How strong is Tesla's battery life?

Tesla's fans have always firmly believed that Tesla's skill level is far ahead (not right, the word can no longer be used casually).

The engineers of the traditional enterprises came out to refute that Tesla was not as strong as you thought.

Fans dissatisfied, then how does your life last longer than Tesla?

Engineers don't want to explain, but they are privately squatting. Our energy density is also high, but the cost is too high to be used.

Engineers feel that fans don't understand, and fans feel that engineers are stubborn. The two groups are thus labeling each other, and it is getting farther and farther away from the multi-dimensional nature of things.

The opposition on both sides often puzzles me, why can't I communicate well?

More and more people are asking me this question, how strong Tesla's battery life is. If you can't say a few words, it's better to try to write it. Of course, I am not a professional engineer. If there is something wrong, please correct me. Before trying to explore this issue, we first define the preconditions for this problem and sort out several basic concepts.

1. In addition to the battery, the vehicle life is related to the operation under different working conditions. Because the latter problem is more complicated, today mainly talk about batteries.

2. The most important performance parameter of the battery is energy density. The energy density has volume energy density (WH/L) and mass energy density (WH/kg). What we talk about more on the battery is the mass energy density (WH/kg), 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, one is the energy density of the battery system, and the other is the energy density of the battery.

The cell is the smallest unit of a battery system and is also described as a single cell. You understand it as a single battery, for example, a fifth battery. M batteries form a module, and N modules form a battery pack. This is the basic structure of the vehicle power battery . Some people directly call the battery pack a battery pack.

▲ Nissan Leaf uses a soft pack battery , from top to bottom for the battery, battery module and battery pack.

In fact, it is a very simple formula, battery pack = N · module = N · (M · battery).

4. Since the battery pack is related to the final shape of the battery and the vehicle layout, most manufacturers will choose to purchase the battery core and do the battery system by themselves. The energy density of the battery system is related to the selection of the battery core. For example, the cylindrical battery has a small capacity and the battery system has a complicated structure. Under the premise that the energy density of a single battery is dominant, the energy density of the battery system is relatively low. (Conclusions refer to reports from McKinsey)

▲ Electric vehicle manufacturer's battery supply chain strategy, the original picture from McKinsey, the translation of the 42nd garage.

5. According to the structure, there are three main types of batteries: Prismatic, Pouch and Cylindrical.

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

From the division of raw materials, the batteries are of different types such as lithium iron phosphate, nickel cobalt manganese (NCM) and nickel cobalt aluminum (NCA). The materials here mainly refer to the positive electrode materials. In the influence of raw materials, the positive electrode material has a great influence on the energy density of the cell.

The anode material is generally graphite-based, and the current mainstream research direction is to explore the commercialization of silicon-carbon anode.

The structure of the cell and the composition of the raw materials have an effect on the energy density of the cell.

I will summarize the main points above.

When we discuss the impact of batteries on vehicle cruising range, the main discussion is the structural arrangement of the energy density and overall weight of the battery system. The energy density of the battery system is mainly determined by the positive and negative materials and structure selection of the battery.

After establishing a basic understanding of the framework, we can now talk about the details for specific models. We look at it from big to small.

First of all, it is the overall structure of the battery pack.

In the McKinsey report, it is important to conclude that the battery system styles placed on different vehicle structures have an important impact on the energy density of the battery system.

For this, we look directly at the picture.

Let’s take a look at the second wave of electric vehicles, which produced the first veteran manufacturer of the first-generation electric vehicle EV1.

The following picture, from left to right, is the first generation Volt, the second generation Volt, Spark EV and the latest Chevrolet Bolt battery system. Among them, Volt is a plug-in hybrid model, Spark EV and Bolt are pure electric models, and Spark EV is the first mass-produced electric vehicle that has been launched since the EV1 was discontinued.

Take a look at the battery layout and battery structure of the Spark EV.

▲ Chevrolet Spark EV

The 2014 Spark EV uses a lithium iron phosphate battery supplied by A123 with a capacity of 21.3 kWh.

The 2015 Spark EV battery was changed to LG Chem, 96 groups, each group of 2 batteries, each battery 27Ah, 3.75V, a total of 192 batteries, battery capacity of 19.44kWh (192x27Ahx3.75V).

The entire battery system has a volume of 135L and a total weight of 215kg, which is 39kg less than the old model. Based on the above data, the energy density of the volume and mass of the 2015 SparkEV battery system is 144Wh/L and 90Wh/kg, respectively.

