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Power batteries exhibit different characteristics due to variations in specifications, materials, and design technologies. Currently, the four major power batteries in China are lithium-ion batteries, hydrogen fuel cells, supercapacitors, and aluminum-air batteries. Among these, lithium-ion batteries, supercapacitors, and hydrogen fuel cells have been widely applied and commercialized, while aluminum-air batteries are still in the experimental stage. The four major power batteries differ in materials and methods of obtaining electrical energy. For instance, lithium batteries and supercapacitors require external charging to obtain energy, while hydrogen fuel cells need external hydrogen gas, and aluminum-air batteries require external aluminum plates and electrolytes. Below, SHINHOP Laser will help you understand the characteristics of each.

1. Characteristics of Hydrogen Fuel Cells
1. Good environmental compatibility
Hydrogen fuel cells provide efficient and clean energy. The water they emit is not only minimal but also very clean, thus there is no water pollution issue. Additionally, since fuel cells do not need to convert thermal energy into mechanical energy like engines do, but instead directly convert chemical energy into electrical and thermal energy, their energy conversion efficiency is high and noise is low.
2. Good operational performance
Hydrogen fuel cells generate electricity without the need for complex and large configurations. The battery stack can be modularly assembled. For example, a 4.5MW power generation unit can consist of 460 battery components, occupying much less land than a thermal power plant. Hydrogen fuel cells are suitable as decentralized power generation devices. Moreover, compared to thermal, hydro, and nuclear power generation, the construction cycle of hydrogen fuel cell power plants is short, and expansion is easy, allowing for phased construction based entirely on actual needs. At the same time, hydrogen fuel cells have high operational quality and excellent characteristics in responding to rapid load changes (such as peak loads), being able to switch from low power to rated power within seconds.
3. High output performance
When working, hydrogen fuel cells convert the stored energy of the fuel into electricity and heat, with an efficiency of over 40% for converting electrical energy, while turbines can only convert 1/3 into electricity.
4. Flexible structural characteristics
Hydrogen fuel cells are very flexible in assembly, making it easy to adjust power levels. Compared to traditional engines, due to the good modularity of hydrogen fuel cells, output power and voltage can be easily adjusted by increasing or decreasing the number of individual cells without increasing infrastructure investment. Therefore, they are also easy to construct and can be easily integrated into grid control. This characteristic of fuel cells enhances system stability.
5. Abundant sources of hydrogen
Hydrogen, as a secondary energy source, can be obtained through various methods, such as hydrogen production from coal, natural gas reforming, and water electrolysis. When fossil fuels are depleted, hydrogen will become the main fuel and energy source in the world. Moreover, using solar energy for water electrolysis to produce hydrogen results in no carbon emissions during the process, making hydrogen a potential ultimate energy source.
6. Existing bottlenecks
From the current development perspective, the popularization of hydrogen fuel cells faces certain bottlenecks, such as the high cost of the batteries themselves and the lack of widespread infrastructure.

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2. Characteristics of Lithium-ion Batteries
1. Voltage platform
Due to the different positive and negative electrode materials used, the working voltage range of lithium-ion battery cells is 3.7~4V. Among them, the widely used lithium iron phosphate battery has a working voltage of 3.2V, which is 3 times that of nickel-hydrogen batteries and 2 times that of lead-acid batteries.
2. High specific energy
Currently, the energy density of lithium-ion power batteries for passenger vehicles is close to 200Wh/kg, and it is expected to reach 300Wh/kg by 2020.
3. Short battery life
Due to the limitations of electrochemical material characteristics, the cycle life of lithium-ion batteries has not achieved breakthroughs. For lithium iron phosphate, the cycle life of a single cell can exceed 2000 cycles, but only over 1000 cycles when grouped. This does not meet the requirement for public transport operation over 8 years.
