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Title: Extended Interfacial Stability Through Simple Acid Rinsing in a Li-Rich Oxide Cathode Material

Abstract

Layered Li-rich Ni, Mn, Co (NMC) oxide cathodes in Li-ion batteries provide high specific capacities (>250 mAh/g) via O-redox at high voltages. However, associated high-voltage interfacial degradation processes require strategies for effective electrode surface passivation. Here, we show that an acidic surface treatment of a Li-rich NMC layered oxide cathode material leads to a substantial suppression of CO 2 and O 2 evolution, ~90% and ~100% respectively, during the first charge up to 4.8 V vs. Li +/0. CO 2 suppression is related to Li 2CO 3 removal as well as effective surface passivation against electrolyte degradation. This treatment does not result in any loss of discharge capacity and provides superior long-term cycling and rate performance compared to as-received, untreated materials. We also quantify the extent of lattice oxygen participation in charge compensation (“O-redox”) during Li + removal by a novel ex-situ acid titration. Our results indicate that the peroxo-like species resulting from O-redox originate on the surface at least 300 mV earlier than the activation plateau region around 4.5 V. X-ray photoelectron spectra and Mn -L X-ray absorption spectra of the cathode powders reveal a Li + deficiency and a partial reduction of Mn ions on the surface ofmore » the acid-treated material. More interestingly, although the irreversible oxygen evolution is greatly suppressed through the surface treatment, our O K-edge resonant inelastic X-ray scattering shows the lattice O-redox behavior largely sustained. The acidic treatment, therefore, only optimizes the surface of the Li-rich material and almost eliminates the irreversible gas evolution, leading to improved cycling and rate performance. This work therefore presents a simple yet effective approach to passivate cathode surfaces against interfacial instabilities during high-voltage battery operation.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1594933
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
ChemRxiv
Additional Journal Information:
Related Information: preprint; Journal ID: ISSN 2573-2293
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
Li-ion batteries; Li-rich NMC Oxides; Interfacial degradation; Anion Redox; O-redox; DEMSOEMS; Cathode Electrolyte Interface; Surface passivation

Citation Formats

Ramakrishnan, Srinivasan, Park, Byungchun, Wu, Jue, Yang, Wanli, and McCloskey, Bryan. Extended Interfacial Stability Through Simple Acid Rinsing in a Li-Rich Oxide Cathode Material. United States: N. p., 2019. Web. doi:10.26434/chemrxiv.9962471.v1.
Ramakrishnan, Srinivasan, Park, Byungchun, Wu, Jue, Yang, Wanli, & McCloskey, Bryan. Extended Interfacial Stability Through Simple Acid Rinsing in a Li-Rich Oxide Cathode Material. United States. doi:10.26434/chemrxiv.9962471.v1.
Ramakrishnan, Srinivasan, Park, Byungchun, Wu, Jue, Yang, Wanli, and McCloskey, Bryan. Wed . "Extended Interfacial Stability Through Simple Acid Rinsing in a Li-Rich Oxide Cathode Material". United States. doi:10.26434/chemrxiv.9962471.v1. https://www.osti.gov/servlets/purl/1594933.
@article{osti_1594933,
title = {Extended Interfacial Stability Through Simple Acid Rinsing in a Li-Rich Oxide Cathode Material},
author = {Ramakrishnan, Srinivasan and Park, Byungchun and Wu, Jue and Yang, Wanli and McCloskey, Bryan},
abstractNote = {Layered Li-rich Ni, Mn, Co (NMC) oxide cathodes in Li-ion batteries provide high specific capacities (>250 mAh/g) via O-redox at high voltages. However, associated high-voltage interfacial degradation processes require strategies for effective electrode surface passivation. Here, we show that an acidic surface treatment of a Li-rich NMC layered oxide cathode material leads to a substantial suppression of CO2 and O2 evolution, ~90% and ~100% respectively, during the first charge up to 4.8 V vs. Li+/0. CO2 suppression is related to Li2CO3 removal as well as effective surface passivation against electrolyte degradation. This treatment does not result in any loss of discharge capacity and provides superior long-term cycling and rate performance compared to as-received, untreated materials. We also quantify the extent of lattice oxygen participation in charge compensation (“O-redox”) during Li+ removal by a novel ex-situ acid titration. Our results indicate that the peroxo-like species resulting from O-redox originate on the surface at least 300 mV earlier than the activation plateau region around 4.5 V. X-ray photoelectron spectra and Mn-L X-ray absorption spectra of the cathode powders reveal a Li+ deficiency and a partial reduction of Mn ions on the surface of the acid-treated material. More interestingly, although the irreversible oxygen evolution is greatly suppressed through the surface treatment, our O K-edge resonant inelastic X-ray scattering shows the lattice O-redox behavior largely sustained. The acidic treatment, therefore, only optimizes the surface of the Li-rich material and almost eliminates the irreversible gas evolution, leading to improved cycling and rate performance. This work therefore presents a simple yet effective approach to passivate cathode surfaces against interfacial instabilities during high-voltage battery operation.},
doi = {10.26434/chemrxiv.9962471.v1},
journal = {ChemRxiv},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {10}
}

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