A Multifunctional Interlayer Enhancing Water Tolerance in Rechargeable Lithium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Water as a protic impurity significantly degrades lithium battery performance and safety.
• Current methods for reducing water content in electrolytes are energy-intensive.
• Stabilizing electrode interfaces and preventing electrolyte decomposition are crucial for battery longevity.

Purpose of the Study:

• To develop a multifunctional interlayer for lithium battery separators that mitigates water-induced degradation.
• To enhance the safety and cycling stability of lithium batteries using a novel sepiolite-based material.
• To investigate the impurity absorption capabilities and thermal stability of the modified separator.

Main Methods:

• Utilizing dehydrated sepiolite on a commercial polypropylene separator (Sep@PP) as a multifunctional interlayer.
• Characterizing the sepiolite interlayer's active sites (Si-O-Si, Mg-OH2, Mg-OH) for impurity absorption.
• Testing the performance of Sep@PP separators in LiNi0.5Mn1.5O4 (LNMO)//Li and LiNi0.6Mn0.2Co0.2O2 (NCM622)//Li battery cells under various conditions.

Main Results:

• The Sep@PP separator effectively absorbed water (H2O), hydrogen fluoride (HF), and transition metal ions.
• LNMO//Li cells with Sep@PP showed excellent cycling stability, retaining 84.1% capacity over 500 cycles, even with 1200 ppm water.
• NCM622//Li cells demonstrated superior stability at 55 °C, maintaining 72.3% capacity after 200 cycles.
• The sepiolite interlayer significantly enhanced thermal stability, reducing risks of thermal runaway.

Conclusions:

• Dehydrated sepiolite on polypropylene separators is a promising strategy for mitigating water hazards in lithium batteries.
• The Sep@PP separator improves battery cycling stability, safety, and tolerance to moisture.
• This approach offers a novel and effective method for enhancing the performance and reliability of modern battery technologies.