On February 14, 2024, 24M Technologies, an American start-up, launched an electrolyte called EternalyteTM, which is designed for lithium metal batteries and aims to improve the cycle life and charge-discharge power of the battery, with a capacity retention rate of more than 83% for 500 cycles and a fast charge rate of 4C. In addition, in combination with the previously released ImperViotm separator technology, it prevents the growth of metal dendrites and improves safety by providing early warning of such failure modes.
By integrating the pole pieces directly into the battery system through ETOPTM technology, 24M's CEO and President Naoki OTA claims to be able to achieve a cost-effective and safe 1,000-mile-per-charge battery pack.
So, what is the origin of 24m? Are the technologies claimed above reliable? Can it successfully help electric vehicles achieve a range of 1,600 kilometers and say goodbye to range anxiety completely? This article takes you through the first thing.
1. Analysis of 24m battery technology
Judging from the information published by 24M, this battery with a range of 1600km is a lithium metal battery, and the energy density of the battery cell is 391Wh kg, which is not particularly high in the field of lithium metal (considering that Lishen has launched a 402Wh kg high-silicon semi-solid-state battery at the end of January, and a 402Wh Kg semi-solid-state battery has been developed with reference to Lishen Battery).
However, the battery has a system energy density of up to 350 Wh kg (mass group efficiency of nearly 90%), which is more than 37% higher than the current 255Wh kg claimed by Kirin batteries. The energy density of the Kirin battery system used in ZEEKR 009 is only 200 205wh kg, and the total energy of 140kWh can achieve a range of more than 1000km (refer to the analysis of the first high-energy battery cell of Kirin battery).
The energy density of the system at 350Wh kg is 1 more than that at 200Wh Kg75 times, assuming that the weight of the battery pack remains the same, then the total energy can be increased to 140*175=245kwh。According to the power consumption of 15 16kWh per 100 km, it can indeed achieve a range of more than 1600km (1000 miles).
In addition to high energy density, this lithium metal battery also supports a charge and discharge rate of 4C, and it is achieved under a load of 5mAh cm2, which is a huge improvement compared to the traditional lithium metal battery, which is an exponential improvement (the charge rate of the general lithium metal battery is 0.).5c or less).
As early as 2021, Professor Yet-Ming Chiang, the founder and chief scientist of 24M, published an article on Nature Energy to improve the critical current density of lithium metal batteries by compounding with liquid alkali metal (Na-K), in 3An ultra-high current density of 2mA cm2 is achieved under a load of 8 mA cm2. The current density of up to 20 mA cm2 is expected to be the best result of a combination of various strategies such as liquid alkali metal and electrolyte optimization.
However, it should be noted that the areal capacity of the NCM material for the cathode of this battery is only 3mAh cm2, and according to the capacity of 200mAh g of high-nickel material and the areal density of 20mg cm2, the areal capacity can easily reach more than 4mAh cm2.
With such a low areal capacity, a very high proportion of cathode material is required to achieve 391 Wh kg, which is expected to be more than 60%, which requires the legendary thick electrode technology, which is also based on the 24m foothold, officially known as Semi SolidTM.
Essentially an ultra-thick electrode, increasing the thickness of the conventional electrode by a factor of 50 to 300 500 m can greatly increase the mass proportion of the active substance and reduce the use of inactive material. At the same time, due to the use of ultra-thick electrodes, the capacity of a single electrode can be very high, which reduces the number of layers in parallel, and also creates conditions for the battery system to be directly grouped from the electrode piece. According to official data, the 24M ETOPTM (Electrode to Pack) can achieve 90% mass grouping efficiency, which can be described as a ceiling-level existence.
Due to the application of thick pole pieces, the separator of 24m semi-solid-state batteries can also become thicker, even similar to lead-acid batteries, such separators are not only safer (impervious means not easy to damage), but can also suppress short circuits caused by metal dendrites (the picture below is the 24m company tested its separator for stainless steel and lithium metal dendrites inhibition).
In addition, further innovations can be made on the separator, such as detecting the growth of lithium metal dendrites by coating a layer of conductive substance, which serves as an early warning. This technology was first published in 2014 by Professor Cui Yi of Stanford University (refer to Nature Comm, 2014, 5, 5193), from the 24m public product**, it can also be seen that its exposed external tabs are more than 4, and it is likely to add an output pole at the diaphragm to detect signals such as voltage, so as to predict the growth of dendrite in advance.
2. The development history and prospect analysis of 24M
24M was founded in 2010 by Professor Yeming Jiang, chief scientist of the Massachusetts Institute of Technology, and others. It is worth mentioning that Mr. Jiang is also one of the founders of A123, and has made outstanding achievements in improving the performance of lithium iron phosphate rate.
