The solid-state battery version of the Zhiji L6 will not exceed 330,000 yuan for pre-sale.
After NIO's 150kWh battery pack was put on the car, Zhiji's 133kWh solid-state battery was also installed with the launch of the Zhiji L6. There are a few keywords about the press conference, including 21,000 rpm motor, quasi-900V fast charging, 133kWh solid-state battery, CLTC pure electric 1,000km, chassis air suspension + CDC, rear-wheel steering, and support for crab mode.
Of course, the focus of our concern is not quasi-900V, nor chassis air suspension and crab mode, which are not technological breakthroughs, although these are also good technical products. But the key point is the battery pack of this car, and the official propaganda caliber of this battery pack is a "solid-state battery". The specific battery pack and model information is that the four-wheel drive model with dual motors can also run more than 1000km at a time, and the battery pack capacity is 133kWh (looking at the data, it is better than NIO's 150kWh battery).
So, is this solid-state battery of Zhiji high-tech? Is it really all-solid-state?
The current technology is still semi-solid
Today's solid-state battery is still only a laboratory product, and there are still many problems, such as the ionic conductivity of the solid-state electrolyte is much lower than that of the liquid electrolyte, and the high impedance of the battery also affects the transmission efficiency of lithium ions. These are all factors that will lead to the increase of the internal resistance of the battery, and the number of charge and discharge cycles is also the low life.
What are the technical highlights of this solid-state battery pushed by Zhiji?
The press conference did not tell a lot of information about solid-state battery packs, but we can start with two key points, the first is the ultra-high nickel cathode material, and the second is the new composite carbon silicon anode. Incomplete statistics, SAIC has at least 6 patented technologies for solid-state batteries, and then one of them is about high-nickel cathode materials, which mentions the implementation case of NCM811, and there is not much mention of high-nickel cathode materials at the press conference, so it is speculated here that Ni90 ternary cathode is now shipped a lot.
And this high-nickel material, most likely the same as the cathode material of NIO's 150kWh battery pack, is the Ni90 ternary cathode, and it is also the most suitable cathode material for solid-state batteries that can be obtained at present.
After that, about the composite silicon carbon anode. The main material is still a composite material system composed of fast-charging graphite + a new generation of nano-scale silicon-carbon composite materials. At present, more than half of the mass-produced carbon silicon anode is the solution of SiOx matching graphite, and the content ratio of SiOx is less than 5%. The purpose is to achieve higher energy density and fast charging performance, and if it does, it will run the same range as NIO's 150kWh battery (power density of 360Wh/kg) with a 133kWh battery, which will have a higher power density than the latter.
Key point, what electrolyte is used?
In terms of electrolyte, solid-state batteries must be used, but wetting agents are also mixed into them. It is also because the compactness of the solid is not enough, and there is a gap in the middle of the electrolyte, which will affect the normal transmission of the lithium-ion battery, so it is necessary to add about 10% wetting agent to it, which is equivalent to filling the gap in the middle of the electrolyte with liquid. In this way, this battery is considered solid-state, but it is not all-solid-state, and it is still a semi-solid-state battery.
What is Quasi-900V?
This is also a point mentioned at the press conference, and the promotional caliber is a quasi-900V battery. Judging from the structural diagram, the general structure of the battery pack of Zhiji L6 is basically the same as that of Zhiji L7, which belongs to the same Cell to Pack structure, divided into 3 areas, each area has 68 cells, and the battery pack has a total of 204 cells.
Then, if the upper limit of the voltage of a single cell is about 4.4V and is made in series, then the maximum voltage of the battery pack is about 897V, which is in line with the propaganda caliber of quasi-900V. But what I can't understand is that the charging power is only 400kW, and the charging speed is a little slow.
A few thoughts on charging, and cost
How to solve the points of discharge power, cycle life, cost, and safety. While solid-state electrolytes exert their stability and match higher gram capacity cathode and anode materials, they must also face cycle life and safety issues, as well as costs. But at present, looking at the performance of the pre-sale price of about 330,000 yuan, there should be a new breakthrough on the cost side.
According to the published information, the charging speed of the solid-state battery of Zhiji has not been improved. The contact between the solid electrolyte and the positive and negative electrodes will form a higher interfacial impedance, so the increase in internal resistance affects the charging speed. Therefore, although Zhiji uses the dry solid-state electrolyte layer integrated molding technology to reduce the internal resistance, the charging effect is not good.
About 10%-80% in 20 minutes, it may be a bit far-fetched to say that it is ultra-fast charging. Then it can't be replaced, which may become a pain point after mass production.
Then on the cost level, the semi-solid-state battery cooperated by Zhiji and Qingtao, compared with ternary and lithium iron phosphate, the energy density is increased by 10% in the same weight of PACK. However, the cost can be reduced by 10%-30%, and the cost reduction is still a problem that the supplier needs to solve, and Zhiji did not say that it is a self-developed solid-state battery, so it is not a technological breakthrough, but the advantages brought by mature technology, and improving the yield rate means reducing the cost.
One charge, one price, at least solves the cost problem of solid-state batteries, even if the charging power is low, the charging time is slightly longer, but the cost drops by 10-30%, it should also be able to have an advantage in the market.
Is the current semi-solid state an IQ tax?
From semi-solid to all-solid-state batteries, in addition to gradually reducing the proportion of electrolyte until it is all-solid, the electrolyte begins to be used in a variety of materials, and the anode material must be changed from silicon carbon to lithium metal or lithium-containing alloy. In the process, the separator should be gradually eliminated, and then the energy density should be more than 500Wh/kg.
We will have to wait at least three years before we can iterate to the second generation of solid-state batteries.
The semi-solid-state battery we see now is made of ternary high nickel for the positive electrode, silicon carbon material for the negative electrode, and about 10% wetting agent in the electrolyte, and then the oxide electrolyte is mainly used to form a composite electrolyte. The energy density is currently 360Wh/kg, and the maximum can be around 420Wh/kg.
So let's see, is a ternary lithium battery of about 100kWh better, or a solid-state battery of 133kWh or 150kWh?
From the perspective of cost, technological innovation, and actual use experience, the cost of whether it is Zhiji's or NIO's solid-state battery, compared with the ordinary ternary lithium battery of about 100kWh, the cost cannot be regarded as an advantage. Technological innovation, there must be, but it is only the first generation of products, not to mention qualitative changes, the energy density can be increased to 360Wh/kg, but the energy density of the 100kWh Kirin battery is 255Wh/kg, and the gap has not been widened.
Therefore, in fact, the better choice at this stage is that the battery pack of about 100kWh is more practical and cost-effective. Then, relatively speaking, the battery replacement of solid-state batteries is also more necessary, because outside the cost side, the full charge is indeed not fast enough, and the charging capacity of 4C and 5C is relatively immobile.
After that, there will be a second-generation solid-state battery, no matter who it is, the direction is that the positive electrode will continue to use ternary high nickel and nickel-manganese, and the negative electrode will be matched with a lithium-containing composite anode. Then, the liquid content in the electrolyte was less than 5%, now it is 10%. In terms of technology, things like separators and quasi-separators may disappear completely, and the energy density can reach 400-500wh/kg, which is about double the energy density of ternary lithium batteries. Then, up to the third generation, an all-solid-state electrolyte is used with an energy density of more than 500 wh/kg.
Objectively, it cannot be said that the current semi-solid-state battery is an IQ tax, but it can be said that it is not as suitable as imagined; theoretically, the development of this battery technology, the more it is to use, for example, there has been an obvious breakthrough in energy density since the second generation.