ENVIRONMENTAL IMPACT OF LITHIUM ION BATTERIES
FLEELY DISCUSSES SAFETY, PROS AND CONS AND ENVIRONMENTAL IMPACT OF LITHIUM ION BATTERIES.
FLEELY OBSERVED FOLLOWING SAFETY CONCERNS OF LITHIUM ION BATTERY FAILURES:
Lithium-ion battery failures can occur due to imperfections in the construction of the cell or through abuse. Abuse of cells can be caused by impacts such as dropping or collisions in transit, piercing from tooling, shorting, over charging and being exposed to higher or lower temperatures than those that the battery is designed for. Once a battery has been damaged it may take some time to develop symptoms such as swelling or heating.
Lithium-ion batteries can react in a variety of different ways depending on the type of fault, the area that is damaged, state of charge and chemistry of the affected battery. It has been difficult to consistently predict the same failure behavior of a cell, even in laboratory conditions.
- Damaged cells may vent / smoke without ignition.
- Fires may occur when the electrolyte ignites.
- A jet of flame and burning material being ejected from a single point can create a flare.
- The battery may burn or create a fireball, depending on the failure mode.
- The battery may also explode.
Lithium-ion cells can transition between reactions. Venting cells can catch fire, then explode, they may also vent then explode without catching fire.
SNOWBALL EFFECT: Once a battery cell has failed the heat generated can cause other cells in close proximity (stored together or together in modules and packs) to fail, resulting in a chain reaction.
CONTROL MEASURES TO LITHIUM ION BATTERY HAZARDS:
- Storage and Movement:Correct storage and protection of batteries is vital to reduce the risk of damage. If forklift trucks are used for transportation, controls must be in place to reduce the risk of piercing or damaging cells. If stored at height, protection should be given to prevent batteries from falling. Batteries should be segregated as much as possible to prevent a failure propagating through storage or work areas.
- Remove the Risk of Damaging Batteries When Possible:For maintenance tasks, alignment operations and training “dummy” batteries should be used where possible. Dummy batteries are constructed to resemble components, however they are inert, meaning that if they are damaged that they will not react in the same way a ‘live’ component with electrolyte would.
- Detection, Monitoring and Reacting to Failing Batteries:Monitoring systems should be used where a risk assessment has identified the need to monitor the temperature of batteries as failing devices tend to increase in heat before more severe reactions occur. Evacuation routes and other plans should be prepared and practiced well in advance to ensure employee safety in case of an emergency.
Whenever working around a potentially damaged battery, appropriate protective equipment should be available.In the event a battery system does vent hazardous fumes, a system of ventilating the area should be considered.
- Charging Systems:Only approved charging systems should be used to prevent overcharging. Many of the incidents involving vape devices are caused by poor quality chargers. Any charging device used must be evaluated to ensure it is fit for purpose.
- Protection from Shorts Circuits and Electric Shock:Protection should be provided to prevent short circuits such as guarding connections, insulated tools and removal of all non-essential conductive materials such as coins and jewellery.Isolation procedures should be provided to disconnect the battery system in line with procedures such as lock out tag out (LOTO) however, maintaining or constructing battery modules and packs can pose risks of electric shock that cannot be eliminated.
LITHIUM ION BATTERIES SAFETY STANDARDS AND TESTS:
To reduce the thermal runaway risk in commercially available products, LIBs for vehicles should be certified in accordance with relevant safety testing standards before mass production or sale. Safety test standards are designed to ensure that certified LIBs have sufficiently low risks of safety accidents in specified kinds of thermal runaway induction and expansion situations.
- Chinese standard GB/T 31,485
- Society of Automotive Engineers (SAE) standard 2464
- International Electrotechnical Commission (IEC) standard IEC62133 Edition 2.0
- United Nations (UN) standard UN38.3
- Japanese Industrial Standard (JIS) C8714
- Underwriters Laboratories (UL) standard UL2580 Edition 2.0
- International Standardization Organization (ISO) standard ISO 16750–2
The test standards are formulated to reduce the probability of thermal runaway accidents in actual use. Thus, they are intended to assess responses of batteries in real potential situations, with continuous updates and upgrades in accordance with the ongoing development of LIB technology, which reflects concerns about the causes and hazards of accidents that have occurred.
LIB safety assessment involves a myriad of tests that a battery must pass to certify that it will not be hazardous under specified abuse conditions.
- Overcharge tests: According to the IEC standard test, the cell is first discharged to 3.0 V at 0.2C rate, and then is charged under 10 V and an arbitrarily set current I within the time is equal to 2.5×C5.I. If the battery does not combust or explode during or after the test it is considered safe, its materials are regarded as having adequate properties, and the structural design is deemed satisfactory.
- Heating tests: Heating is used to analyze LIBs’ thermal stability and heat distribution to ensure they have sufficiently efficient heat management and capability to forecast potential hazards. The results are then used to assess how thermal abuse consequences can be alleviated.
- Short circuit tests:
Internal Short Circuit Tests: A designed external short-circuit test is aimed to evaluate the LIB safety performance. According to the GB31485-2015 procedure, the battery is kept at 25 ± 2 ℃ in a fully charged state for 30 minutes, then the cathode and anode terminals are connected with a wire, and the external resistance is kept at 5 mΩ. During this test, the temperature and voltage are monitored simultaneously, throughout the entire test. The test is considered successful if the cell does not explode or combust
External Short Circuit Tests: High current passes through a short-circuited site, generating a large quantity of heat, which might cause thermal runaway. Thus, tests have been developed to assess battery performance under internal short-circuit conditions, and the International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE), Underwriters Laboratories (UL), and other organizations have published reports on specific short-circuit simulation methods.
