What is the main energy source for new battery materials after ten years?
Although the application scale of ternary materials, especially high-nickel cathode materials, is still far from the peak, now consider the future of ternary materials, early? Power battery is the foundation of the development of new energy vehicles in China. The ancients have a cloud: the first move is to move, the move will be. Take a look at the core arguments of this article:
The cobalt and nickel resources for power lithium batteries will be in short supply in 2030, and the development of ternary materials will be unsustainable;
The new cathode material in the future must be a high potential material superior to the current embedded cathode material;
The adaptation of silicon-based materials to new cathode materials not only increases their energy density, but also significantly reduces the cost of lithium-ion batteries.
Electric vehicles need power sources. The specific energy, life, safety and price of power batteries are crucial to the development of pure electric vehicles. Lithium-ion batteries have the advantages of high specific energy, low self-discharge and long life. Practical electric vehicle battery. After more than 20 years of scientific and technological progress, the performance of LIBs has been greatly improved. The specific energy density in lithium battery packs has increased nearly three times, from less than 200Wh/L to over 700Wh/L. The production cost is about 3% of the original, and the current production cost can be controlled below 150$/kWh. But this is still higher than the US$10 plan for the US Department of Energy. The power battery with a current power of 50-100KW.h weighs about 600 kg and the volume is about 500L.
Because the energy density of current lithium batteries is close to the theoretical maximum, the energy density increase of LIBs is gradually slowing down. The rapid growth of the battery market makes LIBs price cuts even more out of reach. Conversely, in the past two years, the surge in lithium battery production has almost quadrupled the price of cobalt from $22 to $81 per kilogram. Increased market demand and rapid price increases have encouraged some producers to cut corners and violate environmental and safety regulations. For example, in China, dust released from graphite mines has damaged crops, polluted villages and drinking water. In Africa, some miners exploit child labor, in the absence of protective equipment such as gas masks, and small mines that manually mine ore, usually do so in violation of the law. Some companies, including BMW, have strict policies in place to supervise their cobalt suppliers, while other electric vehicle manufacturers do not.
The easiest solution to this is to develop alternative types of electrodes that are cheaper than commonly used metals such as iron and copper. According to Professor Gleb Yushin of Georgia Institute of Technology in Atlanta, USA, and colleagues, the most promising "conversion-type cathode materials" are copper or iron fluoride or silicon. They store lithium chemically, but the technology is still in its early stages. To be practical, it is necessary to overcome stability, charging speed and manufacturing problems. Professor Gleb Yushin called on materials scientists, engineers and funding agencies to prioritize research and development of electrodes based on rich elements. Otherwise, the promotion of electric vehicles will be hit hard in ten years.
Nickel and cobalt are scarce and expensive
In current commercial batteries for electric vehicles, lithium ions are trapped in minute voids in the crystals constituting the electrodes (these are referred to as intercalated electrodes). The negative electrode is usually made of graphite and the positive electrode is made of metal oxide.
Common ternary cathode materials include nickel cobalt aluminum oxide (NCA, such as LiNi0.8Co0.15Al0.05O2) or nickel cobalt manganese oxide (NCM, such as LiNi0.6Co0.2Mn0.2O2 or LiNi0.8Co0.1Mn0.1O2) . A 100 kg lithium ion battery positive electrode material usually requires 6 to 12 kg of cobalt and 36 to 48 kg of nickel. While cobalt is often a by-product of copper and nickel mining, it also requires complex processes to separate from other metals. Most deposits contain only 0.003% cobalt metal, and few cobalt deposits are concentrated to the extent that they are worth mining. Thus, of the 1015 tons of cobalt stored on Earth, only 107 tons are available. Similarly, only 108 tons of the world's 1015 tons of nickel reserves have commercial exploitation value.
Cobalt-rich minerals are now found in only a few places. The African Congo (DRC) provided half (56%) of the world's 148,000 tons of cobalt in 2015. Most of them flow to China, and China has 200,000 to 400,000 tons of cobalt inventories. Australia has 14% of the world's cobalt reserves, which can be mined from the deep seabed. However, such mining costs, ecology and economy are too high to be fully exploited.
