After so many years of development, the endurance of 1000km is still far away?
The development of pure electric vehicles has been driving the direction of development in several areas, including software including batteries. The former goes deeper into the degree of intelligence + driving assistance function; the latter is the battery mileage, and the optimization of the battery energy replenishment experience.
Intelligence is promoted by perception hardware + algorithm, the development is very fast, and the functions gradually realized in recent years have developed from expressways to urban roads. The battery to be talked about later has been promoting the improvement of the mileage and the shortening of the charging time, but the senses given to us by the entire industry are not much changed. A few years ago, the maximum endurance was 300-400km, and now the maximum endurance is 600-700km, even if it is fast charging, it takes tens of minutes to wait.
Without being able to compress the charging time to the same as the refueling time, we began to envision a high-endurance battery.
Battery life exceeds 1,000 kilometers = confidence + strength
The reason for talking about the 1000km battery again is because the American battery startup ONE has achieved a battery driving about 1200 kilometers on the Tesla Model S test vehicle. This startup, the battery company invested by BMW, has once again pulled the 1,000km battery back into view.
ONE company and Tesla Model S test car, the use of their own research and development of modified batteries, the specific use of lithium iron phosphate or ternary lithium or solid-state batteries without instructions, the volume of the battery pack and Tesla's original 103.9kWh ternary lithium battery pack is comparable, but the energy density increased to 207.3kWh. Leaving aside whether its safety can meet the requirements of mass production, the endurance limit of this battery has been verified in terms of technical feasibility.
Judging from the current general cruising range of 600km+, as long as the charging speed is accelerated and the power exchange mode is popularized, the 600km cruising range can already solve the travel needs of most users. Why are there still people who are keen to make the endurance break through 1,000? Just like the W12 and V12 engines in the era of fuel vehicles, the symbolic meaning is greater than the actual significance, and each era must have a "ceiling".
At present, including ONE's Gemini 001, the claim to battery life exceeds 1,000 kilometers is also:
NIO's 150kWh solid-state technology battery, delivered in Q4 2022;
Zhiji car supports nearly 1000km endurance, equipped with Ningde era silicon-doped lithium battery;
GAC Aean, silicon anode graphene-based battery NEDC endurance of 1000km.
The above several enterprises that claim to have a battery life of more than 1,000, without exception, have not used traditional "ternary lithium" and "lithium iron phosphate" batteries. The mileage of the power battery is determined by the energy density of the battery, and the current maximum energy density of lithium iron phosphate is ≥ 160Wh/kg, and the maximum energy density of ternary lithium is ≥ 210Wh/kg.
Want 1000km endurance, with the current technology lithium iron phosphate is far from reachable, relying on ternary lithium can be achieved in theory, but certainly not simply to make the battery pack bigger, heavier, one is the cost problem, the other is that its own weight will also bring pressure to the cruising range.
Choices from the above companies include solid-state (including semi-solid-state) batteries and ternary lithium batteries with a higher proportion of silicon elements incorporated into the negative electrode. Solid-state batteries and silicon-carbon anodes can make the battery range exceed 1,000 kilometers, but these two types of batteries have their own technical difficulties.
Solid-state batteries/silicon element anodes have the ability to break through a thousand
The so-called solid-state battery replaces the electrolyte in the existing battery with a solid-state electrolyte, but most of what we hear so far is still a "semi-solid-state battery" after replacing the solid-state electrolyte with about 5-10% of the electrolyte.
Solid-state lithium batteries and traditional lithium batteries work the same principle, that is to say, the place of lithium ion migration is replaced by electrolyte from electrolyte, and the upgrade of the battery cathode material makes the solid-state electrolyte better adapted, which is conducive to the improvement of battery energy density. This is an advantage, high energy density; secondly, the solid electrolyte has better insulation, avoiding short circuits caused by positive and negative contact and can also be used as a diaphragm.
The first major difficulty of solid-state batteries, the electrolyte from liquid to solid, the choice of solid electrolytes are oxides, polymers and sulfides.
The flexibility of oxide materials is relatively poor, solid-state batteries are solid-solid contact, poor flexibility will increase the interfacial impedance, followed by large-scale mass production is a trouble;
Polymers have the problem of low conductivity, which is several levels lower than the current electrolyte conductivity, and may become semi-liquid at high temperatures;
Sulfide is theoretically the best choice, but it also faces problems such as complex preparation processes, sensitivity to air, and expensive raw materials.
In order to take into account the comprehensive performance of high energy density, high safety and long life, solid-state batteries need to adjust the positive and negative electrodes of the battery, such as using high nickel ternary positive electrode, silicon carbon negative electrode, and metal lithium anode. The possibility of low-cost solutions is very small, and in the entire development process of the battery, whether it is the development and use of new materials, or the improvement and experimentation of old solutions, it takes a lot of time and capital costs.
