A Study On The Explosion of Lithium-Ion Battery Packs In Electric Vehicles

The majority of the electric vehicles all across the globe use Lithium-ion battery packs to power their motor and other onboard electronic components. These lithium-ion battery packs are lightweight and possess a high power density. A couple of years ago, two Tesla cars caught fire due to a lithium-ion battery failure. The faulty lithium-ion battery is susceptible to catching fire and has caused many leading automobile manufacturers to recall back their electric vehicle models. When an EV catches fire due to battery failure, it’s not an easy task to extinguish the fire. The Automotive Stakeholders and researchers have been working towards a feasible solution that can replace the conventional lithium-ion batteries in Electric Vehicles. Over the last 30 days, we have been listening to incidents of E2Ws catching fire in India. Some of these incidents have killed people while others had no casualties. In this blog, I will be explaining the causes behind the explosion of lithium-ion battery packs with emphasis on Electric Two Wheelers. Solid-State Batteries are touted to be a safer alternative than lithium-ion batteries. I will also be highlighting the advantages and disadvantages of Solid-State Batteries.

The OLA S1 Pro Caught Fire In Pune On 29th March 2022

Instances Of Electric Two-Wheelers(E2Ws) Catching Fire In India

A father and his daughter died after their e-bike went on flames due to an electrical short circuit in Chinna Allahpuram in Vellore on 26th March 2022

Recent Cases Of Electric Two-Wheelers(E2Ws) Catching Fire In India

Over the last 30 days, there are many instances of E2Ws catching fire in India. I will be analyzing three incidents of E2Ws catching fire in India. The incidents are as follows:

1. The Death Of A Family Of Two After The E2W Caught Fire In Vellore On 26th March 2022: Father and daughter died due to suffocation after their new electric bike caught fire on 26th March 2022. The electric bike caught fire because of excessive charging of the battery pack throughout the night using an old socket with a less voltage capacity to charge an electric bike.
2. An Electric Scooter Caught Fire In Manapparai, Trichy On 28th March 2022: A 27-year-old man from Padukkakulam parked in front of his friend Balu’s shop on 27th March 2022 in Manapparai, Trichy. The next day morning, the E2W caught fire and the neighbours extinguished the fire by pouring water.
3. An OLA S1 Pro Caught Fire In Pune On 29th March 2022:An OLA S1 Pro caught fire in Pune, Maharastra on 29th March 2022. The E2W caught fire while being parked near the footpath in the afternoon. The reason has not yet been identified. OLA has announced a probe to find the reason behind the catastrophe.

These are some of the few cases of E2Ws catching fire in India and EVs catching fire in India is not a new thing. From these cases, we can understand the causes of these catastrophes. They are as follows:

1. Excessive Charging of The EV Battery Pack
2. High Temperature Of The Surroundings
3. Not Using The Prescribed Voltage And Charging Plug For The Charging The EV

Who Are Responsible For These Catastrophes?

There are three stakeholders or factors responsible for the explosion of the E2Ws. They are as follows:

1. The User: The majority of the users do not follow the specifications and rules for charging the EVs/E2Ws. They tend to Over-Charge or charge it for a prolonged period. This would deteriorate the performance of the battery pack and wreak havoc on the chemistry of the battery. Ultimately leading to the explosion of the battery pack.
2. The EV Manufacturers: The EV manufacturer would always want to close the delivery order of the Electric Vehicle as soon as possible. Sometimes these EV Manufacturers might bypass the testing protocols of the EV-Battery packs to meet the delivery deadline due to the increasing customer demands. There are high chances that these EVs might have faulty battery packs which can explode.
3. The Drawbacks Of The Lithium-Ion Battery Pack: The Lithium-ion battery pack has a liquid electrolyte. This liquid electrolyte is highly explosive in nature. These battery packs are susceptible to thermal runaway. The term “Thermal Runaway” will be explained in the next section. Thermal Runaway would finally lead to the explosion of the lithium-ion battery pack.

What is Thermal Runaway In A Lithium-Ion Battery Pack?