- Nail penetration tests: These tests are designed to simulate internal battery short circuits that may occur when a battery’s internal membrane is penetrated by impurities. According to GB/T 31485, a fully-charged battery should be penetrated with a high temperature-resistant steel spike of φ 5 ~ 8 mm in a direction perpendicular to the polar plate at a speed of 25 ± 5 mm/s. The penetration position should also be close to the geometric center of the penetrated surface, with the steel spike retained inside the battery. The test is considered successful if the cell does not explode or combust.
- Crush tests: During a crush test, a battery is mechanically compressed. According to GB/T 31485, the cells are first charged at 1C rate to 4.2 V, then the battery is placed between two planes in a semi-cylinder with a 75 mm radius, and subjected to crushing at 5 mm/s, with a load applied in the direction perpendicular to the battery’s polar plate. The crushing is ceased when the voltage reaches 0 V, the deformation reaches 30%, or the crushing load reaches 200 kN. The test has a positive outcome if no fire or explosion is observed.
ADVANTAGES OF USING A LITHIUM ION BATTERY:
- High energy density: The high energy density is one of the chief advantages of lithium ion battery technology. With electronic equipment such as mobile phones needing to operate longer between charges while still consuming more power, there is always a need for batteries with a much higher energy density. In addition to this, there are many power applications from power tools to electric vehicles. The much higher power density offered by lithium ion batteries is a distinct advantage. Electric vehicles also need a battery technology that has a high energy density.
- Self-discharge: One issue with many rechargeable batteries is the self discharge rate. Lithium ion cells are that their rate of self-discharge is much lower than that of other rechargeable cells such as Ni-Cad and NiMH forms. It is typically around 5% in the first 4 hours after being charged but then falls to a figure of around 1 or 2% per month.
- Low maintenance: One major lithium ion battery advantage is that they do not require any maintenance to ensure their performance.
- Cell voltage: The voltage produced by each lithium ion cell is about 3.6 volts. This has many advantages. Being higher than that of the standard nickel cadmium, nickel metal hydride and even standard alkaline cells at around 1.5 volts and lead acid at around 2 volts per cell, the voltage of each lithium ion cell is higher, requiring less cells in many battery applications. For smartphones a single cell is all that is needed and this simplifies the power management.
- Load characteristics: The load characteristics of a lithium ion cell or battery are reasonably good. They provide a reasonably constant 3.6 volts per cell before falling off as the last charge is used.
- No requirement for priming: Some rechargeable cells need to be primed when they receive their first charge. One advantage of lithium ion batteries is that there is no requirement for this they are supplied operational and ready to go.
- Variety of types available: There are several types of lithium ion cell available.This advantage of lithium ion batteries can mean that the right technology can be used for the particular application needed. Some forms of lithium ion batteries provide a high current density and are ideal for consumer mobile equipment and others which could provide much heavier currents are ideal for power storage and electric vehicles.
DISADVANTAGES OF USING A LITHIUM ION BATTERY:
- Protection required: Lithium ion cells and batteries are not as robust as some other rechargeable technologies. They require protection from being over charged and discharged too far. In addition to this, they need to have the current maintained within safe limits. Accordingly one lithium ion battery disadvantage is that they require protection circuitry incorporated to ensure they are kept within their safe operating limits.
- Ageing: One of the major lithium ion battery disadvantages for consumer electronics is that lithium ion batteries suffer from ageing. Not only is this time or calendar dependent, but it is also dependent upon the number of charge discharge cycles that the battery has undergone. Often batteries will only be able to withstand 500 - 1000 charge discharge cycles before their capacity falls.
- Transportation: This li-ion battery disadvantage has come to the fore in recent years. Many airlines limit the number of lithium ion batteries they take, and this means their transportation is limited to ships.
- Air travelling cautions: lithium ion batteries often need to be in carry-on luggage, although with the security position, this may change from time to time. But the number of batteries may be limited. Any lithium ion batteries carried separately must be protected against short circuits by protective covers, etc. It is particularly important where some of the large lithium ion batteries like those used in large power banks.
- Cost: A major lithium ion battery disadvantage is their cost. Typically they are around 40% more costly to manufacture than Nickel cadmium cells. This is a major factor when considering their use in mass produced consumer items where any additional costs are a major issue.
- Developing technology: Although lithium ion batteries have been available for many years, it can still be considered an immature technology by some as it is very much a developing area. This can be a disadvantage in terms of the fact that the technology does not remain constant. However as new lithium ion technologies are being developed all the time, it can also be an advantage as better solutions are coming available.
Lithium-ion batteries contain less toxic metals than other batteries that could contain toxic metals such lead or cadmium,they are therefore generally considered to be non-hazardous waste. Most of the elements within lithium-ion batteries such as iron, copper, nickel and cobalt  are considered safe for landfills and incinerators. While safe for the landfills, the physical mining of lithium and the production of lithium-ion are both incredibly labor intensive with a majority of it not being recycled, causing the impacts on the environment to be costly. On top of this, as lithium-ion battery production increases, this causes a demand strain on the precious metals needed to produce lithium-ion and may cause environmental concerns from the waste generated in this. The extraction process of lithium is very resource demanding and specifically uses a lot of water in the extraction process. With the world's leading country in production of lithium being Chile , the lithium mines are in rural areas with an extremely diverse ecosystem