After the battery is replaced, the cruising range of the two cars under the EPA standard is 132km. That is to say, although the battery capacity and weight are reduced, the energy density of the new battery is increased, and the cruising range of the vehicle remains unchanged. But the life of more than 100 kilometers obviously does not make much sense.

What should I do if I want to continue to improve my vehicle life?

Either continue to increase the energy density of the cell, or just install a little more cells. Simply put, either continue to use this platform or you have to change it.

The old platform transformation (AEP: Adapted Electric Platform) is divided into two types, one is the old design based on the old platform, and the other is the new design based on the old platform. Spark EV belongs to the former, using the GammaII platform, Chevrolet Bolt belongs to the latter, based on the GammaG2SC platform design.

▲ Chevrolet Bolt

Look, the naked eye, the battery structure has become flatter, the battery has increased in size, and more batteries can be installed. That's right, Chevrolet Bolt's batteries have increased to 288, still 96 groups, but each group has increased to 3 batteries.

The cells are supplied by LG Chem, each cell 55Ah, 3.75V. The battery capacity is nearly 60kWh (actually 288x55Ahx3.75V=59.4kWh).

The battery has a volume of 285L and a total weight of 435kg. The battery system has an energy density of 246Wh/L and 137Wh/kg, and the EP has a cruising range of 383km.

It can be seen that from Spark EV to Bolt, the number of cells has increased by half, the battery volume has increased by 0.7 times, the battery weight has doubled, the energy density of the battery system has also increased by half, and the vehicle cruising range has tripled.

The redesigned vehicle chassis is more conducive to the layout of the battery system.

In addition to the historically representative universal electric car (Tesla has also borrowed from the design of the EV1), another world-renowned best-selling electric car is the Nissan Leaf.

It is said that the battery arrangement of Spark EV is cramped, but the shape is fairly flat. On the Nissan Leaf, the soft-formed cells, which were originally very regular in shape, were stacked together and arranged in an irregular shape to accommodate the seat structure on the vehicle.

In a battery pack, there are horizontally placed, and placed vertically, it is almost obsessive-compulsive. It does not reflect the Virgo traits that the Japanese should have.

▲Nissan Leaf

Nissan Leaf said that it is his own EV platform, but it is also done with reference to Tiida. After so many years, the layout of the power system has been adjusted, but the shape and position of the battery has remained basically unchanged.

▲ Nissan Leaf new and old models contrast

After learning about the Bolt battery structure, you can see if you can guess that Leaf's battery life may be limited.

Nissan Leaf shares three batteries. From 24kWh to 30kWh to 40kWh, the number of batteries is always the same, it has been 192, and the EP mileage has increased from 135km to 172km to 241km.

However, Bolt has been feeding 400km!

Of course, if you want to change the standard, the data looks fine.

▲ Nissan Leaf's battery life under the JC08 standard

After the conclusion is over, look at the specific data.

The 24kWh battery uses AESC lithium manganate LMO cells, each with 33.1Ah, 3.8V. The total weight of the cell is 151.1 kg, and the energy density of the cell is 317Wh/L and 157Wh/kg.

The 30kWh battery uses a nickel-cobalt-manganese (NCM) battery with a weight gain of 21kg at 24kWh. The cell has an energy density of 396Wh/L and 174Wh/kg.

▲ Nissan Leaf battery changes

In 2017, Nissan Leaf added a 40kWh battery with an EP range of 241km. Yes, it is already 2017.

When GM claimed that it would lose $9,000 per Bolt, it wouldn’t know if Nissan would save money or save money or save money.

The masterpieces of the United States and Japan have been seen, and we are now looking at Germany.

Many people are familiar with the MQB platform of Volkswagen. E-Golf is the product of the MQB platform. E-Golf is the popular e-up! The second mass-produced electric car was introduced later.

▲ Volkswagen E-Golf

Is there a familiar feeling that the irregular battery structure that was born under the traditional internal combustion engine platform has come again.

The E-Golf's battery was also equipped with a pair of small wings on the Volt's T-shaped structure (the T-shaped structure was originally derived from the universal EV1 model) in an attempt to make a little space struggle.

However, the data shows that the 2015 e-Golf's EP voyage is 134km.

The 2015 e-Golf uses Panasonic Sanyo's square-shell battery with a battery capacity of 24.2 kWh and a weight of 330 kg. The total is 27 modules, 264 batteries (88s3p), each battery 25Ah.

