Lithium-ion batteries (LIBs) dominate portable electronics and electric vehicles for their high energy density and long cycle life. However, a part of active Li loss in the initial charge process for the solid electrolyte interphase (SEI) formation at the anode surface, which reduces the energy density and cycle life of LIBs. Prelithiation attempts have been widely regarded as providing additional active lithium to address this issue. Li5FeO4 (LFO) as a cathode prelithiation additive with high donable lithium ions is very promising. But the residues of the gas release limited its further application due to its low conductivity in the first charge process. Here, we prepared CNT/ Polyacrylonitrile (PAN) /LFO/polypropylene (PP) separator by an electrospinning method, the CNT/PAN/LFO/PP separator can effectively improve cycle performance of LFP batteries, benefiting from Li2O participation in the construction of SEI and higher infiltration rate of the electrolyte resulting in faster interfacial Li+ transfer kinetics. The LFP pouch cell with CNT/PAN/LFO/PP separator can maintain a stable output over 1000 cycles (capacity fade rate per cycle of 0.005 %) with a highercapacity increased by 6.2 %.