Modulating the Coordination Environment of Lithium Bonds for High Performance Polymer Electrolyte Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Next-generation lithium metal batteries demand polymer electrolytes with superior ionic conductivity and mechanical strength.
• Lithium bond formation between functional groups and lithium ions (Li+) critically impacts polymer electrolyte performance, a factor often overlooked.
• Developing stable and efficient polymer electrolytes is crucial for advancing lithium metal battery technology.

Purpose of the Study:

• To design and synthesize a novel lithium bond-enriched polymer gel electrolyte (PAEV) for high-performance lithium metal batteries.
• To investigate the influence of lithium bond manipulation on ionic conductivity and mechanical properties of polymer electrolytes.
• To explore the effect of the tailored coordination environment of Li+ on the formation of stable solid-electrolyte interphases.

Main Methods:

• Copolymerization of 4-acryloylmorpholine (ACMO) and 1-vinyl-3-ethyl imidazolium bis(trifluoromethylsulfonyl)imide ([VEIM][TFSI]) in [EMIM][TFSI] with LiFSI.
• Regulation of lithium bonds via Li+ coordination number and hydrogen bonding interactions.
• Characterization of ionic conductivity and mechanical properties of the developed polymer gel electrolyte.
• Evaluation of the PAEV electrolyte in Li/LiFePO4 (LFP) batteries.

Main Results:

• A lithium bond-enriched polymer gel (PAEV) was successfully synthesized, exhibiting tunable ionic conductivity and mechanical properties.
• The lithium bonds formed between LiFSI and carbonyl groups in PACMO were effectively regulated by Li+ coordination and hydrogen bonding.
• Uniform LiF and Li3N layers were formed on the Li metal surface, facilitating Li+ nucleation and deposition.
• The PAEV electrolyte enabled Li/LiFePO4 batteries to achieve high capacities of 124 mA h g-1 at 25 °C and 152 mA h g-1 at 50 °C.

Conclusions:

• Lithium bond manipulation is a viable strategy for developing advanced polymer electrolytes.
• The PAEV electrolyte demonstrates significant potential for high-performance lithium metal batteries.
• This work provides a new pathway for designing polymer electrolytes with tailored properties for energy storage applications.