Abstract
High voltage spinel cathode LiNi0.5Mn1.5O4 (LNMO) offers higher energy density and competitive cost compared to traditional cathodes in lithium-ion batteries, making it a promising option for high-performance battery applications. However, the fast capacity decay in the full cell hindered further commercialization. Therefore, it is crucial to evaluate lithium inventory across the entire battery system. The Li inventory evolution upon cycling in the LNMO-Graphite pouch cell is systematically studied by developing Lithium quantification methods on cathode, anode, and electrolyte. All the active and inactive Li in the system after cycling were quantified. The findings reveal that active Li loss is a primary factor contributing to capacity decay, stemming from unstable anode interphase caused by crosstalk. This crosstalk primarily originates from electrolyte degradation on the cathode under high-voltage operation, leading to increased moisture and acidity, subsequently corroding the anode interphase. In response, two approaches, including an Aluminum Oxide (Al2O3) surface coating layer on the cathode and Lithium difluoro(oxalato)borate (LiDFOB) electrolyte additives, are evaluated systematically, resulting in cycling stability enhancement. This study offers a quantitative approach to understanding the Li inventory loss in the LNMO-Gr system, providing unique insights and guidance into identifying critical bottlenecks for developing high voltage (>4.4V) lithium battery technology.
Published Version
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