What are the reasons for electric car battery aging?

　　Author ：Iflowpower – Portable Power Station Supplier

I often see the lovely users asked a message in the commentary area: "Is electric car battery aging quickly" It can only be used for a long time. ". Think about it, in the three major core components (batteries, motors, electrical controls) on electric vehicles, the cost of photovoltaic cells accounts for 30% to 50% of the whole vehicle.

Bad battery is half a car, can you not care? "The poor theoretical life is long" depends on its physical characteristics, the battery "actual life is short" depends on the user's personal usage habits. It is like to use iPhone, some people still have no different years later, and some people have to carry charging treasure to take the treasure, the same reason. Before you start, you will have a knowledge point in our science: the most common battery on electric cars is tight, two kinds of lithium phosphate, essentially of lithium ion batteries.

Due to no memory effect, the tightness of lithium-ion battery life is "full charge and discharge cycle". The full charge and discharge cycle is that the battery is completed at a 100% electricity charging, such as "completion of rechapoal, one-time from 0% to 100%", "and" Part to use part, two from 30% 80% is a complete charging cycle. When the number of cycles reaches a certain limit, the battery margin is not enough to use, this time we say the battery life cycle is over.

So, what habits can extend the life cycle of the battery? Habits 1: Shallow and light It belongs to excessive discharge; when the battery is charged between 20% to 90%, it is not charged to 100%, it belongs to shallow charge. There are many people to be strange here: Do you have a repeated charge? Isn't it a lot of charging?. Let's take a look at the premise above, the battery life is based on "full charge and discharge cycle", not the number of single charging.

That . Why is it shallow and shallow? From the molecular level, excessive discharge will cause the negative pressure ink to over-release lithium ions, so that the structure is collapsed; overcharge will put excessive lithium ion hard to move In the negative graphite structure, some lithium ions are deposited, and they can no longer be released. At the same time, excessive discharge will cause copper electrical plating of the negative electrode plate to the positive electrode, destroy the microstructure of the positive electrode.

However, good charging technology is also progressing, and now the excess festival can be handed over to the power management system (BatteryManagementSystem), which will strictly control the power of the battery, thus ensuring that the battery has been working in a safe state. However, such battery management system is limited and cannot cancel the impact of over-charge. Therefore, in the daily car, it is best not to charge the battery for light, and go home when you go home, you can press it.

Develop a good habit of shallow and shallow, so that your battery loss is slower. Habit 2: Preferred regular charging, use less fast charge to understand this, first of all, the principle of charging and discharge of the battery. The lithium-ion battery has two poles, the positive electrode is a lithium compound, and the negative extreme graphite.

Charging and discharging, actually a process of chemical energy and electrical energy mutual conversion: When charging, under electric field use, lithium ions are embedded to the negative electrode micropores, store a certain amount of energy; discharge, chemical reaction, these belts The lithium ion of charge is inserted, so that the positive electrode is in a lithium state. This process has formed a current supply. In the ideal state, the lithium ion battery can guarantee for a long period of time and multiple times as long as the chemical structure of the positive and negative electrode material does not change.

However, the principle of fast charge is to make lithium ions quickly embedded and embedded in the negative electrode, increasing the flow of lithium ions. When the current is increased, a layer of semipermeable membrane (SEI film) in the surface of the electrode negative electrode (graphite) will be broken, so that the electrode material and the electrolytic solution are reacted with each other, and the temperature increase will cause the internal side effect to destroy the battery. The chemical substance, resulting in reversibility, multiple original, make battery capacity decreased.

So saying, isn't that fails?. At this stage, the fast charge, the purpose is still an emergency. When the time is limited, when it is urgent to charge, the fast charge can solve the urgent need, but in the daily car, slow charging is a more appropriate choice.

Going home from get off work, stopping in the garage, chargeing a few hours, it is not allowed to protect the battery. Habits 3: Don't use the car in extreme temperatures, many electric car owners must be bored: Why is the winter arrived, the electric car endless pen is directly reduced? Some originally used the electric vehicle without internal combustion engine, can not use the engine waste heat. And the current two mainstream processing methods "heat pump air conditioning system" and "electric compressor air conditioning system + PTC" have a common problem - a large number of electricity.

The reason for another part is the effect of low temperature environment on electrolyte activity inside the battery. In a low temperature environment, the diffusion motion capability of the positive electrode material is deteriorated, and the passivation film of the electrode and the electrolytic solution becomes more difficult, and the transmission speed is also reduced. Even after the lithium ions reach the negative pole, the diffusion inside the material has also become inconsistent, and it may even form lithium condensation at the negative electrode.

A short time is reflected as a sharp decline in battery capacity, and it is often shortened for battery life. Under high temperature conditions, the electrolyte activity is strong, and the analytical reaction is prone to occur. The analysis product is combined with the positive material, consumes the positive electrode material.

The positive electrode material is corroded, the lattice structure is collapsed due to lack of sufficient substance support, and the lithium ion vacancy is reduced, and the positive electrode is lowered to the lithium ion, so that the battery capacity is reduced. At the same time, the by-products of the chemical reaction wanders in the electrolyte, which may be attached to the surface of the positive and negative electrode. The surface of the electrode is tipped by other substances, which hinders the smooth progress of the reaction conversion, and the internal resistance of the battery increases.

Received power. Habits 4: The guards are violently driving and running at high speeds, and the key factors that truly determine the battery theoretical life is the number of cycles. In theory, there is a limit of each battery pack, which is roughly 800 ~ 1200 times.

Unlike the mobile phone one day, the charging frequency of electric vehicles is roughly charged by one week, with this, to achieve the same cycle, some people need to be 12 years, some people have to have more battery batteries True life. A good driving habit, to a large extent, can help you pull this gap. "Military driving - faster power consumption - more frequent charge and discharge - The faster cycle is consumed, the battery life is shortened", "the simple logic chain should understand.

It should be noted that friends who are often driving must know the urgent stop, accelerate, traffic jams, but in addition to these items, there are high-speed driving.