Volkswagen's "super battery" analysis doubles the endurance of electric vehicles
New energy vehicles are the focus of current car companies. Volkswagen has not been dominant in this field. In recent years, it has only launched golf electric vehicles that are actually mass-produced and sold. In order to enhance its strength in the field of electric vehicles, Volkswagen is developing "Super-battery", which can greatly enhance the cruising range of electric vehicles, and is now close to making breakthroughs in new battery technology.
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Volkswagen CEO Martin Winterkorn said in an interview with German media: "Volkswagen is developing a super battery in Silicon Valley, California. The new battery is cheaper, smaller and more powerful. An electric The version of the Volkswagen brand (after the super battery) is expected to reach 300 kilometers (186 miles) of pure electric range. This will be a leap in the quality of electric vehicles.
In contrast, the US Environmental Protection Agency EPA stipulates that the average cruising range of e-Golf pure electric vehicles should reach 83 miles (about 133 kilometers). This means that if the performance of the public "super battery" is on schedule, the mileage of the electric vehicle will reach 2.26 times that of the EPA for the golf electric vehicle. Although the 300km cruising range is still not comparable to the 265 miles of the Tesla Model S, Volkswagen will introduce an more affordable electric vehicle, such as the next generation e-Golf. Therefore, it is more meaningful than Model S in promoting the popularization of electric vehicles.
In the past 18 months, the Volkswagen Group has launched three electric vehicles, including e-Up, e-Golf (Golf) pure electric vehicles and Golf GTE. But Volkswagen is still cautious about developing pure electric vehicles.
Since the battery is far less energy-intensive than the internal combustion engine, the cruising range has long been one of the biggest weaknesses of electric vehicles. Among the new regulations introduced by many countries, only the single-charge cruising range of electric vehicles reaches a certain level before they can enjoy the preferential subsidy policy.
In the second quarter of this year, Volkswagen said that it will announce its battery selection solution for pure electric vehicles before July 2015, and is developing the next generation of lithium-ion battery cell technology, which can achieve five times the energy density of current batteries.
Outline
So, what technology will Volkswagen use to significantly increase battery energy density? And significantly improve the cruising range of electric vehicles? The current focus is mainly on the existing lithium-ion battery upgrade version of the solution, as well as the more novel solid-state battery technology.
There is speculation that the public will turn to solid-state batteries in the future (has not yet confirmed whether it is a solid-state lithium battery). In the third quarter of 2014, Volkswagen expressed optimistic about the prospects of solid-state batteries and merged into QuantumScape, a startup that develops solid-state batteries, with a 5% share.
What is the solid lithium battery that Volkswagen is optimistic about? In the structure of the battery, generally, the electrode is a metal conductor, and the electrolyte is a certain liquid. Solid-state batteries, as the name implies, use solid or gel electrolytes. Solid electrolytes are roughly classified into inorganic substances and high molecular types. Among them, the inorganic electrolyte has the characteristics of high ionic conductivity and long service life; the polymer electrolyte has the characteristics of high production efficiency.
Compared to traditional lithium-ion batteries, solid-state batteries have many advantages.
The first is energy density and energy storage characteristics. In an ideal state, the diffusion rate (ion conductivity) of solid lithium exceeds that of the liquid electrolyte, and theoretically, a higher output can be achieved. Since it is not necessary to enclose the liquid, the battery exterior can be simplified, which is both miniaturized and simplifies the production process. According to the propaganda of some companies, batteries with an energy density of 1.1 kWh per liter have been produced, which is about 50% higher than that of lithium-ion batteries. Future solid-state batteries are expected to increase several times more than current battery energy densities.
Followed by security performance. From the internal structure of the lithium ion rechargeable battery, it is the most desirable state if only lithium ions move while other ions do not move. The inorganic electrolyte is capable of moving only lithium ions. This prevents secondary reactions caused by anion movement and contributes to improved safety and durability. Traditionally, lithium-ion rechargeable batteries using organic electrolytes may cause electrolyte heating when there is an abnormality such as overcharging or internal short circuit, which may cause spontaneous combustion or explosion. The solid electrolyte of the all-solid battery is less likely to be burned than the liquid electrolyte, has a strong flame retarding ability, avoids the risk of leakage of the flammable liquid, and its safety can be greatly improved.
Further, in terms of manufacturing, the battery exterior is simplified as described above, so that a large-area battery unit can be manufactured in a roll-to-roll manner. In addition, a plurality of electrodes may be stacked and connected in series in the battery cells to manufacture a large voltage battery unit of 12V or 24V.
However, solid-state batteries currently have bottlenecks, such as in terms of process complexity. In addition, solid-state batteries have poor high-rate discharge performance and poor low-temperature characteristics.
Promising prospects
Volkswagen CEO Martin Wendern said in November last year: "I think the application potential of solid-state battery technology is huge, and it is very likely that the technology will increase the cruising range of electric vehicles to 700 kilometers."
In addition to performance, battery cost will also be the focus of breakthrough. The current price of electric vehicles is high, and the reason is that the battery composition is high.
Heinz-Jakob Neusser, a board member of the Volkswagen Group responsible for research and development, revealed to the media that all future electrified vehicles in the company may turn to a single lithium-ion battery unit design. Although the battery model specifications vary, the unified battery unit can be used in different package quantities and methods to meet various needs. The group's goal is to reduce battery costs by 66% by simplifying battery unit design.
Noosa said at the roundtable: "We clearly understand that the group needs a universal battery unit, which means that every product and brand in the group uses the same battery unit, otherwise we can not achieve synergy in the development process. Effect." But Nossa did not give a specific route switching time node.
A spokesperson said that a single battery design can take advantage of Volkswagen's battery module assembly plant capacity in Braunschweig, Germany, and even a uniform battery cell design from different battery suppliers.
At the moment, Volkswagen has adopted a variety of lithium-ion battery cells. For example, Panasonic supplies batteries for e-golf, golf GTE plug-in hybrids, and Audi A3 electric vehicles, while Samsung supplies batteries for Passat GTE and other Audi electric vehicles.
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