A lithium-ion battery uses a heavy liquid electrolyte and it is quite explosive in nature. Thermal runaway is a major issue faced by lithium-ion batteries. A chain reaction can be initiated by thermal runaway in a lithium-ion battery. Thermal runaway occurs when the temperature rises at a very rapid pace (ie in a few milliseconds) and the energy stored in the battery gets released. This phenomenon can create temperatures as high as 400 degrees Celsius and the battery becomes gaseous sparking a fire that cannot be extinguished by any conventional means. The risk of thermal runaway in the lithium-ion battery begins at 60 degrees Celsius and can become very dangerous at 100 degrees Celsius. The liquid electrolytes inside lithium-ion batteries can corrode the internal battery components and in turn, reduce the battery capacity and overall performance.

Thermal Runaway In A Li-Ion Battery

The causes of Thermal Runaway in a lithium-ion battery are as follows:

1. Internal short circuit due to an accident or mechanical damage.
2. External short circuit due to the deformation of the battery cell.
3. Overcharging the battery beyond the specified maximum voltage values.
4. Excessive currents are generated due to the discharging or charging of the battery (especially under rapid charging conditions).

The five stages of Thermal Runaway are:

1. Heating Starts
2. Protective Layer Breaks Down
3. Electrolyte breaks down into flammable gases
4. Separator melts leading to a short circuit
5. The cathode breaks down generating oxygen

What are Solid-State Batteries? How Are They Different From The Conventional Lithium-Ion Batteries?

Solid-State Batteries (SSB) are those batteries that use a solid electrolyte instead of a heavy liquid electrolyte that is being used in a lithium-ion battery. Solid-State Batteries are touted to be the future of EV Technology.

The Li-Ion Battery and Solid-State Battery

The solid electrolyte comprises ceramics, glass, or other materials. The solid electrolyte is not explosive in nature while the heavy liquid electrolyte is quite explosive in nature. The overall structure of an SBS is very much similar to that of a lithium-ion battery. The SBS is quite smaller and lighter than that of a lithium-ion battery because of the absence of the heavy liquid electrolyte. The absence of a heavy liquid electrolyte would offer more energy density, a higher travel range, and a faster rate of recharging.

Advantages and Disadvantages Of Solid-State Batteries

Solid-state batteries are predominantly used in small-scale devices like pacemakers, wearables and RFID. The large-scale automobile usage of solid-state batteries is novel. Replacing the conventional lithium-ion battery with a solid-state battery can improve the performance of an electric vehicle considerably.

Advantages of Solid-State Battery

There are seven advantages of using a Solid State Battery in an EV instead of a Li-ion battery. The advantages of the Solid-State battery are as follows:

1. Solid-state batteries are capable of delivering 2.5 times more energy density as compared to lithium-ion batteries.
2. Solid-state batteries are comparatively more durable and safe. A solid-state battery does not contain any volatile element.
3. The solid electrolyte used in solid-state batteries is non-flammable, hence they are less prone to catch fire. The greater electrochemical stability of solid-state batteries makes them more reliable.
4. Solid-state batteries are compact in nature. Solid-state batteries are comparatively lighter in weight.
5. The recharge rate of solid-state batteries is 4–6 times more than regular batteries.
6. Solid-state batteries can reach an 80-per cent charge within 15 minutes and incur less strain after multiple charging cycles. On the other hand, a lithium-ion battery will begin to degrade and lose power capacity after 1,000 cycles.
7. By using a solid-state battery instead of a lithium-ion battery, there’s no need for any of the monitoring, control, and cooling systems to be incorporated into the EV.

Disadvantages of Solid-State Battery

The mass production and manufacturing of solid-state batteries is an uphill task. Researchers are still working on finding the perfect material with the ideal conductivity for the Solid-State Battery. The conventional Li-Ion Battery is cheaper than the Solid-State Battery.

Conclusion

On a very personal note, I was deeply saddened by the death of the father and daughter after their e-bike went into flames due to an electrical short circuit and many other EV owners who helplessly watched their EVs burn. As a concluding remark, I would like to say

The Lithium-Ion batteries in the EVs must be replaced by solid-state batteries to make sure that these life-threatening catastrophes do not occur in the near future. These incidents might incite fear in those owning EVs and aspiring to own EVs in the near future. I strongly believe that solid-state batteries are the future.I understand that the mass production and manufacturing of solid-state batteries is an uphill task. If EV manufacturers all across the globe begin to use Sold-State Batteries in their EVs by investing into the R&D of Solid-State Batteries, then the mass production and manufacturing of Solid-State Batterieswould become easier and cheaper. Noting with appreciation companies like Toyota and BMW have started to work toward replacing the conventional Lithium-ion battery packs with Solid-State Batteries.