Ultrafast and Long-Cycle Stable Aluminum Polyphenylene Batteries.

Rechargeable aluminum-ion batteries (RAIBs) are highly sought after due to the extremely high resource reserves and theoretical capacity (2980 mA h/g) of metal aluminum. However, the lack of ideal cathode materials restricts its practical advancement. Here, we report a conductive polymer, polyphenylene, which is produced by the polymerization of molecular benzene as a cathode material for RAIBs with an excellent electrochemical performance. In electrochemical redox, polyphenylene is oxidized and loses electrons to form radical cations [ C 6 H 4 ] 3 n + and intercalates with [AlCl 4 ] - anion to achieve electrical neutrality and realize electrochemical energy storage. The stable structure of polyphenylene makes its discharge specific capacity reach 92 mA h/g at 100 mA/g; the discharge plateau is about 1.4 V and exhibits an excellent rate performance and long cycle stability. Under the super high current density of 10 A/g (∼85 C), the charging can be completed in 25 s, and the capacities have almost no decay after 30,000 cycles. Aluminum polyphenylene batteries have the potential to be used as low-cost, easy-to-process, lightweight, and high-capacity superfast rechargeable batteries for large-scale stationary power storage.