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Operando Calorimetry Informs the Origin of Rapid Rate Performance in Microwave-Prepared TiNb2O7 Electrodes

preprint
submitted on 30.10.2020, 17:31 and posted on 02.11.2020, 07:59 by Sun Woong Baek, Kira E. Wyckoff, Danielle M. Butts, Jadon Bienz, AMPOL LIKITCHATCHAWANKUN, Molleigh B. Preefer, Matevz Frajnkovic, Bruce S. dunn, Ram Seshadri, Laurent Pilon
The shear-phase compound TiNb2O7 has recently emerged as a safe and high-volumetric density replacement for graphite anodes in lithium ion batteries. An appealing feature of TiNb2O7 is that it retains capacity even at high cycling rates. Here we demonstrate that phase pure and crystalline TiNb2O7 can be rapidly prepared using a high-temperature microwave synthesis method. Studies of the charging and discharging of this material, including through operando calorimetry, permit key thermodynamic parameters to be revealed. The nature of heat generation is dominated by Joule heating, which sensitively changes as the conductivity of the electrode increases with increasing lithiation. The enthalpy of mixing, obtained from operando calorimetry, is found to be small across the different degrees of lithiation pointing to the high rate of lithium ion diffusion at the origin of rapid rate performance.

Funding

EFRC Center for Synthetic Control Across Length-scales for Advancing Rechargeables (SCALAR)

Basic Energy Sciences

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Email Address of Submitting Author

bbaekssun@ucla.edu

Institution

University of California Los Angeles

Country

United States of America

ORCID For Submitting Author

0000-0002-8784-5844

Declaration of Conflict of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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