Keyword search: battery plant , lithium battery factory , power bank works , lifepo4 battery mill , lithium forklift battery manufacturer

At present, the important focus of the industry on batteries is to reduce their cost, increase their capacity, and at the same time, hope that the lifespan of batteries does not decrease too much to meet the daily needs of consumers. It sounds very idealistic.

Zhang Hua would like to remind you that if you see a battery with particularly strong performance in any aspect, you must reflect on what the cost is.

In terms of the performance of power lithium batteries, we currently prioritize energy density and lifespan, followed by the speed of charging and discharging and the response to temperature. The usual cost of increasing energy density is a decrease in the cycle life of the battery and a decrease in the charging and discharging speed.

Zhang Hua takes Tesla as an example. For example, compared to BYD's lithium iron phosphate battery, Tesla's battery does have a higher energy density, but its cycle life is about twice that of lithium iron phosphate.

Comparison of cycle life between Tesla 18650 and BMW i3 batteries

Wait a minute. Tesla has a high range, high battery energy density, and can be charged slowly or quickly, while also decaying very slowly.

Tesla's range decay map has been widely disseminated.

You can see from the curve in the graph that after driving 200000 kilometers, Tesla's range can still maintain between 90% and 95% of the initial range. This is statistical data from 286 ModelS car owners. In the figure, car owners evaluate the battery decay using their measurable unit of "range".

There's no problem with this. However, the range represents the distance that the vehicle can travel during a charging and discharging process. The cycle life represents how many times a battery can be charged and discharged during its effective life cycle.

Let's do a rough math problem. Similarly, running 200000 kilometers requires Tesla to charge and discharge 500 kilometers at a time, with 400 charges and discharges required to complete the entire journey. Other electric vehicles need to charge and discharge 1000 times to complete the entire journey of 200 kilometers at once.

Simply put, it is the total battery life cycle range=single range ✖️ Cycle life. That is to say, although the cycle life of Tesla batteries is not as excellent, they can run a higher range in one charge and discharge. Therefore, in the battery life cycle, Tesla can run a higher total range than its competitors.

So, the result we see is that Tesla's batteries are not prone to decay, which is widely praised by car owners. However, this does not mean that Tesla batteries have a longer cycle life.

The battery structure is a key issue in the penetration cycle life

How is the cycle life of a battery affected? Firstly, let's take a look at how batteries are charged and discharged.

The discharge process of lithium-ion batteries

The charging and discharging process of lithium-ion batteries is the movement of lithium ions. Academically speaking, lithium ions play two important roles: insertion and extraction.

Lithium ions are embedded in the battery structure, and during each movement, they must escape from the original structure and run to the other side. Zhang Hua made an analogy, it's a bit like you're moving a bunch of things from one room to another.

Whether discharging or charging, lithium ions run from one pole of the battery to the other.

The understanding of battery life should be based on the understanding of battery structure. During the charging and discharging process, the less lithium ions participate in each movement, the less damage to the structure. The slower the lithium ions participate in each movement, the less damage they cause to the structure. If the lithium-ion runs almost enough and continues to be extracted from it, it will cause damage to the battery.

The more unstable the structure is, the more it is damaged, and the cycle life will naturally deteriorate. So, we usually emphasize that the charging and discharging of lithium-ion batteries should be shallow and not challenge the battery's "limits".

Secondly, let's care about the materials. Different electrode materials have different battery structures. When we increase the energy density of the battery by changing the proportion of electrode materials, the cycle life of the battery also changes. For example, Tesla's NCA battery has a worse cycle life than BYD's lithium iron phosphate battery.

Tesla uses silicon carbon negative electrodes on 21700 batteries, and the more silicon is added, the more likely the battery structure is to be damaged, and the more likely its cycle life is to be affected. The influence of electrode materials on the lifespan is also based on the battery structure.

Finally, the temperature is also the same. Low temperatures below zero degrees can also have a negative impact on the structure of batteries, and even permanent damage.

Therefore, the charging and discharging process (depth/speed), battery material, and temperature can all affect the cycling life of the battery by influencing its structure.

