Using waste face masks and batteries to make better batteries

A UNSW SMaRT Centre research study has developed a method of how to recover useful materials from waste face masks and spent batteries to make better new batteries, transforming these wastes into valuable feedstock for remanufacturing.

Published in Elsevier ScienceDirect's Journal of Environmental Chemical Engineering, researchers developed a process to engineer a dual-modified lithium-sulfur battery (Li-S) using the waste materials from respiratory masks and spent batteries.

Li-S batteries are considered one of the most promising next-generation battery technologies because they can potentially store much more energy than conventional lithium-ion batteries. However, two major problems have limited their commercial adoption:

• Lithium dendrite formation on the anode, which reduces battery life and safety.
• The polysulfide shuttle effect, where sulfur-containing compounds move between the battery electrodes, causing capacity loss and poor performance.

Instead of addressing only one problem, the researchers tackled both challenges simultaneously by modifying both the anode and the cathode using materials made from waste resources.

Waste Stream 1: Used Respiratory Masks

Discarded single-use respiratory masks were converted into activated carbon using a microwave-assisted process. The resulting carbon achieved:

• 2407 m²/g surface area
• High porosity
• Excellent ability to trap lithium polysulfides inside the cathode.

Waste Stream 2: End-of-Life Zn-C Batteries

Zinc recovered from spent zinc-carbon batteries was used to create a protective Zn-based Artificial Solid Electrolyte Interphase (ASEI) on the lithium metal anode. The ASEI layer:

• Regulated lithium-ion transport
• Suppressed dendrite growth
• Reduced polysulfide crossover
• Improved anode stability.

Read the study

Key Findings

High Battery Capacity - the dual-modified battery achieved:

• 1180 mAh g⁻¹ specific capacity
• At 0.1C.

Excellent Long-Term Stability - after 400 cycles at 0.5C:

• Modified battery retained 78% of initial capacity
• Untreated battery retained only 42%.

Improved Battery Durability -the combined cathode and anode modifications:

• Reduced polysulfide shuttling
• Prevented dendrite formation
• Extended cycle life
• Improved electrochemical stability.

Scalable Manufacturing - the researchers used:

• Microwave-assisted processing for the cathode
• Immersion coating for the anode.

Both approaches are relatively simple and scalable for larger-scale production.