Ether-Modified Nonflammable Phosphate Enabling Anion-Rich Electrolyte for High-Voltage Lithium Metal Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 39506393.
- Also identified by DOI 10.1002/adma.202312302.
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Abstract
Phosphate-based localized high-concentration electrolytes (LHCE) feature high flame retardant and satisfactory cathodic stability for lithium metal batteries. However, stable cycling of those electrolytes at ultra-high upper cut-off voltages for long-term stability remains challenging. Herein, an ether-modified phosphate, diethyl (2-methoxy ethoxy) methylphosphonate (DMEP), is designed for high-voltage applications. The ether modification enhances the stability of the Li<sup>+</sup>-DMEP-FSI<sup>-</sup> coordination structure, promoting the formation of cation-anion aggregates (AGG) dominated solvation structure, which favors the generation of LiF-rich cathode electrolyte interphase layers compared to triethyl phosphate (TEP)-based LHCE. Consequently, cathode degradation, including transition-metal dissolution and electrode cracking, is well-suppressed. The LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> (NCM811)||Li full cells using DMEP-based LHCEs show more than 90.7% capacity retention at an ultrahigh upper cut-off voltage of 4.7 V after 100 cycles. Notably, DMEP-LHCE exhibits enhanced safety than that of TEP-LHCE, suggesting its versatility and potential for next-generation lithium metal batteries.