What Takes Away Your Capacity of EV Lithium Batteries?

A parasitic draw is anything that uses energy from the vehicle in your car or truck. Some parasitic drain is perfectly normal in order to power things like interior lighting, clocks, radio settings and alarm systems. The problem occurs when your electrical system isn’t functioning properly. Issues such as faulty wiring, bad fuses or interior lights that fail to shut off will continue to drain your battery while it’s idle.

Why a few years after buying a car, the life of your lithium battery has shrunk significantly? Why the longer you drive, the more severe your battery attenuation? From the moment you are about to buy an electric car. These problems seemed to be in your heart. And these problems will become an inseparable knot in everyone’s heart. Battery life has always been the most concerned thing for electric vehicle owners. And it’s one of the topics that reflects more. Today, we will lead everyone to find answers and understand the truth about the attenuation of electric vehicle batteries.

Why do Capacity of EV Lithium Batteries Decay?

At present, there are two more common types of power batteries for electric vehicles on the market. The first is lithium iron phosphate batteries, and the second is ternary lithium batteries. More ternary lithium batteries are used. It is characterized by relatively high energy density, smaller volume under the same conditions, and better low temperature performance.

But no matter what kind of lithium battery it is, in fact, their working principle is similar. The charging and discharging of lithium batteries is done by the movement of lithium atoms between the positive and negative electrodes. Every time the lithium atom completes a charge-discharge cycle, that is, after it is fully charged and discharged, the electrode structure will change, and this change will cause the performance of the battery to decrease over time. This is what we call battery attenuation. In fact, with the increase of the mileage and service life of electric vehicles, there will be a certain attenuation in the driving range, which is a normal phenomenon. However, the attenuation is not uncontrollable, there are ways to delay the attenuation!

How to Identify the Attenuation of the Battery?

With the explosive development of the new energy industry, there are a variety of electric vehicles produced by different car companies on the market. Therefore, the degree to which each car owner encounters battery attenuation may also be different. At present, the attenuation of electric vehicle batteries is mainly divided into two types: one is normal attenuation and the other is abnormal attenuation. The normal attenuation is in accordance with national regulations during the warranty period. If the battery attenuation exceeds 20%, the manufacturer can be asked to replace it free of charge.

So, what kind of phenomenon will occur in abnormal attenuation?

1. The charging power drops or the range drops significantly under the same power

The first is that the charging power drops or the range is significantly shortened under the same power. For example, the normal mileage in the brand new state is 400 kilometers, but now there is only 200 kilometers left. It used to charge 25 kilowatt-hours of electricity, but now it can only charge 15 kilowatt-hours of electricity.

1. Increase in charging time or increase in power consumption

In addition, the charging time increases. Due to the attenuation of the battery, the performance of the battery decreases, and the charging time will become longer. For example, it only took us half an hour to charge from 20% to 80% before, but now it takes an hour, and the battery drops very quickly and is not durable, etc. , These are abnormal attenuation phenomena.

1. Lithium battery can not charge to 100%

Another is that it has not been charged to 100% of the power, but the vehicle charging system recognizes that it has been charged to 100% of the power, and displays 100% on the battery level, and then stops charging. The consequence is that although it shows that it is 100% power, in fact, these power levels are particularly non-running and power-down is very fast.

How to Delay Battery Aattenuation?

In fact, not only the power batteries of electric vehicles, but also our mobile phones and computers will experience battery attenuation. The battery is just like the human body. You have to give it a very healthy working environment. This includes temperature, which should not be too high or too low; do not use the battery violently and minimize high-power charging and discharging; and do not use the battery to recharge at a very low level. Try to keep the battery in the range of 20%-90%. Just use it.

Why are Lithium Batteries Afraid of Cold?

1.  In a low temperature environment, the activity of the cathode material decreases, the viscosity of the electrolyte increases, and the migration of lithium ions in the electrolyte slows down. Therefore, the charge migration impedance increases and the electrical conductivity deteriorates.
2.  The low temperature reduces the ability of the negative electrode material to embed lithium, and the lithium ions have been reduced to lithium metal before they are even embedded in the negative electrode. This reaction will consume lithium ions and greatly reduce the battery capacity. If the lithium battery is in a low temperature environment for a short time, this damage is only temporary and will not cause damage to the battery capacity. When the temperature rises, the performance will recover.

If you work and discharge in a low temperature environment for a long time, part of the lithium metal persists on the surface of                  the  negative electrode and cannot be embedded again, it will precipitate and precipitate, forming lithium dendrites. If the lithium              dendrites pierce the diaphragm and cause a short circuit inside the battery, it will damage the battery and even bring safety risks.

