Five types of new energy battery analysis
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As a relatively mature technology, lead-acid batteries are still the only batteries for electric vehicles that can be mass-produced because of their low cost and high-rate discharge. At the Beijing Olympics, there were 20 electric vehicles using lead-acid batteries to provide transportation services for the Olympic Games.
However, the specific energy, specific power and energy density of lead-acid batteries are very low, and electric vehicles using this as a power source cannot have good speed and cruising range.
Although the performance is better than that of lead-acid batteries, it contains heavy metals, which can cause environmental pollution after being abandoned.
Nickel-hydrogen battery has just entered a mature stage, and it is the only battery system that is currently verified and commercialized and scaled in the battery system used in hybrid vehicles. The current market share of hybrid batteries is 99% nickel-hydrogen battery, commercial The representative of the chemical is the Toyota Prius. At present, the world's major automotive power battery manufacturers mainly include Japan's PEVE and Sanyo. PEVE occupies 85% of the global Hybrid Ni-MH battery for power vehicles. Currently, the main commercial hybrid vehicles such as Toyota's Prius, Alphard and Estima, As well as Honda's Civic, Insight, etc., PEVE's nickel-hydrogen battery packs are used. In China, Changan Jiexun, Chery A5, FAW Pentium, General Motors and other brand cars have been in the demonstration operation, they also use nickel-metal hydride batteries, but the battery is mainly purchased abroad, the domestic nickel-hydrogen battery in the car Still in the R&D matching phase.
The traditional lead-acid batteries, nickel-cadmium batteries and nickel-hydrogen batteries are relatively mature in their own technology, but they are used as power batteries in automobiles. At present, more and more car manufacturers choose to use lithium batteries as the power battery for new energy vehicles.
Because lithium-ion power battery has the following advantages: high working voltage (three times that of nickel-cadmium battery hydrogen-nickel battery); large specific energy (up to 165WH/kg, which is three times that of hydrogen-nickel battery); small size; light weight Long cycle life; low self-discharge rate; no memory effect; no pollution.
Many well-known automakers are currently developing power lithium battery vehicles, such as Ford, Chrysler, Toyota, Mitsubishi, Nissan, Hyundai, Courreges, and Ventury. Domestic automakers such as BYD, Geely, Chery, Lifan and ZTE are also equipped with power lithium batteries in their hybrid and pure electric vehicles.
The bottleneck that currently hinders the development of power lithium-ion batteries is: safety performance and management systems for automotive power batteries. In terms of safety performance, lithium-ion battery has high energy density, high operating temperature, harsh working environment, and human-oriented safety concept. Therefore, users have very high requirements for battery safety. In the management system of the automobile power battery, since the working voltage of the automobile power battery is 12V or 24V, and the operating voltage of the single power lithium ion battery is 3.7V, it is necessary to increase the voltage by connecting a plurality of batteries in series, but it is difficult to implement the battery. Fully uniform charge and discharge, thus causing a single battery in a series of battery packs to be charged and discharged unbalanced, the battery will be undercharged and over-discharged, and this situation will lead to a sharp deterioration of battery performance, and ultimately As a result, the entire battery can not work properly, or even scrapped, which greatly affects the service life and reliability of the battery.
Lithium iron phosphate battery is also a kind of lithium battery, which has less than half the energy of lithium cobalt oxide battery, but its safety is high, the number of cycles can reach 2000 times, the discharge is stable, and the price is cheap, which becomes a new choice for vehicle power.
BYD's "iron battery", the industry believes that it is more likely to be a lithium iron phosphate battery.
Briefly, a fuel cell is a power generation device that directly converts chemical energy present in a fuel and an oxidant into electrical energy. Fuel and air are fed into the fuel cell separately, and the electricity is wonderfully produced. It looks like a positive and negative electrode and electrolyte, like a battery, but in fact it can't "storage electricity" but a "power plant."
The most promising for automobiles is the proton exchange membrane fuel cell. Its working principle is: sending hydrogen to the negative electrode, through the action of the catalyst (platinum), two electrons in the hydrogen atom are separated. Under the attraction of the positive electrode, the two electrons generate electricity through an external circuit, and the electrons lose electrons. Ions (protons) can pass through the proton exchange membrane (ie, the solid electrolyte), recombining with the oxygen atoms and electrons into water at the positive electrode. Since oxygen can be obtained from the air, as long as hydrogen is continuously supplied to the negative electrode and water (steam) is taken away in time, the fuel cell can continuously supply electric energy.
Because the fuel cell directly converts the chemical energy of the fuel into electrical energy, without passing through the combustion process, it is not limited by the Carnot cycle. At present, the fuel-electric energy conversion efficiency of a fuel cell system is 45% to 60%, while the efficiency of thermal power generation and nuclear power is about 30% to 40%.
from china energy storage net