Title: Understanding the Effect of Cation Disorder on the Voltage Profile of Lithium Transition-Metal Oxides

Abstract

Cation disorder is a phenomenon that is becoming increasingly important for the design of high-energy lithium transition metal oxide cathodes (LiMO 2 ) for Li-ion batteries. Disordered Li-excess rocksalts have recently been shown to achieve high reversible capacity, while in operando cation disorder has been observed in a large class of ordered compounds. The voltage slope (dVdxLi) is a critical quantity for the design of cation-disordered rocksalts, as it controls the Li capacity accessible at voltages below the stability limit of the electrolyte (~4.5-4.7 V). In this study, we develop a lattice model based on first principles to understand and quantify the voltage slope of cation-disordered LiMO 2 . We show that cation disorder increases the voltage slope of Li transition metal oxides by creating a statistical distribution of transition metal environments around Li sites, as well as by allowing Li occupation of high-voltage tetrahedral sites. We further demonstrate that the voltage slope increase upon disorder is generally smaller for high-voltage transition metals than for low-voltage transition metals due to a more effective screening of Li-M interactions by oxygen electrons. Short-range order in practical disordered compounds is found to further mitigate the voltage slope increase upon disorder. Finally, our analysismore » shows that the additional high-voltage tetrahedral capacity induced by disorder is smaller in Li-excess compounds than in stoichiometric LiMO 2 compounds.« less

Authors:

Abdellahi, Aziz ^[1]; Urban, Alexander ^[2]; Dacek, Stephen ^[1]; Ceder, Gerbrand ^[2]

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+ Show Author Affiliations

1. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02141, United States
2. Department of Materials Science and Engineering, UC Berkeley, Berkeley, California 94720, United States, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States

Publication Date:

Thu Jul 28 00:00:00 EDT 2016

Research Org.:

Univ. of California, Berkeley, CA (United States); Energy Frontier Research Centers (EFRC) (United States). Northeastern Center for Chemical Energy Storage (NECCES); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

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

OSTI Identifier:

1275964

Alternate Identifier(s):

OSTI ID: 1288659; OSTI ID: 1454481

Grant/Contract Number:  

SC0012583; SC0001294; AC02-05CH11231

Resource Type:

Published Article

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Name: Chemistry of Materials Journal Volume: 28 Journal Issue: 15; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE