The application of lithium batteries has become the backbone of modern technology, leading to a wide array of applications, from smartphones and laptops to electric vehicles and renewable energy storage systems. There are many benifit also many biggest problem with lithium batteries.
The technology that allows numerous applications to be performed on portable devices, such as smartphones and laptops, has created umpteen applications for them. However, despite there being some widespread applications and numerous advantages, many doubts and biggest problem with lithium batteries.
How Lithium Batteries Work?
Before stirring into the most considerable problem plaguing lithium batteries, let us look a little into how they work. The most used lithium batteries are lithium-ion, or Li-ion, batteries.
- The anode is the negative electrode and is mostly made from graphite.
- The cathode is the positive electrode and is mostly made from lithium metal oxide.
- The electrolyte allows the movement of lithium ions between the anode and cathode and usually refers to a liquid or gel.
Separator is a thin material that acts like a center that separates the anode from meeting the cathode and shorting. On charging, the anode charges because lithium ions flow from the cathode to the anode, and on discharge.
The lithium ions move in reverse flow to the cathode, releasing electrical energy. Though it works well most of the time, it is, however, not void of hazards.
Safety Concerns and Thermal Runaway (Biggest Problem with lithium batteries)
The biggest problem with lithium batteries is that they can overheat, catch on fire, or even explode due to a phenomenon known as thermal runaway. Thermal runaway refers to the condition where the heat generation rate within the cell is larger than the rate at which dissipated heat is removed from the cell, leading to an uncontrollable increase in temperature.
This can result in a battery catching fire or exploding and is the source of many battery safety issues.
1. Thermal Runaway Causes
Some of the factors that can initiate the thermal runaway process include:
Internal Short Circuits
If the separator between the anode and the cathode fails, breaking or cracking, for example, these two can come into contact, thus shorting out. There is a discharge of energy in a fast manner, and it generates heat great enough to cause a thermal runaway.
Overcharging
Suppose a lithium battery is charged over its voltage limit. In that case, it can drive the system into a regime of processes called lithium plating, by which excess lithium metal is deposited on the anode. This can feed the growth of dendrite, needle-like structures that if long enough, can puncture the separator and lead to a short circuit.
Physical Damage
An internal structural collapse of a lithium battery can result from either dropping, puncturing, or some other damage type. This is, in turn, responsible for creating a short circuit or developing any other malfunction that can initiate a thermal runaway chain reaction.
Exogenous Heat Sources
Basically, any source that will leave the temperature very high, be it a fire incident, other exposure to high temperatures, or even concentrated sunlight on the battery, causes the internal temperature inside the lithium battery to reach dangerous enough levels to create a thermal runaway state.
2. Consequence of Thermal Runaway
Results from thermal runaway can be disastrous. After initialization, thermal runaway may result in the vaporization of electrolytes and a pressure rise that finally generates gas inside the battery.
If the pressure is high enough, a ruptured battery may cause an explosion. The flammable electrolyte could also ignite and start a fire, which again would be hard to extinguish.
Several risk-mitigating strategies and technologies are underway in development and implementation, including the following:
1. Advanced BMS (Battery Management Systems)
One important component is the need to establish safe functioning for lithium batteries in the form of a battery management system (BMS). The battery is monitored against its safe operating voltage, current, temperature, and state of charge, with the ability to shut off the battery should any of these either exceed or fall below safe limits.
Several of the features within the many available modern designs of BMS include:
Overcharge and Over-Discharge Protection
This prevents charging/discharging the battery past its safe voltage, subsequently reducing thermal runaway risks. Continuous monitoring of the battery’s working temperature allows the feature to recognize overeating in time to prevent thermal runaway.
Cell Balancing
BMS also maintains that in any kind of battery pack, the charging and discharging rates are all close. This will not allow the development of a weak point in any given cell, which might be the genesis of a thermal runaway event.
2. Enhanced Separator Technology
A separator forms an essential ingredient that prevents internal short circuits. The development of separator technology is focused on thermally stable and mechanically strong separators to minimize the possibility of failure.
High-Temperature Stability
The newly developed separator materials do not melt or deform at high temperatures, thus eliminating the risk of thermal runaway. Improved mechanical strength separators exhibit improved mechanical strength with added reinforcement against things like punctures and other forms of physical abuse, thereby reducing the propensity to fail and cause short circuits.
3. Safer Electrolytes
A flammable liquid is usually used as the electrolyte in a lithium battery. When ignited, it forms a high risk after the occurrence of thermal runaway.
Solid-State Electrolytes
The entirety of a solid-state battery replaces the liquid electrolyte with a solid material so that it becomes incapable of catching fire and contributing to thermal runaway. While still in development, solid-state batteries hold much promise for improving lithium battery safety.
Non-Combustible Liquid Electrolytes
There exist new formulations for liquid electrolytes currently under study, hence making them less explosive than the traditional kinds and blurring the risk of fire.
4. Thermal Management Systems
Proper thermal management is essential to avoid thermal runaway. This may involve passive or active cooling of the battery so that the device falls around the safe operational temperature range.
Passive Cooling
Heat-proof materials with high thermal conductivity can be designed with the battery, such as aluminum or graphite, to permit effective dissipation of heat.
Active Cooling
Some of these battery systems use this feature through liquid cooling or forced air cooling. It actively helps draw heat away from the battery, keeping it from reaching temperatures that can become hazardous.
5. Safety Standards and Protocols
Risks associated with lithium batteries have meant that there have been a variety of standards and protocols that outline design, the manufacturing process, and even the application of the batteries.
Conclusion
Safety issues are always the biggest problem with lithium batteries. But the thermal runaway issue that would make them a cause for explosion and ignition is no small one; neither is it an insurmountable problem.
Most of the risks involved with lithium batteries are now being overcome due to continued developments in battery management systems, separator technologies, safer electrolytes, and thermal management systems.
Even with enhanced safety and reliability, research in this area, if pursued, could yield new technologies and alternatives. Understanding the risks and taking the proper precautions will, therefore, be critical for any user of lithium batteries in their device or application.