By the way, we can understand the purpose of the battery management system. The core purpose of a battery management system is to ensure the stability of the battery in terms of performance and lifespan. So, the battery management system is important for two things, one is to manage the interaction between the internal environment and the outside world, that is, to manage the charging and discharging process of the battery. One way to manage the interaction between the external environment and the battery is through temperature (thermal) management.

Some people say that the displayed data on the vehicle shows that the battery consumption is 0, but the car can still run for a while, which is also a management measure to prevent excessive battery discharge depth.

Large batteries can be more flexible during the charging and discharging process

How much charge and discharge is more suitable for batteries?

Let's recognize three words. One is SoC (State of Capacity), which represents the current capacity of the battery. One is DoD (DepthofDischarge), which represents the depth of battery discharge. Another one is C (Current), which represents the rate of charge and discharge of the battery.

Depth and speed are important influencing factors in the charging and discharging process.

SoC and DoD

First, let's take a look at the depth.

The depth of battery discharge is related to the capacity of the entire battery. For example, Tesla's battery is 90 degrees Celsius, while other electric vehicles are 45 degrees Celsius. Similarly, driving 100 kilometers for 5 seconds, Tesla uses 0.1% of its battery capacity, while other electric vehicles use 0.2% of their battery capacity, resulting in varying degrees of damage to the battery.

The effect of discharge depth on cycle life, source: StephenGrinwis; That is to say, in-depth investigation is not about absolute values, but about capacity ratios. Large batteries have a certain advantage here.

In terms of speed, the higher the rate of charge and discharge, the shorter the time required and the shorter the cycle life. Starting quickly and slowly in the same car results in different battery consumption and damage. Rapid acceleration is equivalent to the rapid discharge of a battery.

Is the fast charging we are looking forward to causing damage to the battery? There must be, but what we are more concerned about is how much this loss is.

If the slow charging cycle life of a typical charging station is 700 times, and the matching fast charging cycle life is 500 times, it will not have a significant impact on normal driving. If the cycle life of slow charging is 700 times and the cycle life of fast charging is 100 times, then forcing fast charging is not very meaningful. This is also why it is not recommended to use a Macbook charger to charge an iPhone.

When it comes to different car models, due to Tesla's large battery, the current is smaller at the same acceleration, which is equivalent to a slow down process. From a slow down perspective, the battery decays more slowly.

If on this basis, the charging and discharging speed of the battery is increased by 25%. So Tesla's 25% growth rate is 0.1% of 25%, while the 25% growth rate of other electric vehicles is 0.2% of 25%, the results are different.

During the driving process, Tesla consumes a low proportion of battery capacity during the same charging and discharging process, which in turn reduces the negative impact on cycle life. So, Tesla uses large batteries to compensate for the disadvantage of cycle life. Although Tesla batteries have fewer usable times, they run far. That's also why, despite Tesla's low cycle life, users perceive that Tesla's batteries are sufficient for use.

This is what impressed me the most during my communication with Zhang Hua.

It seems that the NCA batteries used by Tesla have many shortcomings, but Tesla overcame these shortcomings in battery performance through the accumulation of battery cells. We thought we were doing addition, but it's not the simple addition you think.

Of course, Zhang Hua does not advocate blindly increasing battery life and sacrificing other battery performance. After all, battery life is the easiest to evaluate, and other battery performance requires car owners to invest a lot of time to experience.

However, in the current charging environment, driving the interest of car owners in electric vehicles, range is an unavoidable issue. Unless we want to explore other new energy sources, we can continue discussing this topic next time.

Finally, Zhang Hua's suggestion is that the depth of charge and discharge for batteries is usually between 20% and 80%.

How strong is Tesla's battery life?

Garage 42

Tesla fans have always firmly believed that Tesla's technological level is far ahead (no, this word can no longer be used casually).

Engineers from traditional companies argue that Tesla is not as impressive as you think. Fans are not satisfied, so why hasn't your battery life surpassed Tesla? The engineer didn't want to explain, but secretly muttered that our energy density is also very high, but the cost is too high and no one is using it.

