Power battery is the key technology of electric vehicles, which determines its driving range and cost.
(1) Power batteries required for pure electric vehicles
The functional indicators and economic indicators that power batteries used for electric vehicles should include: (1) safety; (2) specific energy; (3) specific power; (4) life; (5) cycle price; (6) energy conversion efficiency. These factors directly determine the usability and economy of electric vehicles.
(2)Supercapacitor
The advantages of supercapacitors are high mass specific power and long cycle life. Their weaknesses are low mass specific energy and high purchase price. However, the cycle life is as long as 500,000 to 1 million times, so the price per cycle is not high. Compared with lead-acid batteries and Energy-type lithium-ion batteries connected in parallel can form a power supply system with excellent performance.
(3)Lead-acid battery
Lead-acid battery production technology is mature, safe and cheap, and waste batteries are easy to recycle. In recent years, through new technologies, shortcomings such as low specific energy, short cycle life, acid mist during charging, and possible lead pollution in the environment during production are being continuously overcome. Various indicators have been greatly improved, which not only enables better It is used as a power source for electric bicycles and electric motorcycles, and also plays a good role in electric vehicles.
(4) Lithium-ion batteries using lithium iron phosphate as the positive electrode
Lithium batteries with carbon as the negative electrode and lithium iron phosphate as the positive electrode have good overall performance: they are safer, do not use expensive raw materials, do not contain harmful elements, have a cycle life of up to 2,000 times, and have overcome the shortcomings of low conductivity. The mass specific energy of the energy battery can reach 120Wh/kg, and when used in parallel with a supercapacitor, it can form a power source with comprehensive performance. The mass specific energy of the power type is also 70~80Wh/kg, which can be used alone without the need to connect supercapacitors in parallel.
(5) Lithium-ion batteries using lithium titanate as the negative electrode
The volume of lithium titanate changes very little during charging and discharging, ensuring the stability of the motor mechanism and the long life of the battery; the lithium titanate electrode point is higher (1.5V relative to the Li+/Li electrode), and no generation is required when the battery is being charged. Lithium crystal dendrites ensure the high safety of the battery. However, due to the high potential of lithium titanate electrode, even if it is paired with the lithium manganate positive electrode with higher electrode potential, the voltage of the battery is only about 2.2V, so the specific energy of the battery is only about 50 to 60Wh/kg. Even so, the outstanding advantages of this kind of battery are high safety and long life, which are unmatched by other batteries.