In recent years, new energy vehicles have received much attention. Compared with traditional gasoline vehicles, new energy vehicles have advantages such as being green and energy-saving. However, in people's minds, their performance still lags behind that of gasoline vehicles. In fact, with the continuous upgrading of new energy vehicle technology, especially with the continuous improvement of battery power, the performance of new energy vehicles has gradually caught up with that of gasoline vehicles.
For electric vehicles, an ideal battery should have: sufficient energy density to allow for a longer range; sufficient power density to enable the vehicle to accelerate quickly and climb hills; fast energy replenishment speed for rapid charging or battery swapping; and low cost, with a competitive combination of lifespan and price.
So, which type of battery is reliable and urgently needed for electric vehicles?
Corrosion-resistant aluminum-air batteries
According to industry insiders, aluminum-air batteries are almost comparable to gasoline, and they are lighter and cheaper than lithium-ion batteries, but they have one major problem—corrosion.
If lithium-ion batteries are not used for a month, they will lose 5% of their capacity, while aluminum-air batteries will lose 80% of their capacity due to the corrosion of aluminum.
According to recent foreign media reports, a research team published a paper in the journal *Science* claiming to have found a solution. Their aluminum-air battery loses only 0.02% of its capacity in a month, representing an improvement of over a thousand times.
How was this achieved? Researchers placed a thin film between the anode and cathode of the battery, which is filled with electrolyte when the battery is in use. Once the battery is in standby mode, the side closest to the aluminum is flushed with oil, which protects the aluminum. When the battery needs to be used again, the electrolyte replaces the oil. Because aluminum repels oil in water, no oil remains in the water.
In the test, the researchers simulated real-world applications by first using a small portion of the battery's charge, then letting it sit for a day or two, and then reusing it. The result was that the battery lasted for 24 days, eight times longer than previous aluminum-air batteries.
Does this mean that aluminum-air batteries will replace lithium batteries in the next few years?
“No,” replied Yang Weiqian, a researcher specializing in aluminum-air batteries. He explained that aluminum-air batteries still have many key issues to resolve. For example, power batteries require high power output, which is a weakness of aluminum-air batteries, particularly in acceleration and hill-climbing performance. Additionally, they have numerous load components, such as ventilation, heat dissipation, and electrolyte circulation systems. Placing these on a vehicle would place a significant burden on the battery. Therefore, they are generally best used as static batteries in base stations, serving as backups during extended driving range.
According to reports, Alcoa Canada and the Israeli company Phinergy have demonstrated the ability to store enough electricity for a 3,000-kilogram driving range using a 100-kilogram aluminum-air battery. Cars using this type of battery still require a lithium-ion battery; the aluminum-air battery only activates after the lithium-ion battery is depleted.
Zero-emission hydrogen fuel cells
We know that the combustion of hydrogen and oxygen produces water, achieving zero pollution. Moreover, as the first element in the periodic table, hydrogen is inexhaustible. This alone makes hydrogen fuel cells a highly desirable resource for many countries around the world.
Industry experts explain that compared to other batteries, the biggest advantage of hydrogen fuel cells is their extremely high energy density, reaching 3 kWh/kg in the laboratory, which is much higher than other types of batteries. When used in automobiles, this allows for smaller size and weight, providing longer driving range.
Taking the Hyundai NEXO as an example, it only takes 3-5 minutes to fully charge, greatly improving vehicle efficiency. More importantly, in terms of range, hydrogen fuel cell vehicles generally achieve a range of 500km+, while the Hyundai NEXO reaches 609km, even surpassing some comparable traditional gasoline vehicles.
Moreover, fuel cells have a cost advantage. Take the Toyota Mirai as an example; it uses "electrolyte membrane" fuel cell technology, which uses charge transfer during the chemical reaction of hydrogen and oxygen to generate electricity. Apart from using platinum as a catalyst, there are no consumables, and platinum itself is not consumed.
Nothing is perfect, and hydrogen fuel cells also have unresolved issues. Experts point out that the first is the price. The core components of hydrogen fuel cells are proton exchange membranes and platinum catalysts, which are very expensive materials, making it difficult for hydrogen fuel cells to become widespread. The second is the source and storage of fuel. Hydrogen fuel cells require hydrogen, but the production, transportation, storage, and refueling of hydrogen itself are extremely inconvenient, costly, and dangerous, and the technology is not yet mature.
Tesla CEO Elon Musk once stated, "Even if we theoretically achieve the best performance of a fuel cell, it still cannot compete with today's lithium-ion batteries." Clearly, hydrogen fuel cells still have a long way to go before they can be applied in practice.
Practical lithium batteries
Which type of battery is practical at present?
"Of course, it's lithium-ion batteries," Dr. He Yanbing, associate researcher at the Department of Energy and Environment, Tsinghua University Shenzhen Graduate School, replied in an interview.
It is reported that although there are many types of power batteries used in electric vehicles, from the perspective of practical application at present, most manufacturers in the world have chosen lithium batteries. There are two main types of batteries: lithium-ion batteries for high-speed electric vehicles, including lithium iron phosphate, lithium manganese oxide, and ternary lithium batteries, and lead-acid batteries for low-speed electric vehicles.
Tesla uses Panasonic ternary lithium batteries, which offer a good balance of energy density, power density, and safety, making them a moderate choice. Safety issues during charging and discharging are addressed through software. However, in the event of an extreme collision, the powerful impact could breach the battery pack's protection, causing the car to still catch fire and explode. The only advantage is that the robust protection provides the occupants with time to escape.
Lithium iron phosphate (LFP), also known as BYD's iron battery, is widely used. Its advantages include relatively good safety; although accidents do occur, it is considered the best in comparison. It has good power density, allowing for high-rate discharge and decent acceleration performance. It also has advantages in cycle life, resulting in relatively low long-term operating costs. The disadvantages are relatively lower energy density, meaning it doesn't offer a competitive driving range for the same weight. Furthermore, its low-temperature performance is poor, with significant power loss in cold weather.
Lithium manganese oxide batteries are widely used by Japanese companies. Their advantages include better low-temperature performance, less power loss at low temperatures compared to lithium iron phosphate batteries, and lower price. While their safety is not as good as lithium iron phosphate batteries, it's still quite good. However, the material itself is not very stable and is prone to gas generation.
He Yanbing emphasized that current battery research and development should not be a leap forward in blindly pursuing energy density. Some manufacturers have made the separators extremely thin and used very few auxiliary materials, which can lead to instability in the battery system and create safety hazards. Energy density should be increased while improving the safety and stability of the battery.
In conclusion, industry insiders say that the future trend of electric vehicles is to use pure batteries or hydrogen power, but the charging speed of large-capacity batteries is still a bottleneck, and widespread adoption will take time.
The current solution is a hybrid approach, combining gasoline and electricity as energy sources. In the coming years, as lithium battery prices further decrease and capacity increases, electric vehicles and plug-in hybrid vehicles will become increasingly cheaper and perform better. Let's wait and see.
