Title: Impact of Multifunctional Bimetallic Materials on Lithium Battery Electrochemistry

Abstract

Electric energy storage devices such as batteries are complex systems comprised of a variety of materials with each playing separate yet interactive roles, complicated by length scale interactions occurring from the molecular to the mesoscale. Thus, addressing specific battery issues such as functional capacity requires a comprehensive perspective initiating with atomic level concepts. For example, the electroactive materials which contribute to the functional capacity in a battery comprise approximately 30% or less of the total device mass. Thus, the design and implementation of multifunctional materials can conceptually reduce or eliminate the contribution of passive materials to the size and mass of the final system. Material multi-functionality can be achieved through appropriate material design on the atomic level resulting in bimetallic electroactive materials where one metal cation forms mesoscale conductive networks upon discharge while the other metal cation can contribute to atomic level structure and net functional secondary capacity, a device level issue. Specifically, this Account provides insight into the multi-mechanism electrochemical redox processes of bimetallic cathode materials based on transition metal oxides (MM’O) or phosphorous oxides (MM’PO) where M = Ag and M’ = V or Fe. One discharge process can be described as reduction-displacement where Ag⁺ is reduced tomore » Ag⁰ and displaced from the parent structure. This reduction-displacement reaction in silver-containing bimetallic electrodes allows for the in-situ formation of a conductive network, enhancing the electrochemical performance of the electrode and reducing or eliminating the need for conductive additives. A second discharge process occurs through the reduction of the second transition metal, V or Fe, where the oxidation state of the metal center is reduced and lithium cations are inserted into the structure. As both metal centers contribute to the functional capacity, determining the kinetically and thermodynamically preferred reduction processes at various states of discharge is critical to elucidating the mechanism. Specific advanced in-situ and ex-situ characterization techniques are conducive to gaining insight regarding the electrochemical behavior of these multifunctional materials over multiple length scales. At the material level, optical microscopy, scanning electron microscopy, and local conductivity measurement via a nanoprobe can track the discharge mechanism of an isolated single particle. At the mesoscale electrode level, in-situ data from synchrotron based energy dispersive X-ray diffraction (EDXRD) within fully intact steel batteries can be used to spatially map the distribution of silver metal generated through reduction displacement as a function of discharge depth and discharge rate. As illustrated here, appropriate design of materials with multiple electrochemically active metal centers and properties tuned through strategically conceptualized materials synthesis may provide a path toward the next generation of high energy content electroactive materials and systems. In conclusion, full understanding of the multiple electrochemical mechanisms can be achieved only by utilizing advanced characterization tools over multiple length scales.« less

Authors:

Durham, Jessica L. ^[1]; Poyraz, Altug S. ^[2]; Takeuchi, Esther S. ^[3]; Marschilok, Amy C. ^[4]; Takeuchi, Kenneth J. ^[4]

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+ Show Author Affiliations

1. Stony Brook Univ., NY (United States). Dept. of Chemistry
2. Brookhaven National Lab. (BNL), Upton, NY (United States). Energy Sciences Directorate
3. Stony Brook Univ., NY (United States). Dept. of Chemistry; Brookhaven National Lab. (BNL), Upton, NY (United States). Energy Sciences Directorate; Stony Brook Univ., NY (United States). Dept. of Materials Science and Engineering
4. Stony Brook Univ., NY (United States). Dept. of Chemistry; Stony Brook Univ., NY (United States). Dept. of Materials Science and Engineering

Publication Date:

Fri Aug 26 00:00:00 EDT 2016

Research Org.:

Brookhaven National Lab. (BNL), Upton, NY (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Mesoscale Transport Properties (m2M)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1336208

Report Number(s):

BNL-113226-2016-JA
Journal ID: ISSN 0001-4842

Grant/Contract Number:  

SC001270; AC02-98CH10886; SC0012673

Resource Type:

Accepted Manuscript

Journal Name:

Accounts of Chemical Research

Additional Journal Information:

Journal Volume: 49; Journal Issue: 9; Journal ID: ISSN 0001-4842

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; lithium; battery electrochemistry; mesoscale