The power source of new energy vehicles is generally based on power batteries. A power battery is actually a power source that provides a source of power for transportation vehicles. The main differences between it and ordinary batteries are:

First, the nature is different

Power batteries are batteries that power vehicles, generally as opposed to small batteries that power portable electronic devices; The common battery is a lithium metal or lithium alloy as the anode material, the use of non-aqueous electrolyte solution of the primary battery, and rechargeable battery lithium ion and lithium ion polymer battery is different.

Two, different battery capacity

In the case of new batteries, the discharge instrument is used to test the battery capacity, the general power battery capacity is about 1000-1500mAh; The capacity of the ordinary battery is more than 2000mAh, and some can reach 3400mAh.

Three, discharge power is different

A 4200mAh power battery can be in just a few minutes to emit electricity, but ordinary batteries can not do, so the discharge capacity of ordinary batteries can not be compared with the power battery. The biggest difference between power battery and ordinary battery is that the discharge power is large and the specific energy is high. Since the power battery is mainly used for vehicle energy supply, it has a higher discharge power than the ordinary battery.

Four, different applications

The 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, which are divided into power type power batteries (hybrid electric vehicles) and energy type power batteries (pure electric vehicles); Lithium batteries used in consumer electronics such as mobile phones and laptops are generally referred to as lithium batteries to distinguish them from power batteries used in electric cars.

Power battery existing main types

At present, the mainstream technology in the market is still lead-acid battery technology, nickel metal hydride battery technology, fuel cell technology, lithium battery technology.

Lead-acid battery

Lead-acid battery has the longest application history, the most mature technology, is the cost, the lowest price of the battery, has realized mass production. VRLA (VRLA) once became an important vehicle power battery, which was used in EV and HEV developed by many European and American automobile companies, such as Saturn and EVI electric vehicles developed by General Motors in 1980s and 1990s.

However, lead-acid battery has low specific energy, short battery life, high self-discharge rate and low cycle life. Its main raw material lead is heavy in weight, and may produce heavy metal pollution in the process of production and recovery. So currently, lead-acid batteries are mainly used in ignition devices when cars start, and small devices such as electric bicycles.

Nickel metal hydride battery

Nickel metal hydride (Ni/MH) battery has good resistance to overcharge, overdischarge capacity, there is no heavy metal pollution problem, and in the process of work will not appear electrolyte increase or decrease phenomenon, can realize the sealing design, maintenance free. Compared with lead-acid battery and nickel-cadmium battery, nickel-metal hydride battery has higher specific energy, specific power and cycle life.

Its disadvantage is that the memory effect of the battery is poor, and with the progress of the charging and discharging cycle, hydrogen storage alloy gradually loses the catalytic ability, the internal pressure of the battery will gradually rise, which affects the use of the battery. In addition, the high price of nickel metal, also leads to higher costs.

In terms of key materials, Ni-MH battery is mainly composed of positive electrode, negative electrode, diaphragm and electrolyte, and positive electrode (Ni(OH)2); Metal hydride (MH) is commonly used in the negative electrode. The electrolyte is mainly liquid, the main component is potassium hydroxide (KOH). At present, the research focus of nickel metal hydride battery is mainly on positive and negative electrode materials, and its technology research and development is relatively mature.

Nickel-metal hydride (NIMH) batteries have been produced and used in batches, and are the most popular type of vehicle battery in the development of hybrid electric vehicles. The most typical representative is currently the largest mass production of hybrid vehicles Toyota Prius. PEVE, a joint venture between Toyota and Panasonic, is the world's largest manufacturer of Ni-MH power batteries.

Now nickel-metal hydride battery has withdrawn from the mainstream power battery ranks at this stage, so why Toyota will stick to the nickel-metal hydride battery camp?

This brings us to the biggest advantage of NIMH batteries: super durability!

One of America's leading automotive media ran a comparative test on a first-generation Prius after 10 years of use. The test results show that the first-generation Prius model with Ni-MH battery has been driving 330,000 kilometers for 10 years. Compared with the data of the new car, both in fuel consumption performance and in power performance remain at the same level, indicating that the hybrid system and Ni-MH battery pack still work normally.

Moreover, even after a decade of 330,000 kilometers, the first-generation Prius has never had a problem with its nickel-metal hydride battery pack, nor has it had the fuel consumption and power performance that people suspected a decade ago would be greatly affected by reduced battery capacity. From this point of view, always rigorous conservative Japanese love for nickel metal hydride batteries does have its own unique reasons.

Fuel cell

Fuel cell is a kind of power generation device which converts chemical energy in fuel and oxidizer directly into electric energy. Fuel and air are fed separately into the fuel cell, and electricity is produced. It looks from the appearance of positive and negative electrodes and electrolytes, like a battery, but in essence it can not "store electricity" but a "power plant".

Compared with conventional chemical cells, fuel cells can be supplemented with fuel, usually hydrogen. Some fuel cells can run on methane and gasoline, but their use is usually limited to industrial applications such as power plants and forklifts. The basic principle of hydrogen fuel cells is the reverse reaction of electrolytic water. Hydrogen and oxygen are supplied to the anode and cathode respectively. After hydrogen diffuses outward through the anode and reacts with the electrolyte, electrons are released to the cathode through the external load.

Hydrogen fuel cells work by: The hydrogen gas is sent to the anode plate (negative electrode) of the fuel cell. After the action of the catalyst (platinum), an electron in the hydrogen atom is separated. The hydrogen ion (proton) with the loss of electron passes through the proton exchange membrane and reaches the cathode plate of the fuel cell (positive electrode). This creates a current in the external circuit.

When the 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, electricity can be supplied continuously as long as hydrogen is supplied to the anode plate, air is supplied to the cathode plate, and water vapor is carried away in time.

The electricity from the fuel cell, through the inverter, controller and other devices, to power the motor, and then through the transmission system, drive axle wheel rotation, can make the vehicle on the road. Compared with traditional cars, the energy conversion efficiency of fuel cell vehicles is as high as 60 to 80 percent, which is two to three times that of internal combustion engines.

Fuel cells are fueled by hydrogen and oxygen, and the product is clean water. It does not produce carbon monoxide or carbon dioxide, nor does it emit sulfur or particulates. Therefore, hydrogen fuel cell vehicle is the true sense of zero emissions, zero pollution car, hydrogen fuel is the perfect vehicle energy!