Lithium Lactate Modified Polyolefin Separators for High-Performance Lithium Metal Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Polyolefin separators limit lithium ion (Li+) mobility, hindering lithium metal battery adoption.
• Existing strategies struggle to balance Li+ transference, anion transference, and conductivity.
• High energy density batteries require improved separator performance.

Purpose of the Study:

• To develop high-performance separators for stable lithium metal battery operation.
• To overcome the limitations of conventional polyolefin separators.
• To enhance lithium ion (Li+) flux and suppress dendrite formation.

Main Methods:

• Coating polyolefin separators with lactic acid lithium, dopamine hydrochloride, and triethanolamine.
• Characterizing separator properties: wettability, electrolyte uptake, ionic conductivity.
• Evaluating separator performance in lithium metal batteries (LMBs) under cycling conditions.
• Utilizing Density Functional Theory (DFT) for mechanistic analysis.

Main Results:

• The modified DL2-PP separator demonstrated stable LMB operation at 1 C for 600 cycles with 92% capacity retention.
• Achieved ionic conductivity of 1.2 mS cm-1 and a Li+ transference number of 0.68.
• The polar modification layer improved electrolyte wettability and uptake.
• Negatively charged moieties effectively increased Li+ transference without reducing overall conductivity.
• DFT calculations elucidated the mechanism for uniform Li+ flux and deposition.

Conclusions:

• The novel separator modification strategy significantly enhances lithium metal battery performance and safety.
• The ultrathin polar layer promotes selective and uniform Li+ transport, mitigating dendrite growth.
• This approach offers a promising solution for next-generation high energy density batteries.