Electric Vehicle Perspectives from a Security Perspective
Today there is an increased interest in reducing pollution. In addition to renewable power sources, as a replacement for traditional energy, various options for replacing internal combustion engines in cars as a source of local pollution are considered.
Here the topic of electric vehicles has already been discussed:
Modern electric cars - the story from the beginnings to the horizons
Battery use after end of life
The production of batteries by Tesla
The near future of rechargeable batteries
')
But is this a good idea from a security point of view?
Today, in the trucking industry, one of the three battery technologies is most commonly used: lead-acid batteries, lithium-ion batteries, and supercapacitors.
It is obvious that at the moment, by the energy / mass ratio, it is lithium-ion batteries.
The theoretical voltage limit of a modern unit in the 18650 format is 4.2 V, but no battery allows it to be used. The problem is that when lowering below the safe level, the so-called Lithium plating occurs - the formation of conductive plots of lithium, which leads to an internal short circuit and, as a result, to thermal battery acceleration (thermal runaway). A similar situation may also occur when the temperature drops sharply. If the voltage is exceeded, the temperature instability of the cell occurs, which also leads to its destruction.
Thus, there is a need to limit the stresses from above and below, also because there is some variation in characteristics during production.
To date, batteries with voltages of 2.1 V cells with LTO and LiFePO 4 electrodes are considered the safest in this respect, but for security one has to pay a decrease in voltage, and therefore available energy, twice.
The second main problem is the strength of the batteries in collisions, because the accident has always been, is and will be. The problem of all such batteries is that when they are destroyed, a fire occurs that can be extinguished only with the use of special equipment.
As a rule, when punching a lithium-ion battery with a 18650 form factor to 80% of cases, spontaneous combustion occurs. This is a Tesla car problem - over 6,000 of these batteries are used to power it.
The third problem, which has no solution at the moment, is the quality of the production of the battery. Problems with it can arise regardless of operation, simply by hitting foreign bodies in the battery itself.
The most striking examples that showed the problems of lithium-ion batteries are problems with the Boeing 787 and Dell. In the second case, they were simply replaced by similar ones.
The first is a more vivid example. The Boeing Company pioneered the use of lithium-ion batteries in aircraft. The battery was used not standard, larger. Due to the thermal acceleration, an explosion occurred, all the planes lost access to flying in January 2013. After the statement about the solution of the problem, the planes were again allowed to fly in April 2013. In January 2014, a battery ignited. In general, the "solution" of the Boeing was to install the battery in the fortified compartment, so the problem with the battery, the rest of the plane does not touch. The problem has not been resolved since it is physically impossible at this stage in the development of technology.
To date, there have been three Tesla car fires caused by problems in the production of batteries.
The reliability of batteries today is insufficient for mass use of batteries. In the near future, they will remain an expensive alternative, but over time, cheaper production will increase their number. And according to the pessimistic scenario, the question of the safety of the use of this car will lie on the shoulders of the owner.
In general, the safety of batteries is a very important factor, which should not be forgotten by those who use them in laptops and mobile phones. It is very likely that without the development of the automotive industry and their introduction into transport these issues would not have been so acute.
1. Course "Battery Storage Systems", RWTH Aachen, Prof. Dr. rer. nat. Dirk uwe sauer
2. About quenching lithium
3. Problems with Boeing 787 batteries
4. Battery recall by Dell
Here the topic of electric vehicles has already been discussed:
Modern electric cars - the story from the beginnings to the horizons
Battery use after end of life
The production of batteries by Tesla
The near future of rechargeable batteries
')
But is this a good idea from a security point of view?
Existing problems
Today, in the trucking industry, one of the three battery technologies is most commonly used: lead-acid batteries, lithium-ion batteries, and supercapacitors.
It is obvious that at the moment, by the energy / mass ratio, it is lithium-ion batteries.
Stability
The theoretical voltage limit of a modern unit in the 18650 format is 4.2 V, but no battery allows it to be used. The problem is that when lowering below the safe level, the so-called Lithium plating occurs - the formation of conductive plots of lithium, which leads to an internal short circuit and, as a result, to thermal battery acceleration (thermal runaway). A similar situation may also occur when the temperature drops sharply. If the voltage is exceeded, the temperature instability of the cell occurs, which also leads to its destruction.
Thus, there is a need to limit the stresses from above and below, also because there is some variation in characteristics during production.
To date, batteries with voltages of 2.1 V cells with LTO and LiFePO 4 electrodes are considered the safest in this respect, but for security one has to pay a decrease in voltage, and therefore available energy, twice.
Impact resistance
The second main problem is the strength of the batteries in collisions, because the accident has always been, is and will be. The problem of all such batteries is that when they are destroyed, a fire occurs that can be extinguished only with the use of special equipment.
As a rule, when punching a lithium-ion battery with a 18650 form factor to 80% of cases, spontaneous combustion occurs. This is a Tesla car problem - over 6,000 of these batteries are used to power it.
Production
The third problem, which has no solution at the moment, is the quality of the production of the battery. Problems with it can arise regardless of operation, simply by hitting foreign bodies in the battery itself.
The most striking examples that showed the problems of lithium-ion batteries are problems with the Boeing 787 and Dell. In the second case, they were simply replaced by similar ones.
The first is a more vivid example. The Boeing Company pioneered the use of lithium-ion batteries in aircraft. The battery was used not standard, larger. Due to the thermal acceleration, an explosion occurred, all the planes lost access to flying in January 2013. After the statement about the solution of the problem, the planes were again allowed to fly in April 2013. In January 2014, a battery ignited. In general, the "solution" of the Boeing was to install the battery in the fortified compartment, so the problem with the battery, the rest of the plane does not touch. The problem has not been resolved since it is physically impossible at this stage in the development of technology.
To date, there have been three Tesla car fires caused by problems in the production of batteries.
findings
The reliability of batteries today is insufficient for mass use of batteries. In the near future, they will remain an expensive alternative, but over time, cheaper production will increase their number. And according to the pessimistic scenario, the question of the safety of the use of this car will lie on the shoulders of the owner.
In general, the safety of batteries is a very important factor, which should not be forgotten by those who use them in laptops and mobile phones. It is very likely that without the development of the automotive industry and their introduction into transport these issues would not have been so acute.
Sources
1. Course "Battery Storage Systems", RWTH Aachen, Prof. Dr. rer. nat. Dirk uwe sauer
2. About quenching lithium
3. Problems with Boeing 787 batteries
4. Battery recall by Dell
Source: https://habr.com/ru/post/223843/
All Articles