This summer, APRA-E, the Advanced Research Projects Agency of the US Department of Energy, invested US$36 million to help researchers develop next-generation battery designs and lay a solid foundation. Including 22 technical projects, without exception, the goal is to make electric vehicles more efficient and lower cost.

　　Ni-MH battery: from hybrid vehicles to pure electric vehicles

　　Michael Fetcenko, a chemical engineer at BASF, is one of many battery researchers. With funding from APRA-E, he tried to extend the application of nickel-zinc battery technology originally used in hybrid vehicles to pure electric vehicles.

　　Generally speaking, the energy density of NiMH batteries is 1 kWh/kg. To apply it to pure electric vehicles, BASF must increase the energy density of nickel-metal hydride batteries to 30-50 kWh/kg. The key to the success of this application lies in whether the energy density of the nickel-hydrogen battery can be increased to the required value and the cost can be reduced.

　　One possible way to achieve this goal is to replace the rare earth elements needed in the battery. Rare earth elements are a collective term. There are 17 kinds of elements in this group. The reason why they are called rare earth elements is not because of their low reserves, but because they are mainly found in mines, and the development process will consume a lot of costs. In traditional nickel-hydrogen batteries, more than 50% of the energy is generated by the reaction of rare earth elements. However, the storage performance of this type of element is poor.

　　In order to solve this problem, BASF tried to use low-cost metal hydride alloys. Professor Fetcenko believes that this material can improve the chemical performance of nickel-metal hydride batteries and reduce their cost. However, for pure electric vehicles, improving the chemical properties of nickel-hydrogen batteries is not enough to replace lithium batteries, because lithium batteries also have a vital feature-light weight, or low density.

　　Zinc-air battery: from hearing aids to cars

　　A California company called EnZinc believes that zinc-air batteries will lead the next generation of electric vehicle battery technology. Michael Burz, head of the company's related research team, said that the next generation of electric vehicle batteries should have three elements: high performance, safety, and low cost. He and his team are trying to change the design pattern/architecture of the battery to achieve these three points.

　　He pointed out that the structure of the battery has not changed for more than 100 years, and people still have not been able to think outside the box. The so-called battery architecture includes three elements: positive electrode, negative electrode, and electrolyte. The positive electrode releases electrons, and the negative electrode receives electrons. The positive electrode and the negative electrode are separated by the electrolyte, and the electrolyte acts as a medium for the free flow of ions.

　　"In lithium-ion batteries, lithium ions move from the lithium oxide positive electrode to the carbon-based compound negative electrode, and organic electrolytes are used. The zinc-air battery is different. The positive electrode uses carbon to absorb oxygen in the air, and the negative electrode is a zinc alloy. Zinc is also a benign substance, and its by-product in the battery is zinc oxide, which is the main component of sunscreen.

　　Through the above method, the zinc-air battery can achieve the three characteristics of high efficiency, low cost and safety.

　　In that case, why not popularize the technology now? That is, zinc-air batteries cannot be charged. This is why it is currently only used in small devices such as hearing aids. In order to allow the zinc-air battery to be charged, EnZinc has developed a new solution that puts ordinary oxygen and zinc metal in an alkaline electrolyte, and generates electricity through the oxidation reaction of zinc. After recharging, the oxygen and zinc can be used again. Regeneration, such a reciprocating cycle, improves the energy density of the battery.