▲ Volkswagen e-Golf battery

In 2017, Volkswagen replaced the e-Golf battery supplier. The latest 35.8kWh battery comes from Samsung SDI, with a 37Ah battery and an EP range of 201km.

There is still a long road.

Another factory in Germany that can't be ignored is the legendary BMW that has trained two heavyweight battery suppliers in Samsung SDI and Ningde era.

Finally we talk about the BMW i3. The BMW I-series is a newly designed product line. It can be seen from the i3's battery structure. It has a very flat rectangular shape. The battery case is like a drawer with 96 batteries.

▲ BMW i3

The i3 old battery capacity is 22kWh, the EP has a cruising range of only 130km, and the 60Ah battery is used.

The i3's new cell has the same size and uses 94Ah and 3.7V nickel-cobalt-manganese (NCM) cells from Samsung SDI with cell density of 357.4Wh/L and 173.9Wh/kg. The total battery capacity is 33kWh and the EP's cruising range is increased to 182km.

It seems that the flatness of the light structure is useless, and it is impossible to install a large battery.

Mercedes-Benz, the first Smart and B-Class electric power systems were supplied by Tesla. After the replacement, there was no major change in the structure, and the space was limited.

▲ Mercedes-Benz Smart

▲ Mercedes-Benz B-Class

▲ Renault Zoe

After reading the electric car products of these traditional car companies, we finally look at Tesla's chassis. This should be the map that everyone is most familiar with. There is a sense of fullness with a full battery.

▲ Tesla Models

Tesla has different battery versions from 60kWh to 100kWh. In the middle, the 18650 battery was upgraded from 2.9Ah to 3.1Ah. The 70kWh version was upgraded directly to 75kWh while maintaining the same structure.

Let's take a look at Tesla's battery life data under the EPA standard.

▲ Tesla Models's cruising range, screenshot from Wikipedia

As you can see in the screenshot, taking Models as an example, the Tesla EPA standard has a range of more than 300 to more than 500 kilometers. As can be seen from the latest published EPA data, the model 3 long battery life has reached 499 kilometers.

From the point of view of the marketed products, it is completely a victory of the crushing level.

Therefore, Volkswagen announced the creation of a new electric vehicle MEB platform, the technology of the MEB platform will be shared within the Volkswagen Group. This platform is like this.

▲Volkswagen MEB platform

Mercedes-Benz's new electric car platform EQ is like this.

▲ Mercedes-Benz EQ platform

The old platform that can't fit a big battery is destined to be a transition.

Of course, the creation of a new platform often requires tens of billions of investment. When the electric vehicle is only a niche market, the conservative performance of the traditional car company is very normal. This also brings Tesla's opportunity points and leading market advantages.

The performance comparison of commercially available products is actually compared at the product level.

Products are actually the embodiment of a comprehensive corporate strategy. To consider the market size, brand positioning, but also to calculate the cost and price. For example, a low-end brand, without the brand's premium pricing power, can't easily build a luxury electric car like the price of a million-level price like Tesla.

When you define yourself as the leader of the future market, or followers, you also define whether your product must apply the latest and best technology. And this is what technology enthusiast value most.

In order to more objectively compare the differences between the various products, now we talk about the technical level, that is, from the battery system to talk about the battery.

From the evolution of the cell in the previous section, you may notice that everyone started using nickel-cobalt-manganese (NCM) batteries. NCM is the cathode material of the battery. According to the cathode material, there are three main types of batteries, lithium iron phosphate, nickel cobalt manganese (NCM) and nickel cobalt aluminum (NCA).

Lithium iron phosphate batteries are safer, have lower energy density, and are more widely used on passenger cars. BYD took the lead on the exploration of ternary lithium batteries because of the bet on the lithium iron phosphate route. In the passenger car, we mainly know two kinds of batteries, NCM and NCA. Tesla's Panasonic cylindrical battery is the NCA material.

▲NCM battery composition

In order to increase the energy density of the battery, the first thing to do is to increase the specific capacity of the positive electrode material of the battery. The higher the nickel content, the higher the specific capacity of the cell. In addition, because the cobalt price is too high, increasing the proportion of nickel and reducing the proportion of cobalt, the cost of the battery can be successfully reduced, which is also an important reason for the development trend of high nickel batteries.

