Designing Li₄Ti₅O₁₂/LiMn₂O₄ Cells: Negative-to-Positive Ratio and Electrolyte

Journal Article · 15 May 2023 · Journal of the Electrochemical Society

DOI: https://doi.org/10.1149/1945-7111/acd304 · OSTI ID:1984217

Ha, Yeyoung ; Trask, Stephen E. ; Zhang, Yicheng; Jansen, Andrew N.; Burrell, Anthony

Li₄Ti₅O12/LiMn2O₄ (LTO/LMO) system is a promising candidate for behind-the-meter storage (BTMS) applications due to its critical-material-free chemistry exhibiting good safety and long lifetime. In this paper we design LTO/LMO cells to mitigate their major degradation mechanism, loss of Li inventory, and improve their long-term cyclability. First, LMO electrodes with different loadings (2.61, 3.29, and 4.26 mAh cm^-2) are paired with an LTO electrode (3.35 mAh cm^-2) to create varying negative-to-positive ratios (N/P>1, =1, and <1). Additionally, conventional ethylene carbonate (EC)/ethyl methyl carbonate (EMC) mixture electrolyte and safety enhanced EC-only electrolyte are examined. We show that storing additional Li inventory in the cathode (i.e., using a thicker electrode and having N/P<1) is a convenient method to enhance the capacity retention of LTO/LMO cells, but only if the electrode utilization is not limited by the Li⁺ ion transport. For systems that suffer from limited transport properties, prelithiating the anode will be more effective since LTO (~165 mAh g^-1_LTO) can store the same amount of capacity using less material compared to LMO (~100 mAh g^-1_LMO). In this work, we demonstrate how the electrolyte properties and the electrode thickness of LTO/LMO cells can be designed to enhance their performance.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Vehicle Technologies Office (VTO)
• Grant/Contract Number: AC36-08GO28308; AC02-06CH11357
• OSTI ID: 1984217
• Alternate ID(s): OSTI ID: 2217468
• Report Number(s): NREL/JA--5K00-85221; {UUID:476e87c4-b4b5-45e1-a492-51e31d1c8849,MainId:85994,MainAdminId:69700,"Journal ID: ISSN 0013-4651"}
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 5 Vol. 170; ISSN 0013-4651
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English