Practical lithium–organic batteries enabled by an n-type conducting polymer

 

Currently, the widespread use of portable electronic devices demands batteries with higher storage capacities and longer lifetimes. Among the various options available on the market, lithium-ion batteries (LIBs) stand out due to their high energy storage capacity and long service life. However, these devices are typically composed of inorganic materials derived from limited mineral resources, which leads to negative environmental impacts. For this reason, research efforts have been directed toward finding more sustainable and environmentally friendly alternatives.

Scientists from several Chinese universities have developed organic lithium batteries using an n-type conductive polymer, poly(benzodifurandione) (PBFDO). PBFDO exhibits excellent ionic and electronic transport properties, high electrical conductivity (>2000 S/cm), low solubility in liquid electrolytes, and thermal structural stability up to 200 °C. The researchers constructed polymer cathodes with an ultrahigh mass loading of up to 206 mg/cm², achieving a specific capacity of 42 mAh/cm². In addition, 2.5 Ah lithium-organic pouch cells were fabricated with an energy density of 255 Wh/kg, comparable to that of commercial lithium-ion batteries.

The results reveal π–π stacking of the (010) planes with interplanar distances of 0.34 nm and lamellar stacking of the (100) planes with interplanar distances of 1.04 nm. Within these stacked structures, channels containing a large number of carbonyl groups are formed, which are attributed to enabling efficient lithium transport. These cells demonstrated strong cycling stability, resistance to nail penetration without explosion or fire, and efficient performance across an extreme temperature range (−70 °C to 80 °C). The flexibility of the PBFDO cathodes was also highlighted, making them suitable for applications in portable electronics. Furthermore, the energy storage mechanism of PBFDO was investigated, showing that carbonyl groups act as active sites for lithium-ion storage.

This work opens the door to the use of n-type conductive polymers as electrodes in LIBs, since the type of charge carriers (electrons) helps maintain charge balance when Li⁺ is inserted into the electrode, in contrast to p-type conductive polymers whose charge carriers (holes) make charge balance more difficult.

More information at: NATURE