The Hazards And Safety Aspects Of Recycling Lithium Batteries

As seen in the previous section there are numerous types of lithium batteries. In this section, we shall look at the generic hazards of primary (with liquid or solid cathode) and rechargeable batteries. There is much controversy over the reactivity of several individual chemistry types. It is the authors opinion that there are inherent hazards associated with any battery type or energy source and in most situations the hazards and size are directly related. In a similar scenario, lithium batteries in general cannot be categorized into being more or less hazardous than any other chemistry without knowing the exact type and size of the systems to be compared.

The hazards of any battery system increase with size (as mentioned above), but in contrast, depending on the type, a smaller lithium system may be much more reactive than a larger lithium system of a different type.

Hazards of Primary Batteries

In the case of the primary lithium systems, the hazards for the most part involve the safe processing and management of the elemental lithium and associated hydrogen gas. Eliminating the random very violent reactions is paramount when considering the safe processing of the batteries for recycling. Once lithium and hydrogen are controlled, the components within the battery can be exposed, separated, neutralized, reprocessed, and separated again or re-manufactured into marketable materials. Primary lithium batteries exhibit the following hazards.

When Subjected to Abusive Environments Large Primary Lithium Batteries Can React Violently. This is the venting of the largest primary liihium battery ever made (10,000 AH)

1) Because the reaction of lithium with water quickly generates hydrogen and heat, and because a lithium battery can spark if shorted, there is extreme risk for fire, flames, and violent deflagration. Violent deflagration simply means that the destructive pressure wave generated when a battery vents has a slight rise-time when plotted versus time. A pressure wave from an explosion, on the other hand, has zero rise-time. It should be noted that to the common observer, under abusive circumstances, lithium primary batteries may certainly look like explosive.

2) Soluble-cathode lithium primary batteries most times contain very toxic cathodes and flammable solvents. These types of batteries are seldom seen outside of the military in sizes larger than a button/coin cell. They are common in some heavy industrial or remote processes including oil-drilling operations. They are extremely common in many military forces throughout the world.

3) Any lithium primary battery under the right (or wrong) circumstances can vent fire and flames similar to a torch.

4) The hazards of a lithium primary system increase by magnitudes as the size of the battery increases. Large lithium primary batteries or cells of any type can be very dangerous if not handled properly.

Hazards of Secondary Batteries

Recycling lithium rechargeable battery systems does not involve elemental lithium under normal conditions. It is the authors belief that a fully charged large nickel metal-hydride battery has the potential to be much more reactive than a comparably sized lithium secondary. The metal-hydride battery worst-case hazards include the possibility of very high hydrogen concentrations within the battery case. In certain situations this could result in a violent hydrogen reaction (this violent reaction, by the way, would not be considered deflagration but instead is an actual explosion). Because there is no elemental lithium, many of the hazards of processing lithium ion systems are similar to other non-lithium battery systems. There are also new hazards and, as in the case of the primary lithium batteries, each type must be evaluated. The lithium ion rechargeable systems are much less reactive than lithium primary systems for several reasons:

1) There is no elemental lithium (under normal use scenarios), thus there is very little hydrogen generated. There is the possibility of elemental lithium being produced if the charge control circuitry has failed. This possibility cannot be overlooked in the case of a commercial recycling facility.

2) The electrolytes are less reactive than most soluble-cathode primary batteries. Sulfur dioxide, thionyl chloride and sulfuril chloride are extremely toxic and quickly fume when exposed to moisture (forming very acidic mists).

3) There is very little free electrolyte in lithium secondary systems, thus reducing the possibility of spilling acidic liquids.

The hazards of the lithium secondary systems are described below and must be considered in any recycling process.

1) The non-aqueous electrolyte is primarily composed of flammable organic solvents.

2) Large heavy batteries can consist of many cells with high cumulative voltages. This naturally increases the risks of electric shock and crushing injuries.

