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Title: The role of electronic and ionic conductivities in the rate performance of tunnel structured manganese oxides in Li-ion batteries

Single nanowires of two manganese oxide polymorphs (α-MnO 2 and todorokite manganese oxide), which display a controlled size variation in terms of their square structural tunnels, were isolated onto nanofabricated platforms using dielectrophoresis. This platform allowed for the measurement of the electronic conductivity of these manganese oxides, which was found to be higher in α-MnO 2 as compared to that of the todorokite phase by a factor of similar to 46. Despite this observation of substantially higher electronic conductivity in α-MnO 2, the todorokite manganese oxide exhibited better electrochemical rate performance as a Li-ion battery cathode. The relationship between this electrochemical performance, the electronic conductivities of the manganese oxides, and their reported ionic conductivities is discussed for the first time, clearly revealing that the rate performance of these materials is limited by their Li + diffusivity, and not by their electronic conductivity. This result reveals important new insights relevant for improving the power density of manganese oxides, which have shown promise as a low-cost, abundant, and safe alternative for next-generation cathode materials. Moreover, the presented experimental approach is suitable for assessing a broader family of one-dimensional electrode active materials (in terms of their electronic and ionic conductivities) for both Li-ionmore » batteries and for electrochemical systems utilizing charge-carrying ions beyond Li +.« less
 [1] ;  [2] ;  [2] ;  [1]
  1. Drexel Univ., Philadelphia, PA (United States)
  2. Virginia Commonwealth Univ., Richmond, VA (United States)
Publication Date:
Accepted Manuscript
Journal Name:
APL Materials
Additional Journal Information:
Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2166-532X
American Institute of Physics (AIP)
Research Org:
National Nuclear Security Administration, North Las Vegas, NV (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); Drexel University
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 25 ENERGY STORAGE; lithium batteries; electrochemical properties; hybrid supercapacitor; carbon nanotubes; challenges; cathode; intercalation; lifepo4; phase; layer; nanowires; manganese; electrodes; ionic conductivity
OSTI Identifier: