Five Energy Storage Battery Technologies
1, lithium battery
At present, most electric vehicles use lithium iron phosphate batteries, but there are still some difficulties in popularizing lithium electric vehicles.
(1) price. The cost of batteries accounts for more than half of electric vehicles. The latest Tesla car sells for more than 700,000 yuan, which ordinary people can't afford.
(2) Energy density. 磷酸铁锂电池的理论比容量为170wh/kg，钴酸锂电池的理论比容量为200wh/kg。 So most of the load of lithium-ion cars is spent on the weight of batteries.
(3) Safety.
(4) Charging time. Fast charging mode can fill 80% in tens of minutes, but it is harmful to the battery and dangerous. Slow charging takes several to more than a dozen hours. Manufacturers generally recommend slow charging mode.
2. Supercapacitor
It is reported that there is no reliable basis for the conclusion that "supercapacitors are expected to replace batteries". Although the energy density of the supercapacitor will be greatly increased by introducing graphite dilution, it is still far lower than that of lithium power, and the energy density of the supercapacitor is 74 wh/kg. However, the advantage of supercapacitors is that the charging time is very short (a few seconds) and safe, which can be used for auxiliary peak shaving and brake energy storage of electric vehicles.
3. Hydrogen-powered Vehicles
Hydrogen-powered automobile technology has made great progress in recent years. Its advantages are short charging time and strong power. But the problem to be solved now is
(1) Production cost of hydrogen
(2) Safe and high strength hydrogen storage tanks
(3) safety
(4) Price of inflatable equipment. Among them, the issue of security is particularly important. In addition, the environmental protection of hydrogen production process is also controversial.
4. Flow Battery
Currently, there are mainly zinc bromide flow battery and vanadium flow battery. The cost of zinc bromide flow battery is only about 1/5 of that of vanadium flow battery, which has natural advantages.
(1) price. The cost of zinc-bromide flow battery is close to that of lead-acid battery, and it can be lower in theory in the future. Only about a fifth of lithium batteries.
(2) Energy density. The energy density can reach 430Wh/kg. Driving distance is longer.
(3) Safety. Very safe.
(4) Charging time. It can be very short, fast charging mode does not damage the battery.
(5) There are other advantages such as long service life, 100% deep discharge, no self-discharge, super-high power, instantaneous charging and almost no requirement for working environment.
The above data tell us that zinc bromide batteries are the best energy supplier for electric vehicles at present.
5. Zinc-bromide batteries:
Zinc-bromine batteries are semi-deposited liquid flow batteries. In the mid-1970s, some people changed the electrolyte of zinc-bromide batteries from static to flowing, which inhibited the formation of zinc deposited dendrites. Zinc-bromide batteries became deposited liquid-flow energy storage batteries and gradually became commercialized.
Zinc-bromide batteries are semi-deposited, electrolyte is ZnBr2 aqueous solution, microporous diaphragm is placed between the electrodes, and quaternary amine ligands are added to the electrolyte to prevent the diffusion of bromine to the negative electrode. Due to the strong corrosiveness of bromine, carbon-plastic composites with high specific surface carbon layer are generally used as electrodes. In order to make the zinc coating uniform and reduce the corrosion rate of zinc, it is necessary to strictly control the pH value of the solution. In addition, it is necessary to reduce leakage current by means of battery design or electrode protection. According to reports, the United States, Japan and other countries have assembled 5-45kWh zinc-bromide batteries as power supply for electric vehicles; ZBB Energy Company has designed 400 kWh demonstration stack; Japan has assembled 1-4MWh zinc-bromide stack, the overall energy efficiency is about 65.9%.
The theoretical open circuit voltage of zinc bromide flow battery is 1.82V, which is higher than that of all vanadium flow battery. Zinc-bromide batteries operate at near room temperature without complex thermal control systems. Most of their components are made of polyethylene plastics. Cheap raw materials and low manufacturing costs make them competitive in cost. These characteristics of zinc bromide flow battery make it one of the choices of large-scale energy storage battery. Zinc-bromide batteries have been used for renewable energy generation and energy storage.
