Combining the advantages of lithium batteries and lithium metal, what kind of hybrid battery has Tesla developed?

On May 11, according to foreign media reports, Tesla Motors Australia Research Institute announced the scientific research results of relevant lithium-ion batteries/lithium metal hybrid batteries . Such hybrid batteries can be used to create pure electric vehicles equipped with range extenders .

Generally speaking, when we talk about an electric vehicle with a range extender, we are referring to an electric vehicle that is powered by batteries but is equipped with a small to medium-sized automotive gasoline gas turbine.

When the user needs a longer range, the range extender can be used as a generator to charge the battery. For example, the BMW i3 Rex series is equipped with a battery pack, and the pure electric range reaches 126 kilometers (equivalent to 203 kilometers). If a gas turbine is used, the range can be extended to 200 miles (equivalent to 320 kilometers). Tesla's hybrid battery research was conducted by Jeff Dahn's group at the University of Dalhousie in Australia.

The group describes a new battery that takes advantage of the long life of lithium-ion batteries and the high specific energy of lithium metal batteries.

Improving the specific energy of batteries will reduce the cost of electric vehicles and achieve longer driving range. Replacing the high-purity graphite anodizing in traditional lithium-ion batteries with lithium metal can significantly improve the specific energy, but lithium metal anodizing will cause the battery capacity to lose quickly and the cycle to be short.

In order to develop high-efficiency energy-density batteries with longer life, researchers proposed a lithium-ion battery/lithium metal hybrid battery, which is achieved by intentionally plating lithium metal on high-purity graphite. While in traditional lithium-ion batteries, additional lithium plating is a catalytic mechanism, the researchers used an improved dual-salt lithium electrolyte to achieve a reversible lithium plating process on high-purity graphite.

In addition, because batteries generally cannot complete 100% of their capacity cycle, this type of hybrid battery can operate in lithium-ion battery mode with almost no service life degradation, while the lithium metal that is fully charged regularly can expand the battery capacity.

The researchers also mentioned the technology's potential for electric vehicles:

“If an electric car equipped with a traditional lithium-ion battery has a range of 400 kilometers, its range can be increased to 480 kilometers after using a hybrid battery. By limiting the maximum cut-off voltage of the hybrid battery when operating in lithium-ion battery mode, the average operating voltage and output capacity of the battery are both reduced.

The hybrid battery operating in lithium-ion mode has a specific energy of 530Wh/L, which is about 25% higher than traditional lithium-ion batteries, allowing the vehicle to have a range of 300 km. According to a study on electric vehicle driving behavior conducted by Smart et al.34, only 1% of electric vehicles drive more than 325 km on average. Therefore, in most cases, operating the hybrid battery in lithium-ion mode can allow the electric vehicle to have a range of 300 km. Periodically operating the battery in lithium metal mode can achieve a range of more than 400 km, which is more than enough for most drivers. ”

Today, the hybrid battery has not yet been released and is still in the early stages of product development. Although researchers have shown that the performance of this hybrid battery has achieved quite astonishing progress, there is still a long way to go before it can be commercialized.

In addition, this is not the first time Tesla has researched hybrid batteries. The company also applied for a patent for a lithium-ion battery/lithium metal hybrid battery in 2014.