First, the materials are different. Power battery plates are mostly made of lead-calcium alloy, while starting batteries are mostly made of lead-antimony alloy.
Second, the discharge times differ. A power battery can discharge with a small current for several hours, achieving a deep discharge depth. A starter battery, on the other hand, has a very short discharge time.
However, it operates with a very large discharge current, several hundred amperes.
Third, the electrolyte concentration differs. To achieve a longer driving range, many people increase the electrolyte concentration of power batteries to 1.31. However, this makes the battery very prone to sulfation, causing the plates to lose their activity. The standard electrolyte concentration for starting batteries is 1.28. At this concentration, a larger discharge current can be obtained, making the car easier to start.
First, the materials are different. Power battery plates are mostly made of lead-calcium alloy, while starting batteries are mostly made of lead-antimony alloy.
Second, the discharge times differ. A power battery can discharge with a small current for several hours, achieving a deep discharge depth. A starter battery, on the other hand, has a very short discharge time.
I. Different in nature
When all batteries are new, the capacity of a power battery is tested with a discharge tester. The capacity of a power battery is generally around 1000-1500mAh, while the capacity of a regular battery is over 2000mAh, and some can reach 3400mAh.
III. Different discharge power
A 4200mAh power battery can be completely discharged in just a few minutes, something a regular battery simply cannot do. Therefore, the discharge capacity of a regular battery is incomparable to that of a power battery. The biggest difference between power batteries and regular batteries lies in their higher discharge power and higher energy density. Because power batteries are primarily used for vehicle power supply, they require a significantly higher discharge power compared to regular batteries.
IV. Different Applications
Batteries that provide driving power for electric vehicles are called power batteries, including traditional lead-acid batteries, nickel-metal hydride batteries, and emerging lithium-ion power batteries. They are divided into power batteries (hybrid electric vehicles) and energy batteries (pure electric vehicles). Lithium batteries used in consumer electronics products such as mobile phones and laptops are generally referred to as lithium batteries, to distinguish them from the power batteries used in electric vehicles.
The main types of power batteries
Currently, the mainstream technologies in the market are still lead-acid battery technology, nickel-metal hydride battery technology, fuel cell technology, and lithium battery technology.
lead-acid batteries
Lead-acid batteries have the longest history of application and the most mature technology. They are the lowest cost and selling price batteries and have achieved mass production. Among them, valve-regulated sealed lead-acid batteries (VRLA) were once an important power battery for vehicles, used in many EVs and HEVs developed by European and American automakers, such as the Saturn and EVI electric vehicles developed by General Motors in the 1980s and 1990s, respectively.
However, lead-acid batteries have low specific energy, short driving time, high self-discharge rate, and low cycle life; their main raw material, lead, is heavy, and the production and recycling processes may generate heavy metal pollution. Therefore, lead-acid batteries are currently mainly used in ignition devices for starting cars, as well as in small devices such as electric bicycles.
Nickel-metal hydride batteries
Nickel-metal hydride (Ni/MH) batteries exhibit excellent resistance to overcharge and over-discharge, do not suffer from heavy metal contamination, and do not experience electrolyte fluctuations during operation, allowing for a sealed design and maintenance-free operation. Compared to lead-acid and nickel-cadmium batteries, Ni/MH batteries offer higher specific energy, higher specific power, and longer cycle life.
Its disadvantages include a poor memory effect, and the gradual loss of catalytic ability of the hydrogen storage alloy as charge-discharge cycles continue, leading to a gradual increase in internal battery pressure and affecting battery performance. Furthermore, the high price of nickel metal also contributes to the high cost.
In terms of key materials, nickel-metal hydride (NiMH) batteries mainly consist of a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode is a nickel electrode (Ni(OH)2); the negative electrode generally uses a metal hydride (MH); and the electrolyte is mainly liquid, with potassium hydroxide (KOH) as its main component. Currently, the research focus of NiMH batteries is primarily on the positive and negative electrode materials, and their technological development is relatively mature.
Nickel-metal hydride (NiMH) batteries for automobiles have achieved mass production and use, and are the most widely used type of onboard battery in the development of hybrid vehicles. The most typical example is the Toyota Prius, which currently has the largest mass production of hybrid vehicles. PEVE, a joint venture between Toyota and Panasonic, is currently the world's largest manufacturer of NiMH batteries.
Nickel-metal hydride (NiMH) batteries have now been phased out of the mainstream power battery market, so why does Toyota stubbornly stick to the NiMH battery camp?
This brings us to the biggest advantage of nickel-metal hydride batteries: their exceptional durability!
Consumer Reports, a well-known American automotive media outlet, once conducted a comparative test on a first-generation Prius after ten years of use. The test results showed that after 10 years and 330,000 kilometers, the first-generation Prius, equipped with a nickel-metal hydride battery, maintained the same level of fuel efficiency and power performance as when it was new, indicating that the hybrid system and nickel-metal hydride battery pack were still functioning properly.
Furthermore, even after ten years and 330,000 kilometers, the nickel-metal hydride battery pack in this first-generation Prius has never had any problems. The concerns raised a decade ago about battery capacity degradation significantly impacting fuel consumption and performance have not materialized. This suggests that the traditionally meticulous and conservative Japanese have indeed found unique reasons for their fondness for nickel-metal hydride batteries.
fuel cells
A fuel cell is a power generation device that directly converts the chemical energy present in fuel and oxidant into electrical energy. Fuel and air are fed into the fuel cell, and electricity is produced. Externally, it has positive and negative electrodes and an electrolyte, resembling a battery, but in reality, it cannot "store electricity" but is a "power plant".
Compared to conventional chemical batteries, fuel cells can be refueled, typically with hydrogen. Some fuel cells can use methane and gasoline as fuel, but these are usually limited to industrial applications such as power plants and forklifts. The basic principle of a hydrogen fuel cell is the reverse reaction of water electrolysis. Hydrogen and oxygen are supplied to the anode and cathode, respectively. Hydrogen diffuses outward through the anode and reacts with the electrolyte, releasing electrons that travel through an external load to the cathode.
The working principle of a hydrogen fuel cell is as follows: Hydrogen gas is delivered to the anode plate (negative electrode) of the fuel cell. Under the action of a catalyst (platinum), an electron is separated from the hydrogen atom. The hydrogen ion (proton) that loses the electron passes through the proton exchange membrane and reaches the cathode plate (positive electrode) of the fuel cell. However, electrons cannot pass through the proton exchange membrane. This electron can only reach the cathode plate of the fuel cell through the external circuit, thereby generating current in the external circuit.
After electrons reach the cathode plate, they recombine with oxygen atoms and hydrogen ions to form water. Since the oxygen supplied to the cathode plate can be obtained from the air, as long as hydrogen is continuously supplied to the anode plate, air is supplied to the cathode plate, and water vapor is carried away in a timely manner, electrical energy can be continuously provided.
The electricity generated by the fuel cell is used by an inverter, controller, and other devices to power an electric motor, which in turn drives the wheels through the transmission system and drive axle, enabling the vehicle to move on the road. Compared with traditional cars, fuel cell vehicles have an energy conversion efficiency of 60-80%, which is 2-3 times that of internal combustion engines.
Fuel cells use hydrogen and oxygen as fuel, and produce clean water as a byproduct. They do not produce carbon monoxide or carbon dioxide, nor do they emit sulfur or particulate matter. Therefore, hydrogen fuel cell vehicles are truly zero-emission, zero-pollution vehicles; hydrogen fuel is the perfect energy source for automobiles!