3) The battery electrolyte is toxic.

4) The presence of elemental lithium can sometimes occur if the charge control circuitry fails.

Hazards Considerations

Lithium batteries when new or fully charged are capable of possessing large amounts of electrical energy (as do many types of batteries). When received at a recycling facility, most of this energy should be dissipated since the majority of batteries sent for recycling should be depleted. A commercial recycling facility cannot count on this being the situation in all cases. Consumers and industry alike mix new and used batteries in many applications. They change the batteries of several systems (i.e. radios, flashlights etc.) even though only one actually needs new batteries or they replace one or two cells instead of replacing all of the cells from a system. As a result, batteries received for processing vary in depths of discharge from fully depleted to fully charged. Multi-cell batteries should always be treated as fully charged to avoid serious injury. This electrical energy can also (and will eventually) create a spark. Sparking can occur under abusive circumstances such as terminal-to-terminal shorting or internal shorting due to piercing or crushing the case. In the presence of a spark the electrolyte, packaging material and other combustible material will cause a fire. Some organic electrolytes have a low vapor pressure and will quickly evaporate into the air. The organic vapors must be managed to reduce the risk of personnel exposure as well as to prevent the formation of extremely flammable environments.

In a similar scenario, there is no sorting equipment available that can distinguish between the various chemistries of lithium batteries. Consumer collection or recycling facility efforts many times depends on manually sorting the various types of batteries. Batteries are shipped with the wrong shipping or safety documents and may even be mistaken for other types of batteries all together. The point is that a recycling facility must be prepared for the worst case scenario when it is least expected. A facility must put a high priority on screening, quality control and safety.

Worker and personnel safety should always be considered in a recycling environment. Battery safety consists of many common sense concepts as well as several that are not common sense.

1) Wear eye protection.

2) Wear safety shoes.

3) Wear long sleeves when working with neutralization chemicals or battery electrolytes.

4) Use chemical resistant gloves, apron, and face shield when working with the electrolyte or vented batteries.

5) When working with a large battery disconnect the cells.

6) Do not wear metal rings, watches, or necklaces that may come in contact with the electrical terminals of the batteries.

7) If cutting electrical wiring, cut one wire at a time to prevent shorting the battery. Use care when disconnecting cells not to short-circuit the terminals with wrenches or other metal objects. The cell cases in many situations are one side of the electrical circuit. With this in mind, never remove the protective plastic cell coating.

8) Remove all non-essential combustible material from the processing area. Remember that secondary fires cause most damage resulting from a lithium battery fire.

9) Always work in pairs or keep in contact with other workers via intercom.

10) Practice fire response in accordance with an approved response plan.

11) Practice spill response in accordance with an approved response plan.

12) Make sure fire extinguishers are accessible, clearly marked, and are the correct class for the types of fires anticipated. Graphite powder based extinguishers are the correct class for lithium primaries and can also be used for lithium ion. Copper fire extinguishers should not be used for soluble-cathode lithium primary batteries. Make sure personnel are familiar with extinguisher locations.

13) Supplied air or respirators with organic filters (for lithium secondary batteries), and acid filters (for lithium primaries), should be readily available if exposed to battery electrolytes. Respirators are not recommended for long term exposure or exposure to unknown concentrations of electrolytes.

14) Always have a copy of the battery Material Safety Data Sheet (MSDS) on file and available.

15) When disassembling a battery into cells, always refer to an electrical schematic if at all possible.

16) In most situations it is best to store the batteries in a sprinkler-controlled area. The batteries can and will start the fire but only vent reactive materials for a brief period. The chance of water actually coming in contact with elemental lithium is very remote. The water will cool most batteries in close proximity to the fire and also will prevent secondary fires as a result of the battery fire. Water should not be used on very large lithium batteries (above 1000 Ah per cell) but these batteries comprise much less than 1% of the lithium battery population and are only used in military and government applications.

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