As early as around 2002, he published an article in the journal Nature, using ** metal ions such as NB, W, TI, MG, ZR, etc. to replace the Li position to greatly improve the electronic conductivity and rate performance of LFP (Nature Material, electronically conductive phospho-olivines as lithium storage electrodes). This was followed in 2003 by the establishment of A123.
He is very familiar with the material system and manufacturing technology of lithium-ion batteries, and knows that the proportion of inactive substances in the current battery system is too high, which is not conducive to the exertion of energy density and subsequent development. Moreover, the investment and energy consumption of fixed equipment in the manufacturing process are large and the cost is high. Therefore, 24M was established to innovate the production process of lithium batteries, eliminating the steps such as baking, and significantly reducing equipment investment and manufacturing costs.
Dubbed and trademarked this innovative technology as SemiSolidTM, the heart of this semi-solid-state battery is the electrode design, eliminating the traditional binders and solvents such as NMP, and mixing the active material, conductive carbon and electrolyte directly together and coating the electrode piece. Since there is no binder, the mixed material has a certain degree of fluidity, just like clay and thin mud, and is a state of solid-liquid mixture, so it is called semi-solid.
**The next generation of batteries has been sorted out with reference to the official public information of 24M (for details, please refer to some data of 1000 weeks and 13000 weeks - 24M semi-solid-state batteries (high nickel graphite, iron-lithium graphite system)), due to the use of thick electrodes, in addition to the cancellation of binders and NMP, copper foil and aluminum foil save more than 60% compared with traditional lithium batteries, save 80% of separators, and save electrolytes and tabs to varying degrees.
Moreover, in the manufacturing process, the 15 steps in the front and middle of the current lithium battery are directly shortened to 5 steps, that is, mixing, coating, lamination, welding, and shelling (soft pack or aluminum shell), because all the baking processes and electrolyte leachate are omitted, the time is also shortened from the original 22h to 1h.
Since its inception, 24M has not launched products on a large scale, but has used technology transfer and licensing to cooperate with a number of companies (see the 1,600 km range of semi-solid-state batteries is coming), including Volkswagen, Fujifilm, Lucas TVS, Axxiva and Freyr. This is the same as that of Taiwan's semi-solid-state battery manufacturer Huineng Technology (for details, please refer to Huineng solid-state battery is a new species?). It can focus on technology, light assets and avoid competition with other battery companies.
Among them, in 2020, 24M announced that it had reached a cooperation with Japan's Kyocera Group, and Kyocera will develop its residential energy storage system Enerezza using semi-solid lithium batteries produced by the Semisolid electrode manufacturing process of 24M technology.
In 2021, 24M signed a licensing agreement with Norwegian battery start-up Freyr, granting Freyr the rights to produce lithium batteries based on 24M's current and all future technologies.
At the beginning of 2022, Volkswagen acquired a 25% stake in 24m, and the two parties officially became strategic partners. The Volkswagen Group plans to establish a wholly owned subsidiary, together with 24M, to "develop a technology for the production of semi-solid-state batteries for automobiles."
It is worth mentioning that the domestic Anhui Anwa New Energy Technology *** The company seems to be related to Chery and Guoxuan, a bit unknown), its semi-solid-state solid-state battery technology is also from 24m, announced at the end of 2022 to build a factory in Yantai, Shangshan, mainly producing semi-solid-state technology systems with an energy density of 300-340wh kg power batteries and energy storage batteries, which are used in vehicles, energy storage, battery swapping and other market fields.
Summary:The 24m semi-solid-state battery is a semi-solid in the physical sense, which directly mixes the active material, conductive agent and electrolyte, eliminating the baking step of binder and traditional pole piece, reducing the manufacturing step, saving equipment investment and manufacturing cost. Although the name is the same, this is a completely different technical solution from the semi-solid-state battery in the chemical sense that is currently the main promotion in the industry. It is worth mentioning that 24M has also applied for its own SemisolidTM trademark, which is a real enterprise that promotes semi-solid.
Although the 24M's newly released lithium-metal battery system has an energy density of up to 350Wh kg and is also expected to achieve an ultra-long range of 1600km, the current application field is not clear. At present, the LFP battery on the electric vehicle can achieve a range of 700km, and the ternary battery can achieve a range of 1000km. For the field of electric aircraft with higher energy requirements, the power requirements are equally important, and the power performance of thick electrode technology is generally poor, resulting in a low discharge rate, and whether it can be applied in the field of electric aircraft is also a problem.
In any case, the 24m semi-solid-state battery technology is at least a major attempt to innovate in the field of manufacturing, and it is worth learning from. Professor Jiang is also one of the most prominent Chinese in the field of academic attainment and industrialization, and has co-founded 7 start-up companies, including battery company A123 Systems, 24M, Form Energy, Desktop Metal, American Superconductor, and Sublime Systems. It is hoped that the 24m semi-solid-state battery technology will bear fruit in the right field.