And our common NCM111/523/622/811 refers to the ratio between these three elements. In other words, the NCM811 is currently the battery with the highest proportion of nickel.

▲ BMW's battery roadmap

We can see from BMW's battery roadmap that NCM will gradually adjust from 111 to 811. 2018 BMW i3 will use Samsung SDI's NCM622 battery, and until 2021, BMW will be on i5. Apply NCM811 batteries.

The Mercedes-Benz EQ platform will use SKinnovation's NCM811 battery in the third quarter of 2018.

According to LG Chem's data, the models that plan to use their latest 811 batteries have the following:

Nissan Leaf E-Plus (60kWh version)

Modern Kona EV

Hyundai IONIQ Electric (battery upgrade)

Kia Niro EV

Second generation Renault Zoe (2019)

Volkswagen ID (2019)

Opel CorsaEV (2019)

Peugeot 208EV (2019)

That is, the model with the NCM811 battery will be seen as early as 2018.

Although these manufacturers do not provide energy density data for the current NCM811 cells, we can look at the data provided by Solid Power.

▲Source: Solid Power

With NCM811 positive electrode and graphite negative electrode, it can reach 255Wh/kg and 536Wh/L energy density.

According to official CATL data, the energy density of their batteries can now reach 240Wh/kg.

▲Source: CATL US official website

In addition, official data from BYD shows that the energy density of BYD NCM batteries can now reach 200Wh/kg.

▲Source: BYD's public speech

Tesla's current energy density of 18650 cells is about 250Wh/kg. On Model 2's 2170 cells, Tesla will use a silicon-carbon negative electrode to increase the cell's energy density to 300Wh/kg.

That is to say, simply comparing the energy density of the cell, other manufacturers can reach the energy density level of the Tesla 18650 cell, but on the Model3 that has already begun to deliver, Tesla is leading.

In addition to increasing the proportion of nickel on the positive electrode material, the use of silicon carbon in the negative electrode material is also an industry recognized direction. Because the theoretical energy density of graphite is 372mAh / g, and the theoretical energy density of silicon negative electrode is as high as 4200mAh / g.

There is only a problem of expansion of the silicon negative electrode material, which may result in loss of battery capacity and affect the cycle life of the battery. Currently on the production of batteries, only Tesla announced the successful application of silicon carbon anode materials.

▲ battery route evolution, source: Solid Energy

In the "Promoting Action Plan for the Development of Automotive power battery Industry", the Ministry of Industry and Information Technology proposed that the energy density of the new lithium-ion power Dongchi battery should exceed 300Wh/kg, and the energy density of the battery system should reach 260Wh/kg. By 2025, the energy of the battery system The density should reach 350Wh/kg.

At present, NCM811 has increased the proportion of nickel to a level that is difficult to increase significantly. The use of silicon carbon anodes or the study of different cathode materials will be a lifting point. And to more than 300Wh / kg, the technical breakthrough of solid-state batteries will become the key.

At the product level, car companies can already apply newer and better technologies, but because the early electric vehicle market is too small, car companies have not invested large amounts of money in the development of new platforms for electric vehicles. The innate factors of the platform of internal combustion engines have made it impossible. Load a large battery.

▲ Volkswagen's endurance schedule

▲ Nissan's endurance schedule

▲ Renault's endurance schedule

On the other hand, market research by research companies shows that three or four hundred kilometers of battery life is enough to meet the needs of current users. Old-fashioned giants, no, experienced veteran car companies do not want to risk the introduction of costly models.

They have long been accustomed to this in the market for traditional internal combustion engine models. When startups are rushing to attract attention with gorgeous data, they are not in a hurry, while slowly advancing their new platform plans, while trying to attack competitors in public opinion.

So, where is Tesla's battery life?

First, at the technical level of the battery core, we have chosen different technical routes, and the energy density at the level of 250Wh/kg is not divided. However, Tesla successfully broke through 300Wh/kg on silicon carbon anode materials and took the lead in the industry.

Secondly, due to the lack of historical burdens, Tesla was able to throw away the burden of the chassis of the internal combustion engine, develop a new electric vehicle platform, and gain a high degree of freedom in the layout design of the battery system. It can introduce a battery capacity of 100kWh very early, leading the industry for several years.

Third, with Muske's first-class marketing capabilities, Tesla has succeeded in creating a high-brand positioning that allows it to quickly apply the latest and greatest technologies in the high-priced market segment.

The page contains the contents of the machine translation.