Enhancing the Electrode Gravimetric Capacity of Li1.2Mn0.4Ti0.4O2 Cathode Using Interfacial Carbon Deposition and Carbon Nanotube-Mediated Electrical Percolation

Jianan Xu; Shripad Patil; Krishna Prasad Koirala; Weiyin Chen; Astrid Campos-Mata; Chongmin Wang; Soumyabrata Roy; Jagjit Nanda; Pulickel M Ajayan

doi:10.1021/acsami.3c04805

Enhancing the Electrode Gravimetric Capacity of Li_1.2Mn_0.4Ti_0.4O₂ Cathode Using Interfacial Carbon Deposition and Carbon Nanotube-Mediated Electrical Percolation

ACS Appl Mater Interfaces. 2023 Jul 5;15(26):31711-31719. doi: 10.1021/acsami.3c04805. Epub 2023 Jun 20.

Authors

Jianan Xu¹, Shripad Patil^{2

3}, Krishna Prasad Koirala⁴, Weiyin Chen⁵, Astrid Campos-Mata¹, Chongmin Wang⁶, Soumyabrata Roy¹, Jagjit Nanda^{3

7}, Pulickel M Ajayan¹

Affiliations

¹ Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States.
² Bredesen Center for Interdisciplinary Research and Education, University of Tennessee Knoxville, Knoxville, Tennessee 37996, United States.
³ Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States.
⁴ Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
⁵ Department of Chemistry, Rice University, Houston, Texas 77005, United States.
⁶ Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
⁷ Applied Energy Division SLAC National Laboratory 2575, Sand Hill Road, Menlo Park, California 94025, United States.

PMID: 37339110
DOI: 10.1021/acsami.3c04805

Abstract

Mn-based cation-disordered rocksalt oxides (Mn-DRX) are emerging as promising cathode materials for next-generation Li-ion batteries due to their high specific capacities and cobalt- and nickel-free characteristic. However, to reach the usable capacity, solid-state synthesized Mn-DRX materials require activation via postsynthetic ball milling, typically incorporating more than 20 wt % conductive carbon that adversely reduces the electrode-level gravimetric capacity. To address this issue, we first deposit amorphous carbon on the surface of the Li_1.2Mn_0.4Ti_0.4O₂ (LMTO) particles to increase the electrical conductivity by 5 orders of magnitude. Although the cathode material gravimetric first charge capacity reaches 180 mAh/g, its highly irreversible behavior leads to a first discharge capacity of 70 mAh/g. Subsequently, to ensure a good electrical percolation network, the LMTO material is ball-milled with a multiwall carbon nanotube (CNT) to obtain a 78.7 wt % LMTO active material loading in the cathode electrode (LMTO-CNT). As a result, a 210 mAh/g cathode electrode gravimetric first charge and 165 mAh/g first discharge capacity values are obtained, compared to the respective capacity values of 222 and 155 mAh/g for the LMTO material ball-milled with 20 wt % SuperP C65 electrode (LMTO-SP). After 50 cycles, LMTO-CNT delivers a 121 mAh/g electrode gravimetric discharge capacity, largely outperforming the value of 44 mAh/g of LMTO-SP. Our study demonstrates that while ball milling is necessary to achieve a significant amount of capacity of LMTO, a careful selection of additives, such as CNT, effectively reduces the required carbon quantity to achieve a higher electrode gravimetric discharge capacity.

Keywords: CNT ball-milling additive; Li1.2Mn0.4Ti0.4O2 cathode materials; electrical percolation pathway; electrode gravimetric capacity; vapor-phase carbon coating.