Final Report: Recycling Rare Earth Metals from Nickel Metal Hydride Batteries

EPA Contract Number: EPD12009
Title: Recycling Rare Earth Metals from Nickel Metal Hydride Batteries
Investigators: Sloop, Steven E
Small Business: OnTo Technology LLC
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: March 1, 2012 through August 31, 2012
Project Amount: $80,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2012) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Innovation in Manufacturing


The purpose of this Phase I Small Business Innovation Research (SBIR) project was to develop safe decommission of nickel metal hydride (NiMH) alkaline batteries and recycling of rare earth elements (REE) from their negative electrode. This Phase I SBIR project developed safe methods of recycling rare earth alloys from used NiMH batteries. Alloys of rare earth metal, nickel and other metals provide functional hydride storage materials that are critical to the operation of NiMH batteries and their applications. The current fleet of hybrid electric vehicles (HEVs) relies on NiMH batteries. The first fleet of vehicles manufactured in the early 2000s will reach recycling age in the 2010¬ís. NiMH represent a billion dollar industry, and the growth will continue in HEVs, grid storage, and consumer electronic applications. Currently, end-of-life NiMH batteries find use as feedstock for stainless steel manufacturing. The practice disposes of the battery safely, but does not recover any rare earth elements and reduces potential benefits for battery rare earth recycling, such as reduction in manufacturing cost and reliance on rare-earth mining. When NiMH is used for stainless steel, battery replacement and its market growth remains reliant on mined rare earth metals. This project decommissioned used NiMH batteries and recycled the rare earth material from electrodes, making them useful for manufacturing new NiMH batteries. This project demonstrated safety and technical feasibility that will be foundational for a new industry aimed at recycling advanced batteries from the growing fleet of HEVs. Successful recycling developed in this proposal provides an economic way for the Nation to conserve critical materials, avoid pollution associated with mining and establish the next generation of industrial infrastructure to serve the growing HEV market.

Summary/Accomplishments (Outputs/Outcomes):

The project developed (1) use of an in-house patent pending process to decommission large format HEV NiMH cells so that they can be disassembled without catching fire, (2) disassemble batteries and separate the anode and cathode compartments, and (3) recycle the REE alloy utilizing low temperature separation methods.


Safe decommission: Large-format NiMH batteries were treated using green-chemical processing techniques. They were opened and negative electrode material was harvested. They did not catch fire when exposed to air, which is observed and expected for the untreated cells. This observation documents the green-chemical decommission process. The treatment successfully eliminated potassium hydroxide, which is a toxic chemical present in the batteries. The process parameters were identified, and allow for reasonable, commercially accessible processes.
Rare earth metal isolation: The project developed separation of rare earth metals from used NiMH batteries. The recovered metals were reduced to a metallic, zero-valent mischmetal. The process model and product is feasible to practice on a commercial scale, including production of mischmetal, which is a marketable product in manufacturing of NiMH batteries.
Commercial Application:
The NiMH battery is the HEV industry standard for performance, safety and price, with historical NiMH cost ~ $200/kWh. There are more than 2 million HEVs in the United States. The feasibility of decommission can be commercially applied to improve safety in transportation and processing for end-of-life, alkaline, metal hydride batteries from small and large products. An HEV pack contains greater than 60kg of rare earth and other metals. The recycling feasibility can be commercially applied to low temperature separation of rare earth metals from NiMH battery residues. Decommission of consumer alkaline batteries is a near-term commercial application. Large commercialization partners are evaluating the process for this application.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this project

Supplemental Keywords:

metal, rare earth metal, alloy, nickel, battery, nickel metal hydride battery, recycle, recycling, hybrid electric vehicle