Batteries are expensive and have a relatively short life span. As discarded batteries grow by the tonnage, entrepreneurs are enticed to start a business in recycling. With an annual world market (2015) of $33 billion, lead acid is the most common battery in use. This is followed by Li-ion at $16.6 billion, NiMH at $2 billion and NiCd at $1 billion. All other chemistries only make up $1 billion. Table 1 lists the material cost per ton to build these batteries.
Lithium-ion batteries are expensive to manufacture and this is in part due to the high material cost and complex preparation processes. The most expensive metal of most Li-ion is cobalt, a hard lustrous gray material that is also used to manufacture magnets and high-strength alloys.
Knowing that billions of Li-ion batteries are discarded every year and given the high cost of lithium cobalt oxide, salvaging precious metals should make economic sense and one wonders why so few companies recycle these batteries.
The reason becomes clear when examining the complexity and low yield of recycling. The retrieved raw material barely pays for labor, which includes collection, transport, sorting into batteries chemistries, shredding, separation of metallic and non-metallic materials, neutralizing hazardous substances, smelting, and purification of the recovered metals.
Recycling programs for lead acid are said to have started soon after Cadillac introduced the cranking motor in 1912 as a for-profit business rather than protecting the environment. Recycling can be harmful, especially with lead acid batteries. Lead can enter the body by inhaling or ingestion when touching the mouth with lead-contaminated hands. This puts workers and residents of the surrounding areas at risk of lead poisoning.
The EPA (Environmental Protection Agency) has imposed strict guidelines in recycling of lead acid batteries in the USA. The recycling plants must be sealed and the smokestacks fitted with scrubbers. To check for possible escape of lead particles, the plant perimeter must be surrounded with lead-monitoring devices. Rules are bound to be broken and batteries soon end up in Mexico and other developing countries with relaxed regulations. China, a leader in lead acid battery production, also took action to protect the environment by introducing strict guidelines that only reputable companies can meet.
Nickel-based batteries can also be recycled and the retrieved materials are iron and nickel, which are used in stainless steel production. Nickel-metal-hydride (NiMH) yields the highest return in nickel, and with ample supply recycling is said to make money. Low demand for cadmium has reduced the profitability from recycling NiCd batteries. The growth in batteries is with Li-ion but valuable materials are difficult to retrieve. This makes Li-ion less attractive for recycling and a financial breakeven may not be possible without subsidies.
The true cost to manufacture Li-ion is not so much in the raw materials, as is the case with lead acid and NiMH, but in lengthy processing and purification processes of the raw materials to reach battery grade. Retrieving lithium at only 3 percent of the cell mix may never reach break-even levels. If the purity of lithium is below 99.5 percent, then it is not suitable as raw material for batteries. Recycling brings the metal to ground zero, from which costly preparations begin anew. It is often cheaper to mine raw material than to retrieve it from recycling. Lithium from recycled batteries is commonly used for non-battery applications, such as lubricating greases that are found in WD-40 and other products, rather than batteries.
Direct recycling technologies for lithium-ion batteries my offer a solution in refining used Li-ion into high value cathode and anode materials. Direct recycling may become profitable if the technology can be developed to large-scale processing made possible with high volume EV batteries reaching end-of-life. Direct recycling is said to be cleaner than older methods that melt the material.
Although alkaline and zinc-carbon account for over 90 percent of batteries consumed in the United States, they contain few precious metals and the toxicity is low. Organizations are seeking ways to recycle these batteries as well for the basic metal content and with high volume such a venture should become viable. Table 2 lists the typical metals content of commonly recycled batteries.
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