With the continuous development of new energy vehicles, power batteries are receiving increasing attention. Batteries, motors, and electronic control systems are the three key components of new energy vehicles, with the power battery being the most crucial—essentially the "heart" of the vehicle. So, what are the main categories of power batteries for new energy vehicles?
1. Lead-acid batteries
Lead-acid batteries (VRLA) are rechargeable batteries whose electrodes are primarily made of lead and its oxides, and whose electrolyte is sulfuric acid solution. When charged, the positive electrode of a VRLA battery is mainly composed of lead dioxide, and the negative electrode is mainly composed of lead; when discharged, both the positive and negative electrodes are mainly composed of lead sulfate. A single VRLA cell has a nominal voltage of 2.0V, can discharge to 1.5V, and can be charged to 2.4V. In practice, six VRLA cells are often connected in series to form a 12V VRLA battery; other voltage ratings include 24V, 36V, and 48V.
Lead-acid batteries, as a relatively mature technology, remain the only battery suitable for mass production of electric vehicles due to their low cost and high discharge rate. However, lead-acid batteries have very low specific energy, specific power, and energy density, making it impossible for electric vehicles powered by them to achieve good speed and driving range.
2. Nickel-cadmium batteries and nickel-metal hydride batteries
Nickel-cadmium batteries (NiCd, pronounced "nye-cad") are a popular type of rechargeable battery. These batteries use nickel hydroxide (NiOH) and metallic cadmium (Cd) as the chemicals that generate electricity. While they perform better than lead-acid batteries, they contain heavy metals and can cause environmental pollution when used or disposed of.
Nickel-cadmium (NiCd) batteries can be recharged and discharged more than 500 times, making them economical and durable. They have low internal resistance, allowing for rapid charging and providing a large current to the load. Furthermore, their voltage change during discharge is minimal, making them an ideal battery for DC power supply. Compared to other types of batteries, NiCd batteries are more resistant to overcharging and over-discharging.
Nickel-metal hydride (NiMH) batteries are synthesized from hydrogen ions and metallic nickel. They have 30% more energy storage than nickel-cadmium (NiCd) batteries, are lighter, have a longer lifespan, and are environmentally friendly, but they are much more expensive.
3. Lithium batteries
Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloys as the negative electrode material and a non-aqueous electrolyte solution. Lithium-ion batteries can be broadly classified into two categories: lithium metal batteries and lithium-ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable.
Lithium metal batteries typically use manganese dioxide as the positive electrode material, metallic lithium or its alloys as the negative electrode material, and a non-aqueous electrolyte solution. The main components of a lithium battery include: positive electrode material, negative electrode material, separator, and electrolyte.
Among cathode materials, the most commonly used materials are lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials (polymers of nickel, cobalt, and manganese). Cathode materials account for a large proportion (the mass ratio of positive to negative electrode materials is 3:1 to 4:1), because the performance of cathode materials directly affects the performance of lithium-ion batteries, and their cost directly determines the cost of the battery.
Currently, anode materials are mainly composed of natural graphite and artificial graphite. Anode materials under investigation include nitrides, PAS, tin-based oxides, tin alloys, nanomaterials, and other intermetallic compounds. As one of the four main components of lithium-ion batteries, anode materials play a crucial role in improving battery capacity and cycle performance, and are a core link in the midstream of the lithium-ion battery industry.
4. Fuel Cell
A fuel cell is a non-combustion electrochemical energy conversion device. It continuously converts the chemical energy of hydrogen (or other fuels) and oxygen into electrical energy. Its working principle is that H2 is oxidized into H+ and e- at the anode in the presence of a catalyst. The H+ passes through the proton exchange membrane to the positive electrode, where it reacts with O2 at the cathode to produce water. The e- passes through an external circuit to the cathode, and this continuous reaction generates an electric current. Although fuel cells contain the word "battery," they are not energy storage devices in the traditional sense, but rather power generation devices. This is the biggest difference between fuel cells and traditional batteries.
