The Challenge of Lithium Ion Battery
Researchers found that nearly one-third of the interviewees said that they can use electric vehicles with a cruising range of 100 miles (about 160 kilometers) to complete most of their travel activities. Only 6% of the cases involve a long travel distance, which may require the user to fully charge the battery before traveling, or rent a gasoline car.
Today, the development of electric vehicles is better. Many electric vehicles have a cruising range of more than 200 miles (about 320 kilometers), and the cruising range of some large-size and high-end models can even reach nearly 400 kilometers. After all, there are still many potential car buyers worrying that the vehicle will run out of power halfway. The long-life version of the battery can alleviate the user’s “electric vehicle mileage anxiety”, but “there are still many holes to fill.”
Many electric vehicles are equipped with lithium-ion batteries. This product is a battery design commercialized by Sony in 1991. The special feature of this type of battery is its high energy storage capacity. At present, the energy density of the on-board battery of an electric vehicle is usually 200wh/kg. Contemporary lithium-ion batteries can inject a potential of 200 watt-hour into a 1 kg battery kit. This data is 5 times that of the old lead-acid battery, and researchers are continuing to study improvements to improve the performance of lithium-ion batteries.
The name of the lithium ion battery is taken from the lithium ion inside. But when this type of battery discharges, the anode produces lithium ions. Then, the lithium ions will pass through the battery separator (only lithium ions can pass) into the electrolyte and then diffuse to the cathode. The electrons from the anode will disappear and enter the cathode along the external circuit. The current generated in this process will be used to drive the motor. At the cathode, ions and electrons recombine. This situation will continue until the user connects the vehicle with the charging device through the charging cable, and the entire process will be reversed.
For weight-sensitive applications such as vehicles, lithium metal is the lightest metal in the periodic table of chemical elements, but the metal is also highly reactive. The construction of the battery cell needs to be very careful to avoid defects, otherwise it may cause a battery short circuit or even a battery fire accident. The anode is usually composed of carbon-rich material, and the lithium metal in the cathode is usually easily partially oxidized to produce lithium cobalt oxide.
Cobalt metal is the most expensive battery material, and battery manufacturers are trying to reduce the amount of this material used. Many cobalt mines are located in the Democratic Republic of Congo, and the mining conditions are very harsh, and even child labor is used. The mainstream thinking in the industry is to reduce the amount of electric cobalt metal used in lithium batteries, while increasing the amount of nickel and manganese in order to produce NMC batteries (ternary lithium batteries).
Last year, China’s largest battery manufacturer-CATL began mass production of NMC batteries with an energy density of 240wh/kg. While other companies such as Tesla hope to further reduce or even get rid of their dependence on cobalt metal, Tesla is tight-lipped about the details of its battery plan.
In order to reduce the cost of battery materials, as the production capacity of CATL, Tesla and other rivals increases, the price of such batteries will steadily decline. According to Bloomberg New Energy Finance, the average selling price of lithium batteries in 2012 was US$1160/kWh (about 8204.68 yuan/kWh). By 2024, its selling price will be less than US$100/kWh (about 707.3 yuan/kWh) (see chart). By then, compared with diesel locomotives, the competitive advantage of electric vehicles will be greater.