An interactive organic–inorganic composite interface enables fast ion-transport, low self-discharge and stable storage of lithium battery

Abstract

Lithium batteries have been widely used in various fields, however, further research needs to be conducted to improve their stability and long-term storage performance for the highly active lithium metal anode. Herein, an organic–inorganic composite film composed of polypropylene carbonate (PPC), lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) and Li6.5La3Zr1.5Nb0.5O12 (LLZNO) is fabricated on the lithium foil surface by spin-coating technique to passivate the lithium anode and regulate the ion transport behavior. The Li/CFx battery with the optimized composite film coated lithium anode exhibits excellent discharge capacity (1006.6 mAh/g, 0.1C) and high-rate capability (639.4 mAh/g, 5C), much higher than those of the uncoated Li/CFx battery. The discharge specific capacity remains 521.7 mAh/g at 0.1C after stored at 55 °C for 60 days, corresponding to a monthly self-discharge of 1.87 %, while the battery without coating film has almost failed. Theoretical calculation, Raman mapping and Kelvin probe force microscopy (KPFM) measurements demonstrate that the stable and ion-conductive composite film effectively increases ion channels, regulates ion migration and passivates the Li anode from the corrosion of liquid electrolyte during discharge and storage. Constructing a rational organic–inorganic composite film with high mechanical stability and ionic conductivity on the Li anode surface is a facile and cost-effective strategy to enhance the high-rate and long-term storage performance of Li/CFx battery.