Engineers feel that fans don't understand anything, and fans feel that engineers are all stubborn. The labeling of two groups towards each other is becoming increasingly distant from the multidimensional restoration of the essence of things. The opposition on both sides often confuses me, why can't we communicate well.

More and more people are asking me this question, how strong is Tesla's battery life. If you can't speak clearly in a few words, why not try writing. Of course, I am not a professional engineer, please feel free to point out any mistakes.

Before attempting to explore this issue, let's first define the prerequisites and sort out several basic concepts.

1. Vehicle endurance is not only related to the battery, but also to the operation under different working conditions. Due to the complexity of the latter issue, it is important to discuss batteries today.

2. The most important performance parameter of a battery is energy density, which includes volumetric energy density (Wh/L) and mass energy density (Wh/kg). We talk more about mass energy density (Wh/kg) in batteries, which determines the amount of energy stored per unit weight of the battery.

3. The energy density of a battery often points to two different data points, one is the energy density of the battery system and the other is the energy density of the battery cells.

A cell is the smallest unit of a battery system, also described as a single cell. You can understand it as a single battery, for example, a fifth battery. M battery cells form a module, and N modules form a battery pack, which is the basic structure of automotive power lithium batteries. Some people directly refer to battery packs as battery packs.

NissanLeaf uses a soft pack battery, which consists of cells, battery modules, and battery packs from top to bottom.

It's actually a very simple formula, battery pack=N module=N (M cells).

4. Due to the fact that the battery pack is related to the final shape of the battery and the layout of the vehicle, most manufacturers choose to purchase battery cells and make their own battery systems. The energy density of a battery system is related to the selection of battery cells. For example, cylindrical batteries have a relatively low energy density due to the small capacity of a single cell and the complex structure of the battery system. Under the premise that a single cell has an advantage in energy density, the energy density of the battery system will be relatively low. (Conclusion reference from McKinsey's report)

The battery supply chain strategy of electric vehicle manufacturers, original image from McKinsey, translated from garage 42.

5. Structurally, there are three important types of battery cells: square shell batteries (Prismatic), pouch batteries (Pouch), and cylindrical batteries.

From left to right are cylindrical batteries, square shell batteries, and soft pack batteries.

From the classification of raw materials, there are different types of battery cells, such as lithium iron phosphate, nickel cobalt manganese (NCM), and nickel cobalt aluminum (NCA). The material here mainly refers to the positive electrode material. Among the influences of raw materials, the positive electrode material has a significant impact on the energy density of the battery cell.

Graphite is commonly used as the main negative electrode material, and the current mainstream research direction is exploring the commercialization of silicon carbon negative electrodes.

The different structures and raw material compositions of battery cells have an impact on their energy density.

I will summarize the key points of the above content again.

When discussing the impact of batteries on vehicle range, it is important to discuss the energy density of the battery system and the structural arrangement of the overall weight. The energy density of the battery system is determined by the selection of positive and negative electrode materials and structures of the battery cells.

After establishing a basic understanding of the framework, we can now discuss the details for specific vehicle models.

Let's look at it from big to small.

Firstly, it is the overall structure of the battery pack.

In McKinsey's report, an important conclusion is drawn that the battery system styles arranged on different vehicle structures have a significant impact on the energy density of the battery system.

Regarding this point, let's directly look at the picture and feel it.

Let's take a look at General Motors, an established manufacturer that produced the first mass-produced electric vehicle EV1 in the second wave of electric vehicles.

Lithium ForkLift Batteries ,Ensure Quality

Our lithium battery production line has a complete and scientific quality management system

Ensure the product quality of lithium batteries

Years of experience in producing lithium forklift batteries

Focus on the production of lithium batteries

WE PROMISE TO MAKE EVERY LITHIUM BATTERY WELL

We have a comprehensive explanation of lithium batteries

QUALIFICATION CERTIFICATE

THE QUALITY OF COMPLIANCE PROVIDES GUARANTEE FOR CUSTOMERS

MULTIPLE QUALIFICATION CERTIFICATES TO ENSURE STABLE PRODUCT QUALITY

Providing customers with professional and assured products is the guarantee of our continuous progress.

Applicable brands of our products