Rewiring electrochemical energy storage on the macroscale via architectural design
Debra R. Rolison
Any future success in the global effort to shift energy usage away from fossil fuels requires energy storage, with electrochemical energy storage in batteries and electrochemical capacitors (ECs) figuring prominently. Energy researchers are now rethinking the requisite multifunction―mass and charge transport, electronic and ionic conductivity, and electron-transfer kinetics―in light of architectural design in three dimensions [1–3] where the use of “nothing” (void space) and deliberate disorder are critical components . When we functionalize carbon nanofoam paper with nanoscale MnOx coatings, we create air cathodes that provide both effective O2-reduction activity (fuel-cell function; ORR) and O2-independent pulse-power capabilities via a capacitive-delivery mechanism (electrochemical-capacitor function; delivering Farads per cm–2 of device over 10s of seconds) [5,6]. For Zn-based batteries, we addressed the Zn “dendrite problem”, which limits battery cycle life, using a radically redesigned 3D Zn sponge architecture. The interconnected Zn sponge retains an inner core of conductive metal throughout cycling that facilitates long-range electronic conductivity and provides more uniform current distribution—two properties needed for high depth-of-discharge (specific energy) and long-term, dendrite-free cycling (battery function). Our efforts to develop these electrode architectures and to bring them together within a fully rechargeable Zn–air cell will be described.
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 J.C. Lytle, J.M. Wallace, M.B. Sassin, A.J. Barrow, J.W. Long, J.L. Dysart, C.H. Renninger, M.P. Saunders, N.L. Brandell, and D.R. Rolison, Energy Environ. Sci. 2011, 4, 1913–1925.
 J.W. Long, C.N. Chervin, N.W. Kucko, E.S. Nelson, and D.R. Rolison, Adv. Energy Mater. 2013, 3, 584.
 C.N. Chervin, J.W. Long, N.L. Brandell, J.M. Wallace, N.W. Kucko, and D.R. Rolison, J. Power Sources 2012, 207, 191.
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