Functional binder for high-performance Li–O2 batteries

In the present work, the polypyrrole (PPy), as a conductive polymer, is for the first time introduced as functional binder of air cathode for lithium–oxygen batteries by a self-assembly process. Most of the carbon particles in the air cathode are found to be uniformly congregated with each other by the in-situ polymerized conductive polymer PPy, which affords a lower electrode resistance and higher electrode integrity. Replacement of the conventional inactive PVDF binder by the functional conductive polymer in the cathode, which not only acts as the binder and conductor, but also functions as a host for fast Li-ion insertion/extraction, has demonstrated its effectiveness in improving the cycle-efficiency, specific capacity, rate capability and cycling stability of the lithium–oxygen cells. In comparison with the PVDF binder, the PPy/C cathode demonstrates ∼2.6 times (2626.3 mA h g−1vs. 1005.8 mA h g−1) and ∼5.3 times (1816.4 mA h g−1vs. 345.6 mA h g−1) higher capacity at 0.1 mA cm−2 and 0.5 mA cm−2 respectively.

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► Conductive polymer PPy was introduced as functional binder for cathode of Li–O2 cell.
► PPy binding cathode demonstrates lower contact/charge-transfer resistance than PVDF.
► PPy promotes simultaneous Li+/e− transfer in cathode during the discharge/charge.
► PPy/C improves efficiency, specific capacity, rate capability and cycling stability.
► Cathode with PPy binder demonstrates a better integrity than the conventional PVDF.