Honda Motor Company has established a process to reuse rare earth metals extracted from nickel-metal hydride batteries for new nickel-metal hydride batteries to recycle precious resources.
So far, Honda has been extracting an oxide containing rare earth metals from used nickel-metal hydride batteries at the plant of Japan Metals & Chemicals Co., Ltd. (JMC). Now, by applying molten salt electrolysis to this oxide, Honda has succeeded in extracting metallized rare earth that can be used directly as negative-electrode materials for nickel-metal hydride batteries. The rare earth metals extracted in this process has a purity of more than 99% which is as high as that of ordinary traded, newly mined rare earth metals. In addition, the new process enables the extraction of as much as above 80% of rare earth metals contained in nickel-metal hydride battery.
Under the newly established process, the extracted rare earth metals will be supplied from JMC to a battery manufacturer in early March, which will reuse them as negative-electrode materials for nickel-metal hydride batteries for hybrid vehicles. This time, the rare earth metals were extracted from nickel-metal hydride batteries collected from 386 Honda hybrid vehicles that were stored prior to being on sale but became unusable by the Great East Japan Earthquake. As soon as a sufficient volume is secured, Honda will begin applying the same process and recycle rare earth metals extracted from used nickel-metal hydride batteries collected by Honda dealers through battery replacement.
Honda is not the first company to recycle rare earth metals from NiMH batteries. Umicore and Rhodia jointly developed a unique process in 2011.
The main use of NiMH batteries is in rechargeable AA and AAA batteries (typically used in domestic applications such as cordless phones, toys and games), power tools as well as hybrid electric vehicles. A typical NiMH battery will contain some 7% of rare earth elements including cerium, lanthanum, neodymium and praseodymium. This equates to some 1 gramme of rare earth for a AAA battery, 60 grammes for a household power tool and 2 kilogrammes for a hybrid electric vehicle battery. Lithium-ion rechargeable batteries contain no meaningful amounts of rare earth elements.
Reference: Honda and Rhodia