What is the energy density of lithium batteries that is close to the theoretical limit?
In recent years, due to the rapid development of new energy vehicles, the matching power battery technology has also been making new breakthroughs. The energy density of batteries has been greatly improved compared to a few years ago. However, recently, academician Sun Shigang has sounded the alarm for my country's battery companies. He said that the energy density of existing lithium-ion batteries is close to the theoretical limit.
On November 9, at the China (Suining) International Lithium Battery Industry Conference and the International Exchange Conference on New Energy Vehicles and Power Batteries, Sun Shigang, academician of the Chinese Academy of Sciences and professor of Xiamen University, said that the current development of my country's lithium battery industry is faced with the challenges of resources, energy, and safety. , usage environment and other four major challenges.
The first is the consumption of resources. According to Sun Shigang, currently, 0.5kg of lithium is used to produce 1KW lithium-ion battery. According to the latest survey data from the United States Geological Survey, the world’s metallic lithium reserves are about 13.5 million tons (the total lithium resource reserves are about 39.5 million tons). Available for over 100 years. my country's lithium resources rank sixth in the world. The resources are mainly salt lakes. The lithium content is low, the magnesium-lithium ratio is high, and it is difficult to extract. 70% of lithium depends on imports. It is expected that by 2025, my country's lithium battery production capacity will reach about 3900GWh, and it is expected to require About 390,000 tons of lithium metal.
Secondly, the energy density of existing lithium-ion batteries is close to the theoretical limit. "The energy density of the battery is related to the principle of the battery. For example, the energy density of the lithium-ion battery is related to the reaction electron beam and the weight and density of the active material," Sun Shigang said. The current energy density of the lithium-ion battery is close to the ceiling.
It is understood that the current energy density of mainstream LFP batteries is below 200Wh/kg, and the energy density of ternary lithium batteries is between 200-300Wh/kg. The energy density of lithium-ion batteries is far from meeting the needs of major developments, limiting its application in multiple scenarios. To increase the speed and range of drones and other equipment, it is necessary to significantly increase the energy and power density of batteries.
It is worth mentioning that just last month, NASA announced that it had successfully developed a sulfur-selenium pure solid-state battery. The electrolyte material uses cheap and easily available sulfur and does not contain liquid. The battery energy density has reached 500Wh/kg, which is currently Tesla’s Pulls approximately twice as much as a 4680 cylindrical lithium-ion battery. NASA announced that this technology will be promoted on electric aircraft in the future.
Sun Shigang pointed out that the challenges faced by existing lithium-ion batteries also include frequent safety accidents. Lithium-ion batteries are prone to battery thermal runaway. Common reasons include overcharging inducing gas production in the battery's positive electrode material, causing the battery to burst, fast charging causing lithium precipitation in the battery's negative electrode and inducing a short circuit, and fast charging causing the electrolyte liquid to burn due to rapid temperature rise.
Finally, the battery usage environment is limited. In a low-temperature environment, the viscosity of the electrolyte of lithium-ion batteries will increase, the ion migration speed will slow down, and the charge and discharge energy will decline sharply. At high temperatures, the interfacial membranes between the positive and negative electrodes of the battery are unstable, leading to damage to the material structure and gas production that can lead to explosions. In application scenarios such as deep space and deep sea, batteries require a higher and wider temperature range.
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