Communication
ChemComm
the electrode. In comparison to shorter alkyl analogs, PDA-6 and PTA-6
exhibit two redox couples with small DEps. PDA-6 displays reversible
electrochromic behavior as the neutral, colorless polymer turns green
as the radical cation (PDA-6+ꢁ) and marigold as the dication (PDA-62+)
are generated. The ability to visually identify the state of charge of the
cathode material could be useful in transparent EES devices. Due to
the fast kinetics of the two electron transfers and the 100 nm thick
film, PDA-6 can be charged and discharged at rates up to 1000 C
without an appreciable loss in capacity. The polymer displayed
exceptional stability (499% retention) when cycled only around the
first couple. When the polymer is fully oxidized to PDA-62+, there are
two distinct voltage plateaus and the film retains 92% of the initial
capacity of 165 mA h gꢀ1 after 100 cycles. These findings indicate the
potential usage of PDA-6 as a cathode material in thin-film batteries
that combines the high capacity of batteries with the high power of
supercapacitors. Investigation is currently underway to use the poly-
mers on high surface area electrodes for 3D and flexible batteries.
We are grateful to the Office of Naval Research (N00014-14-1-
0551), and the NSF IGERT program (DGE-0903653) for funding.
Notes and references
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+
2+
+
ꢁ
ꢁ
PDA-6 /PDA-6 couple than the PDA-6/PDA-6 couple (Fig. 3a).
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´
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˜
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ˇ´
ˇ
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Chem. Commun.
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