Elon Musk "slapped in the face" Zeng Yuqun: The 4680 battery is in smooth mass production and supports megawatt fast charging.

Elon Musk is truly all - around!

It's already remarkable that Tesla has been leading the autonomous driving industry for a long time. Now, it has also returned to the first echelon in electrification:

An accidental disclosure in a North American regulatory document revealed Tesla's latest battery technology, uncovering a well - kept secret:

Tesla's megawatt fast - charging technology has been mass - produced and installed in vehicles.

It uses the latest second - generation 4680 battery...

Zeng Yuqun, the king of the battery industry, who once taught Musk face - to - face and asserted that the 4680 battery wouldn't work, has been "slapped in the face" by Musk's technology and mass - production achievements.

Tesla's Megawatt Fast - Charging Technology Unexpectedly Exposed

The source of the news is a public document submitted to the California Air Resources Board (CARB).

Originally, this document was intended to disclose the battery capacity information of Tesla's newly mass - produced second - generation heavy - duty truck, the Semitruck. However, upon closer inspection, Tesla's latest battery technical parameters were also revealed:

The Tesla Semitruck offers two battery versions:

Long - range version: Usable battery capacity is 822 kWh, estimated range is 500 miles (about 805 kilometers), peak power is 800 kW, and it supports 1.2 MW super - charging.

Standard - range version: Usable battery capacity is 548 kWh, estimated range is 325 miles (about 523 kilometers), peak power is 525 kW, and it also supports 1.2 MW super - charging.

For reference, the battery capacity of the long - range all - wheel - drive versions of Model 3 and Model Y is about 75 - 80 kWh — the battery pack energy of the Semi long - range version is approximately 10 times that of passenger cars.

However, the weight of Model 3 and Model Y is less than 1/20 of that of the Semitruck.

Behind this is the combined effect of aerodynamic optimization, the efficiency curve of the three - motor system, and weight - reduction measures in mass - production design. In terms of energy consumption, the actual energy consumption of the Semi is about 1.7 kWh/mile, and it can travel about 0.6 miles per kilowatt - hour, significantly better than the 0.4 - 0.5 miles/kWh of common electric heavy - duty trucks in the current industry.

In terms of charging efficiency, the peak power can reach 1.2 MW (i.e., 1200 kW) — Tesla's version of megawatt fast - charging.

Calculated based on the 822 kWh battery of the long - range version, at a peak power of 1.2 MW, theoretically, about 60% of the battery can be charged in 30 minutes — which is exactly the duration required by U.S. traffic regulations for drivers to take a mandatory break.

That is to say, the charging time of the Semi is completely aligned with the statutory rest time. The vehicle can be recharged while the driver takes a break, without consuming additional operating time.

From these points, it can be seen that the battery system of the Semi is not simply an enlarged version of the passenger - car solution but is a targeted engineering design based on the actual working conditions of Class 8 heavy - duty trucks.

Comparing Tesla's own battery product line vertically, the improvement of the solution installed on the Semi is quite obvious.

The energy density of the first - generation 4680 battery (used in the Model Y produced at the Texas factory) is 244 Wh/kg, and the peak charging power is about 250kW, corresponding to the V3 super - charging pile. The second - generation 4680 battery, the Cybercell, has an energy density increased to 272 Wh/kg, a 11.5% increase; the supported charging power has jumped to 1200kW, corresponding to the V4 super - charging and megawatt charging piles.

Comparing horizontally with industry competitors, BYD's second - generation blade battery was mass - produced in 2025 and is installed in models such as the Han L. Its system energy density is about 190 Wh/kg (the data at the cell level is different), and it supports a peak charging of about 1500kW, using a dual - gun super - charging solution.

The fourth - generation Shenxing battery just released by CATL has a nominal energy density of about 260 - 280 Wh/kg, and the peak charging power is also claimed to reach 1200kW. However, the key difference is that the fourth - generation Shenxing is expected to be put into mass production at the end of 2026 and is currently a product in the production - line debugging stage.

The conclusion is clear: After a few years of dormancy in the three - electric technology, Tesla has made a comeback and is in the first echelon with BYD. In terms of absolute values, it is slightly more conservative than BYD.

Importantly, Tesla's megawatt fast - charging and second - generation 4680 are not laboratory prototypes or products announced at press conferences but are mass - production technologies already installed in the Cybertruck and Semitruck.

From this perspective, Tesla is about one year ahead of CATL.

After all, the third - generation Shenxing battery just released by CATL is still a future product and will be put into mass production at the earliest by the end of 2026.

This is actually the most powerful counter - attack from Musk after Zeng Yuqun "taught him how to do things" face - to - face.

How Did Tesla Achieve This?

The breakthrough of the second - generation 4680 battery is not a single technological point but the result of simultaneous progress in physical design, electrochemical system, and manufacturing process.

The laboratory at the University of California, San Diego conducted a precise disassembly and electrochemical test on the Cybercell battery cell, revealing the real source of the performance leap.

First and most directly, it comes from the "physical dividend" brought by the weight reduction of the shell.

In order to ensure the structural strength of the 46 - millimeter large - diameter cylindrical battery, the shell thickness of the first - generation 4680 was as high as 0.6 millimeters, which was a typical case of "over - engineering". The second - generation battery cell directly reduced the shell thickness to 0.35 millimeters, a reduction of about 42%.

This is quite radical in engineering — for a 46 - millimeter - diameter battery with a shell wall of only one - third of a millimeter, it has to withstand winding stress and packaging pressure, which is an extreme challenge to the steel stamping process.

However, the benefits are also very direct: the thinner shell releases more internal space for active materials, and the weight of non - active substances is significantly reduced. This single improvement contributes to an increase in energy density of about 20 Wh/kg.

In other words, without changing any chemical formula, Tesla has achieved a nearly 10% performance gain just by improving manufacturing precision.

However, physical thinning alone is far from enough. The upgrade of the electrochemical system is the real core technological breakthrough.

The cathode material of the second - generation battery has been upgraded from NMC 811 (81% nickel, 12% cobalt, 7% manganese) in the first - generation to NMC 955 (91% nickel, 5% cobalt, 4% manganese) — for every one - percentage - point increase in nickel content, the battery capacity will respond positively, and a nickel content of 91% has reached the scientific frontier of current mass - produced high - nickel cathodes.

At the same time, the cobalt content has been reduced to 5%, which not only reduces the risk of relying on cobalt mines in places like the Congo but also dilutes the material cost.

A key verification logic here comes from the change in electrode thickness:

Actual measurements show that the thickness of the anode has only decreased from 250 microns to 240 microns, a decrease of only 4%; however, the thickness of the cathode has decreased sharply from 180 microns to 150 microns, a decrease of 17%.

In a lithium - ion battery, the lithium - ion capacity of the anode and cathode must be strictly matched. The significant reduction in cathode thickness while still being able to carry the same total amount of lithium ions — the only explanation is that the density of active substances in the cathode material itself has made a qualitative leap.

This chemical improvement contributes an additional energy density of about 10 Wh/kg. The combination of these two parts exactly explains the leap in energy density from 244 to 272 (Wh/kg) of Tesla's second - generation 4670 battery.

Beyond energy density, megawatt fast - charging also depends on the innovation of the entire battery pack structure and process.

The biggest enemy of high - power charging is the heat generated by internal resistance. The second - generation 4680 battery has made multiple resistance - reduction optimizations in its mechanical structure.

First, the biggest difference from the first - generation 4680 is that the anode copper foil is directly welded to the bottom cover, eliminating the intermediate interface of the traditional current collector.

Second, the aluminum cathode current collector has been changed from a slotted design to a solid disk, increasing the electron flow area, and the reduction in electrode thickness significantly reduces the ionic resistance of lithium - ion diffusion in the solid phase.

The combination of these three improvements significantly reduces the heat generation of the battery cell during high - rate charging and discharging. This is why although the charging speed of the Cybertruck is currently limited by software to the "middle level in the industry", the hardware has reserved much higher potential — once the V4 super - charging pile is unlocked, the lower internal resistance will support a more aggressive charging curve.

At the production process level, currently, the second - generation 4680 only uses the dry - process for the anode, while the cathode still uses the traditional wet - coating process.

Here is an explanation of the dry - process. It is a "revolution" rather than an "evolution" of the traditional battery manufacturing method. It omits the intermediate links with the highest energy consumption and the most expensive equipment, fundamentally subverting the cost and speed of battery manufacturing.

You can simply understand the dry - process as "directly pressing dry powder into an electrode", just like directly pressing dry flour into shape instead of the traditional method of adding water, stirring into dough, and then baking it in an oven.

It is conservatively estimated that the manufacturing cost is reduced by about 30%, the comprehensive cost is reduced by 10% - 20%, and the production efficiency is 7 times that of the wet - process.

The all - dry process means that the second - generation 4680 is far from reaching the performance limit of current lithium - ion batteries, and Tesla has more technological explorations in reserve.

For example, the silicon - based anode can increase the energy density to 300 Wh/kg and shorten the charging time, and it is expected to be introduced within 1 - 2 years; the asymmetric lamination technology can simultaneously improve the energy density and charging speed, and it is conservatively estimated to increase the energy density by another 35 Wh/kg; the lithium - doping technology can theoretically reach 330 Wh/kg...