Similarly, the production of nickel is dominated by more than a dozen countries. In 2017, Indonesia, the Philippines, Canada, New Caledonia, Russia and Australia jointly supplied 72% of the world's 2.1 million tons of ore. But less than one-tenth of them are used in lithium batteries; the rest are mainly used in steel and electronics. Although nickel extraction costs are lower than cobalt, since 2015, demand growth has increased nickel prices from $9 per kilogram to $14, an increase of about 50%. Both cobalt and nickel experienced sudden price increases and collapses. For example, Australia's supply disruption, China's demand for steel increased, and the speculative behavior of hedge fund managers led to a five-fold increase in nickel prices, while in 2008-2009 cobalt prices tripled.
Cobalt and nickel are expected to be in short supply
If this continues, cobalt and nickel will have a supply gap within 20 years. As the demand for LIBs continues to increase, it is expected that cobalt will be in short supply by 2030, and nickel may be out of stock by 2037. Although we can mine poor quality ore, higher processing costs will push up the price of cobalt and nickel.
Electric manufacturers and the government expect to produce 10 to 20 million electric vehicles per year by 2025. If the battery of each car requires 10kg of cobalt, by 2025, only electric cars need 100,000-200,000 tons of cobalt per year, which is currently the majority of the world's production. Similarly, 400-800,000 tons of nickel is needed each year, which is equivalent to 20-40% of all metals today. When trucks, buses, airplanes, and ships use power batteries, more batteries are needed. By 2050, 500-800,000 tons of cobalt is required to produce 50 to 80 million electric vehicles per year. After 2030, this will far exceed the current mining capacity. Similarly, by 2050, the demand for nickel will increase by 2-3 times. By the middle of 2030, the shortage of nickel will be obvious, and recycling will not be able to supplement supply. Because the life of lithium-ion batteries is 15-20 years, it is three times that of lead-acid batteries in 5-7 years. Once the supply peaks, we estimate that the price of electric car batteries may rise by more than $1,000.
The way out of the future battery material geometry?
The answer is to use conventional metals (iron, copper) to produce lithium ion battery cathode materials. For example, iron is not only cheap (as low as 6 cents / kg) but also rich in reserves (76 billion tons). Since conventional iron-rich materials (LiFePO4) and manganese-rich materials (LiMnO2 or LiMn2O4) have various drawbacks in use, the most promising alternative is to use "replacement of cathode material" in the electrode. Copper/iron fluorides and silicon react chemically with lithium ions to achieve lithium storage and can hold up to six times more energy than standard positive electrodes.
The mechanism of the conversion type positive electrode material: its electrochemical conversion reaction is a novel lithium storage mechanism different from the conventional lithium ion insertion/extraction reaction. There are multiple electron transfer during the reaction, so the electrode materials based on the electrochemical conversion reaction mechanism have a very high theoretical specific capacity. Such electrode materials are mainly composed of oxides, sulfides or fluorides of transition metals. Among them, transition metal fluorides have higher working potentials due to their stronger ionic bonds, and are more suitable for the positive electrode of lithium ion batteries. material. Among them, silicon-based materials are very suitable for matching with them.
Once the two materials are successfully used, the battery that powers the electric car can be cut in half, while the cost, weight and volume will be reduced by half or more. But to achieve this goal, battery researchers need to develop high-performance fluoride materials and more efficient electrolytes. Engineers need to work hard to develop equipment and processes that use these materials. In addition, the battery prepared by the conversion type material has some disadvantages, such as low conductivity and poor rate performance; the side reaction of the conversion material and the electrolyte is serious; the positive and negative SEI films are formed thick and have voltage hysteresis; The expansion and contraction of the electrode after charging is more serious.
Introduction to replacement materials
Compared with the embedded material electrode, during the charging and discharging process, the breaking material and the Li bond may be broken and formed before and after the bonding. After Li enters FeF2, the Fe-F bond is broken, and Li and F are recombined to form LiF (Type A).