- Category: Technology
13 Feb 2013
- Published on Wednesday, 13 February 2013 09:13
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A new lithium-ion design from the University of Southern California incorporates small voids etched in small bits of silicon to triple its energy storage capacity.
The design uses porous silicon nanoparticles in place of traditional graphite anodes. This increases its energy storage capacity and speeds up its charge cycle, allowing the battery to recharge within 10 minutes.
The new battery is currently under a provisional patent and could be commercially available within two or three years.
According to the researchers, the silicon nanoparticle anodes are a crucial part of the improved performance of the new battery design.
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A lithium-ion battery normally contains two electrodes, from which lithium ions move back and forth to create a current during the battery’s charging and discharging cycle. The anode is where the current flows into a battery, while a matching cathode is where the current flows out.
The setback with previous silicon anode designs, which were basically tiny plates of silicon material, is that they broke down two quickly during the charging cycle.
Chongwu Zhou, a professor at the U.S.C. Viterbi School of Engineering who led the team, had previous experience incorporating silicon into battery anodes.
Last year, he developed a battery anode using porous silicon nanowires. The pores on the nanowires increased the surface area of the anode and allowed the silicon to expand and contract during the charging and discharging.
By expanding and contracting during the charging cycle, the silicon material was able to avoid breaking down. The increased area also allowed the lithium ions to move through the battery faster and improve its performance.
However, the problem with the silicon nanowire-based battery was that the nanowires – which were just a few nanometers in diameter and a few microns long – were difficult to manufacture. So Prof. Zhou and his team decided to look for an alternative for their battery design.
They decided to work with commercially available nanoparticles of silicon. They etched pores into the nanoparticles and found that much of the design advantages they had found in the nanowires were also found in the nanoparticles.
The only difference in performance between silicon nanoparticle batteries and silicon nanowire batteries was the lifespan. The silicon nanoparticle batteries currently last for only 200 charge cycles. While this isn’t bad compared to the average of 500 cycles for graphite-based designs, it is far behind what the team achieved for the silicon nanowire batteries which reached up to 2,000 cycles.
The team is continuing their work on the nanoparticle battery design to further improve on its lifecycle and performance.
They will also be looking into a new cathode material to pair with the porous silicon nanowires and or porous nanoparticles to completely redesign their battery. – EcoSeed Staff