When discussing charging speed, the battery itself is definitely one of the most unbypassable factors in terms of its ability to withstand. No matter how much the peripheral charging equipment, how much power, how strong the charging capacity, if the battery itself has shortcomings in the charging capacity that can be accepted, then the charging speed is certainly not fast. Plus if the battery capacity is relatively large, the natural charging time will be long.
If you have learned about electrochemistry in high school, you will understand the process of battery charging and discharging, the essence is that the battery internal through a series of redox reactions to achieve the directional transfer of electrons between the positive and negative electrodes. Take the mainstream lithium battery as an example, although there are various types, but the general structure includes the positive electrode material, negative electrode material, diaphragm, electrolyte, etc. The charging process is basically the lithium ion from the negative electrode, through the diaphragm and electrolyte, the process of diffusion to the positive electrode - the diffusion rate naturally becomes the charging speed of The key.
Theoretically, it is true that the charging speed can be increased by increasing the current. However, if the current is too high, the diffusion rate of lithium ions inside the battery cannot keep up with the electron diffusion rate, which will lead to the disconnection of electron-ion transport and affect the battery performance, and the charging capacity can be reduced accordingly, and the battery life will be even more miserable, and there is even a risk of fire and explosion.
So in general, in the case of not rushing, we recommend using slow charging as much as possible, in order to extend the life of the battery.
The diffusion rate of lithium ions, and temperature, the material and structure of the positive electrode is closely related.
First is the temperature, generally speaking, the higher the temperature is naturally the faster the diffusion rate, but the temperature is too high will also lead to lower battery life, charging safety and other issues. The same does not work if the temperature is too low, the temperature is too low, the deposition of lithium metal in the battery will occur, thus causing a short circuit inside the battery, especially lithium iron phosphate batteries. General 0 ℃ when the capacity of lithium iron phosphate battery is only about 60 to 70%, to -20 ℃ will be left with a poor 20 to 40%. So in the cold climate of the northern winter, electric vehicles must have to give the battery module heating function, thus power consumption is naturally faster.
Next is the material, different materials diffusion capacity gap is very large, like lithium cobaltate, lithium manganate, lithium iron phosphate, NCM, NCA, etc. are very good performance of the anode material, and the latter two are also the best performance, the application of the popularity of the two materials. This is also an important reason why today's lithium batteries are named after the cathode material.
In the field of battery industry, the charge and discharge rate is usually used to describe the relationship between charging speed and current size, such as 1 hour to fill the battery rate is called 1C, only 30 minutes rate is called 2C, and so on, more than 1C can be called fast charging. Nowadays, the charging rate of lithium-ion batteries can generally do 1C-3C, the highest can probably go to 5C, but compared to the often 10C discharge rate is still very far from natural.
In addition to the maximum charge rate has a bottleneck, different SOC (State of Charge, that is, the state of charge, that is, the remaining power) under the battery can withstand the charge rate is also different. Generally speaking, the characteristics of the battery in the charging process is roughly similar to the above graph, the charging rate will follow the rhythm of slow - fast - slow. Generally when the SOC reaches 90% or more, the internal resistance of the battery will rise significantly, making the charging rate slow down. If you pay attention to most of the EVs on sale today, you will find that they will advertise themselves as being able to charge a large percentage of the battery in a relatively short period of time - for example, 1 hour or even 30 minutes - under a specific fast charging state, generally around 80%-90%, that's what it means.
So if you are an electric car user and want to save as much time as possible on charging, try not to use the power to less than 10% at every turn, and charging does not have to be full, it is enough to reach 90% or more, or to be able to meet the mileage you need for the next trip.
