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The revolution of lithium-air batteries: Why did scientists regain interest after the 2000s?
Lithium-air battery (Li-air) is a metal-air electrochemical battery that uses the oxidation reaction of lithium at the anode and the reduction reaction of oxygen at the cathode to generate electric current. Scientists speculate that combining lithium with ambient oxygen could theoretically lead to electrochemical cells with the highest possible specific energy. According to research, theoretically anhydrous lithium-air batteries can reach a specific energy of approximately 40.1 MJ/kg in a charged state (using Li2O2 as a product and excluding oxygen mass), which is comparable to the theoretical specific energy of gasoline of approximately 46.8 MJ/kg. Very close.
Although the current lithium-air battery has not yet reached the theoretical level in performance, its potential specific energy is about five times that of commercial lithium-ion batteries and can achieve a range of about 500 kilometers, which has once again attracted the attention of the scientific community this technology.
Historically, the concept of lithium-air batteries was proposed as early as the 1970s, initially as a power source for electric vehicles and hybrid vehicles. But due to the technical challenges faced by the battery, including reverse charging time, sensitivity to nitrogen and water, and poor internal conductivity of the battery, the concept was considered at the time to have disproportionate risks compared to the benefits. As a result, research into lithium-air batteries progressed slowly until the late 2000s, when the field regained attention due to advances in materials science.
Design and operation mechanism
The basic operating principle of lithium-air batteries is that lithium ions move between the anode and cathode in the electrolyte. During battery discharge, electrons are converted into electrical energy through an external circuit, while lithium ions move to the cathode. During charging, lithium metal is deposited on the anode and oxygen is released from the cathode.
Challenges of Cathode and Anode
In the design of lithium-air batteries, lithium metal is often used as the anode. Lithium releases electrons at the anode, but this also makes the anode face multiple challenges, such as reaction with the electrolyte, dendritic lithium deposition, and chemical changes at the electrolyte interface. These challenges can result in reduced energy capacity or the risk of short circuits.
On the cathode side, the oxygen reduction reaction also faces the problems of excessive product accumulation and low catalyst efficiency, which greatly affects the essential performance of lithium-air batteries.
Electrolyte innovation
In order to solve the above technical challenges, researchers have begun to explore a variety of electrolyte designs, including aqueous acidic, alkaline and anhydrous electrolytes. Each electrolyte approach has its specific advantages and disadvantages, but there is room for further improvement.
Commercialization and future prospects
Although the performance of lithium-air batteries in the laboratory is encouraging, there are still many difficulties to overcome on the road to commercialization. For example, issues such as long-term stability and cycle life need to be addressed. The automotive industry's demand for batteries, especially high-energy-density batteries, remains the main driving force for the development of lithium-air batteries.
Given the dual pressures of power demand and environmental concerns, scientists’ research will never stop. Will a breakthrough solution be found in the future that will lead to the commercialization of lithium-air battery technology?
In the future, lithium-air batteries have the potential to become the mainstream choice for driving electric vehicles. This is not only because their high energy density can significantly increase cruising range, but also because they may make the storage of renewable energy more efficient. However, the limitations of current technology require researchers to continue to work hard and explore more innovative paths. Will one day lithium-air batteries really change our way of electric travel?
