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Chemical Engineering

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Battery electrode binder allows easier recycling

| By Scott Jenkins

Recovering valuable metals, such as cobalt and nickel, from used lithium-ion batteries is emerging as a key capability because of anticipated high battery demand and material shortages. Researchers at Lawrence Berkeley National Laboratory (Berkeley, Calif.; have developed a technology for an electrode binder material that facilitates the recovery of valuable metals from used batteries at low cost. Binders are glue-like substances that hold the active materials together within the electrode and maintain its architecture.

To make new batteries, manufacturers process binders with solvents to create a slurry containing all the electrode components, which is then deposited in the desired shape and thickness on electrode sheets. The Berkeley Lab approach was to “design for recycling” in the way the electrode is made.

Known as Quick-Release Binder, the Berkeley Lab product is made from two commercially available polymers, polyacrylic acid (PAA) and polyethylenimine (PEI), that are joined together through a bond between positively charged nitrogen atoms in PEI and negatively charged oxygen atoms in PAA. When the solid binder material is placed in alkaline water containing sodium hydroxide, the sodium ion inserts into the bond site, breaking the two polymers apart. The separated polymers dissolve into the liquid, freeing any electrode components embedded within.

“A battery made with Quick-Release Binder simply needs to be opened, placed in room-temperature alkaline water, and gently shaken,” says project leader Gao Liu, a senior scientist in Berkeley Lab’s Energy Technologies Area. “The separated elements are easily filtered out of the water and air-dried.”

The binder, which contains no PFAS compounds and can be used to make both anodes and cathodes, is about one-tenth the price of two of the most commonly used commercial binders. Past experiments demonstrated that the binder is highly stable at high and low voltages.

The Quick-Release Binder originated from research on lithium-sulfur batteries, which are possible future alternatives to traditional Li-ion batteries, and later applied to Li-ion batteries. The team is now working with Steve Sloop, a battery recycling developer and founder of OnTo Technologies (Budd Lake, N.J.; to build prototype Li-ion batteries with the Quick-Release binder to analyze its performance comprehensively and showcase its functionality.