4. Greater environmental impact
Lithium-ion batteries use lightweight lithium metal. Although they do not contain harmful heavy metals like mercury and lead, they are considered green batteries with minimal environmental pollution. However, due to the presence of metals like nickel and manganese in their positive and negative electrode materials and electrolytes, lithium-ion batteries have been classified in the U.S. as batteries containing toxic and harmful substances, including flammable, leachable toxic, corrosive, and reactive materials. They currently contain the most toxic substances among all types of batteries, and the complex recycling process leads to high costs, resulting in a low recycling rate. Therefore, discarded batteries have a significant environmental impact.
5. Still high costs
The initial purchase cost of lithium-ion batteries is high. Taking the mainstream lithium iron phosphate battery used in public transport as an example, the price is about 2500 RMB/kWh. With the popularization of electric vehicles, it is expected to drop below 1000 RMB/kWh by 2020. Due to the limitations of cycle life after grouping, public transport vehicles typically need to replace batteries every three years, which puts significant cost pressure on operating units.
6. Significant impact on the power grid
Firstly, the large-scale application of pure electric vehicles will highlight the harmonic interference of charging equipment on the power grid due to high charging demands, affecting the power supply quality of the grid. Secondly, during fast charging, due to high charging rates, the charging power is relatively high (50kW for passenger cars, around 150~250kW for buses), which imposes a significant load impact on the power grid.
Therefore, based on the current technology level of lithium-ion batteries, their application in electric vehicles is mainly in short-range pure electric vehicles with a driving range of less than 200km.
3. Characteristics of Supercapacitors
1. Extremely high charge and discharge rates
Supercapacitors have a high power density and can release hundreds to thousands of amperes of current in a short time. They charge quickly, completing the charging process in tens of seconds to a few minutes. Supercapacitor buses and trams utilize this feature to charge in a short time and drive the vehicles forward.
2. Long cycle life
The charge and discharge process of supercapacitors has minimal loss, so theoretically, their cycle life is infinite, practically reaching over 100,000 times, which is 10-100 times higher than that of batteries.
3. Good low-temperature performance
The charge transfer that occurs during the charge and discharge process of supercapacitors mostly takes place on the surface of the active material of the electrodes, so the capacity decreases very little with temperature. In contrast, lithium-ion batteries can experience a capacity reduction of up to 70% at low temperatures.
4. Energy density is too low
One of the bottlenecks in the application of supercapacitors is that the energy density is too low, only about 1/20 of that of lithium-ion batteries, approximately 10Wh/kg. Therefore, they cannot serve as the main power source for electric vehicles and are mostly used as auxiliary power sources, primarily for quick start devices and regenerative braking systems.
IV. Characteristics of Aluminum-Air Batteries
1. Low material cost, high energy density
The active material of the negative electrode of aluminum-air batteries is abundant metallic aluminum, which is inexpensive and environmentally friendly. The active material of the positive electrode is oxygen from the air, and the capacity of the positive electrode can be considered infinite. Therefore, aluminum-air batteries have advantages such as being lightweight, compact, and having a long lifespan.
2. Key technologies have not achieved breakthroughs and have not yet left the laboratory
Issues such as air electrode polarization and aluminum hydroxide precipitation are significant obstacles affecting the commercialization of metal-air batteries, and there are considerable bottlenecks in improving the performance of aluminum-air batteries. They are currently still in the laboratory stage, and there is still a considerable distance to commercialization.
Difficulties in manufacturing lithium-ion power batteries:
Since power batteries are generally square aluminum shell batteries, there is no industry standard for their specifications and sizes, leading to many types of products in the market. There are significant issues in production quality assurance, maintenance, and application. Manufacturers often need to customize numerous production equipment to provide production efficiency, such as laser welding equipment and laser welding assembly lines. One of the major issues in welding is the sealing of the cover plate, which is one of the most frequently problematic technologies in power battery welding. A wealth of laser welding experience and a mature and stable welding system are required to ensure successful welding. SHINHOP Laser has unique insights into the process characteristics, advantages, and disadvantages of power batteries, especially with rich experience in applying laser welding technology in power battery manufacturing. If you want to excel in power battery user experience, consider visiting the SHINHOP Laser factory for on-site inspection to jointly address the difficulties in power battery welding manufacturing.