Tips:

1.  When the temperature is low, the vehicle needs to be charged in time after use, and the battery is in a relatively warm state at this time. The battery has good activity and high charging efficiency.
2.  Try to park the vehicle in a warm garage.
3.  It should be avoided to leave the vehicle outdoors in the cold for a long time

Why do Lithium Batteries Prefer Slow Charging?

The nature of the embedded reaction determines that lithium batteries are not suitable for high magnification charging. Under high-magnification charging conditions, the current density is too large, and the lattice of the cathode material is easily damaged. The graphite sheet layer of the cathode may also be damaged, and the deposition of lithium ions will be more obvious. The risk of lithium dendrites forming on the surface increases.

When the battery is charged and discharged for the first time, a SEI film will form on the negative electrode. SEI membrane is a deposit formed by electrolyte and lithium ions. The formation of the SEI film consumes lithium ions. The rapid de-embedding of lithium ions during fast charging will cause changes in the spacing of the graphite structural layers, resulting in stress deformation. When the SEI is unstable, the membrane will be destroyed and a new SEI membrane will be formed again, resulting in a further reduction of recyclable lithium, while increasing the internal resistance, causing the battery capacity to decay.

Tips:

1. 1. Because of the protection of a powerful battery management system, the damage to the battery from occasional DC fast charging is negligible.
2. 2. If conditions permit, it is recommended to choose AC slow charging as much as possible
3. 3. Avoid stepping on acceleration while driving, and avoid instantaneous high-current discharge. This is also a kind of protection for the battery.

Why are Lithium Batteries Afraid of Overcharge and Over Discharge?

Within the appropriate range, when lithium ions prolapse and embed from the positive electrode, it will cause a phase transition in the crystal structure of the cathode material, which is reversible. When overcharging occurs, excess lithium ions prolapse from the positive electrode, which will cause irreversible phase transition or even collapse of the positive electrode structure, and the battery capacity will be attenuated. Excessive lithium ions embedded in the negative electrode will also cause the deposition of lithium metal on the surface of the negative electrode and even generate lithium dendrites. When overcharged, the electrolyte will also oxidize to produce in-solubles and gases. These in-solubles will clog the micro-pores of the electrode and hinder the migration of lithium ions, causing capacity loss.

Similarly, when the battery is over-discharged, the structure of the negative electrode carbon sheet may collapse, limiting the free de-embedding of ions. Further over-discharge will cause the negative electrode copper foil to oxidize, the internal yang of the battery will increase, the capacity will decrease, and the attenuation of life will not be restored.

Tips:

1. 1. Pay attention to the remaining power information to avoid recharging when the power is exhausted
2. 2. If stored for a long time, it is recommended to fully charge the battery every three months, and then discharge it to 40%~60% for storage to avoid overloading the vehicle battery.

Why does the Vehicle Lose Power When it Can’t Be Parked for a Long Time?

When the battery is not in use, the capacitance will naturally be lost. This phenomenon is called self-discharge. There are two types of capacity loss caused by the self-discharge of lithium batteries: one is reversible capacity loss; the other is irreversible capacity loss. Reversible capacity loss can be restored during charging. The oxidation rate of the electrolyte solvent has a direct impact on the self-discharge rate. The positive and negative electrode active materials may react with the solute during the charging process, causing lithium ion migration, unbalancing the battery capacity, and irreversible attenuation.

When self-discharging for a long time or frequently, ions will form a certain deposit, increasing the degree of capacity imbalance between the poles, and further leading to the loss of battery capacity.

Tips:

1. 1. When the vehicle cannot be parked for a long time, it can be started remotely regularly to keep the battery active.
2. 2. The best way is not to store it for a long time.

Why should the Lithium Battery Maintain the Right Amount of Power?

From the moment the electrolyte is injected, the chemical reaction inside the lithium battery begins. The higher the voltage, the more intense the chemical reaction, and the more unstable the electrode material structure tends to be. Therefore, long-term storage of the battery at full power will accelerate the aging of the lithium battery.

Tips:

1. 1. When the vehicle is parked for a long time, it is recommended to keep the battery power between 40% and 60%, which can effectively protect the battery and extend battery life.
2. 2. In normal use, under the premise of meeting the battery life, the power between 30% and 80% will make your car more powerful.

Conclusion

At first glance, does lithium battery look like a particularly difficult baby to raise?You can’t be hot, you can’t be frozen, you can’t eat too much, you can’t eat too little, and you can’t eat too fast. . . . . . If you are not careful, your life span will be halved. In fact, there is no need to worry too much, the cathode material of lithium batteries itself has a very stable crystal structure. This lays the foundation for the longevity of lithium batteries. Coupled with excellent battery management algorithms and strict thermal management design, it can ensure that users can use lithium batteries safely for a long time. As long as you use the car to maintain the car correctly under the guidance of the vehicle user manual, I believe your battery will be able to prolong your life.

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