Sweden develops new silicon anode lithium battery

by:CTECHi     2021-07-30

Scientists in Sweden have developed a new aerogel process to manufacture silicon anodes for lithium-ion batteries, which is expected to provide batteries with a much larger capacity than those sold today. By growing nano-sized silicon particles on graphite, the research team was able to demonstrate a device that overcomes many of the challenges common to silicon as a negative electrode material. Although there are still challenges in terms of stability and capacity maintenance, this method can eventually lead to a low-cost, large-scale production process.

Swedish research and development of a new type of silicon anode lithium battery can create a low-cost large-scale production process

The use of graphite as a negative electrode material Behind it are the many limitations of today's lithium-ion batteries. Although it is a reliable material, the relatively low theoretical capacity of graphite and the tendency to lose this capacity at high current densities are two factors that hinder major improvements in the capacity and performance of commercial lithium-ion batteries.

Silicon is one of several new anode materials that researchers are vying to pay attention to. Its theoretical capacity is about ten times that of graphite, and of course it has great potential. However, during the battery cycle, silicon easily swells and then falls apart, resulting in a rapid decline in performance.

Researchers have discovered various solutions, including making silicon porous from the beginning or using a 'scaffold' structure of carbon nanotubes. However, in the early stages of this research, few people paid attention to the cost or potential scalability of the process being studied.

Scientists at the University of Central Sweden hope to solve this problem. They have studied a new process for the production of silicon anodes. The particles are coated on graphite flakes. Using this process, they produced an anode with a specific capacity of 455 milliampere hours (mAh/g-1) and a coulombic efficiency of 97% at a current density of 100 milliampere hours per gram. The details of the process and characteristics of this anode are published in 'Scientific Reports

Swedish research and development of a new type of silicon anode lithium battery can create a low-cost large-scale production process

The anode relies on graphite as an additive To improve conductivity and connect tiny silicon nanoparticles. In the first cycle, the capacity of the anode reaches 1050mAh/g-1, which is close to the theoretical limit of silicon. After 30 cycles, this value quickly drops to 57% of the initial value, and after 100 cycles it drops to 52%. The researchers pointed out that this is a significant improvement compared to the results of raw silicon, ground silicon, or heat-treated silicon. In the first cycle, the specific energy of the anode was measured to be 787 watt-hours/kg (Wh/kg), which dropped to 341.25Wh/kG after 200 cycles.

Although other methods have shown stronger results in terms of capacity retention, the researchers point out here that these methods often rely on complex or expensive processes and are not suitable for large-scale produce. The researchers said: 'Silicone nanoparticles are grown on graphite nanosheets from silicon powder and nanographite using polyvinyl alcohol (PVA) through aerogel manufacturing routes. The method is simple, cost-effective, scalable and does not require expensive equipment for synthesis In this study, we show that electrodes prepared based on this structure show high specific capacity and cycle stability, and therefore are a potentially cost-effective silicon-based anode method.'

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