Do not treat solid-state batteries as an "explosive" innovative product, lithium batteries are not a one-step development to today's 600km endurance strength. We can divide the solid-state battery into three iterations:
The traditional electrolyte is replaced by a solid electrolyte + electrolyte to form a semi-solid state battery, and the positive and negative electrode materials are unchanged as the traditional lithium batteries;
The positive electrode still uses ternary materials or lithium iron phosphate, and the negative electrode uses lithium metal to improve the energy density of the battery, and it is still a semi-solid battery form to retain the electrolyte;
Find the safest and most efficient solution for solid-solid contact, remove the electrolyte, replace the negative electrode can be replaced with a higher specific energy silicon carbon anode, lithium metal anode.
Most of the solid-state batteries we are talking about and seeing now are in the initial stage of solid-state batteries, and semi-solid-state batteries will temporarily become the mainstream of the market before the real solid-state batteries are mass-produced.
Some car companies have released their own brand solid-state battery on the car schedule:
Ford and BMW will start using sulfide solid-state electrolyte batteries in 2022, and BMW may officially mass-produce in 2030 (which may be an ONE product invested above);
Volkswagen plans to use solid-state batteries in 2025 and build six battery factories in Europe by 2030;
Hyundai plans to launch solid-state battery products in 2030.
The reason why solid-state batteries are difficult is that the technical level is almost equivalent to starting from scratch, and the technical reserves of mass-produced batteries before are not related. For the market is not a solid-state battery, the market just needs a high mileage battery, do not care whether you are solid-state, semi-solid-state, or silicon-carbon anode battery, the ultimate purpose is to promote the development of battery technology to improve the cost performance and commercialization of 1000km battery life battery. Compared with solid-state batteries, silicon-carbon anode batteries have been industrialized in small batches earlier.
Why is it said that silicon carbon materials have been industrialized? For example, the GAC Aion AION LX PLUS 1000km version has a maximum endurance of 1000km, using a sponge silicon anode battery, replacing the traditional graphite element with silicon elements.
In addition, there are products/companies that we are more familiar with:
Starting in 2019, the anode of Tesla's Model S power battery is adulterated with silicon elements;
Tesla Model 3, adding 10% silicon to artificial graphite, the energy density of the monomer reaches 300Wh/kg;
In the Ningde era, the ratio of high nickel ternary + silicon carbon anode battery cell can reach 304Wh/kg.
Silicon is the second most abundant element in the earth's crust, and silicon-based materials have higher energy density, but its weakness and difficulty is that the volume will expand during charging and discharging. After the frequent charging and discharging of silicon elements, the volume repeatedly expands and contracts, which may lead to the accumulation of silicon from the inside and cause the silicon material to be chalked, and the final result is that the cycle performance becomes poor.
Therefore, if the silicon-based anode material wants to be commercialized and popularized, it must pass the modification research. For example, the Tesla silicon anode is the positive solution through the continuous adjustment of the silicon carbon ratio, when the silicon anode was developed to the Tesla Model 3, it was already a third-generation improved version, and has been incorporated with a high silicon content of 10%.
For the modification of silicon anode applications, the mainstream means are conductive material composite, nano, new binder, interface stability optimization and other means.
Conductive material composite, is now more common silicon carbon anode such a combination;
Silicon nano has higher capacity, more stable structure and performance, faster charging and discharging capacity, but the preparation method is complex and costly;
The binder can better pulverize the silicon particles and improve the circulation stability of the silicon anode material.
In the above-mentioned AION LX PLUS promotional materials, it is mentioned that the use of "sponge silicon anode sheet" batteries may replace the graphite /silicon composite anode provided by the original AVIC lithium battery, as for the use of the above-mentioned nano, new binder treatment methods, I am more inclined to use after all, to improve the cycle life of silicon element anode materials to meet market demand.
In fact, silicon elements / silicon in line with the material negative electrode has long been applied, the difference is the silicon element content of the matter, in order to ensure the need for recycling under the premise of the current 300Wh / kg energy density of the battery is basically used silicon carbon anode material. In the same way, like lithium batteries and solid-state batteries, they have to slowly and iteratively increase the proportion of silicon elements in the negative electrode.
summary
In terms of the market, what is needed is a cost-effective battery, solid/semi-solid and silicon element anode battery, who can commercialize it faster? Both types of batteries need to be slowly iteratively upgraded, and at present, silicon anode material batteries are "iterating" to continuously increase the proportion of silicon elements, and the first mass production product of solid-state batteries has not yet been officially installed.
No matter which of the above batteries is successfully commercialized, it is an innovation in battery technology, and now lithium-ion batteries have almost been pushed to the limit of performance, and can only be exchanged for high cruising range without increasing energy density. But the problem left for the new battery, in addition to the technological innovation, is also a big problem in cost control.