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Advantages and disadvantages of silicon anode battery materials

2020-12-29 13:59

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The silicon-based anode has great potential. From the comparison of the performance of different anode materials, the mass/volume ratio of silicon-based anode is huge. The theoretical mass specific capacity of crystalline silicon is about 4200mAh/g, while graphite is only 372 mAh/g, which is about 11 times that of graphite. Even the silicon oxide material has a theoretical mass specific capacity of 2600mAh/g, which is about 7 times that of graphite. From this point of view, silicon-based materials are the most promising anode materials for next-generation lithium-ion batteries.

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Compared with bulk materials, silicon-based nanowire electrode materials used in lithium batteries have outstanding advantages: they have high tolerance to electrode volume changes during cycling, and can avoid damage to the electrode structure to a greater extent; large specific surface area , Which is conducive to the effective contact between the electrolyte and the electrode, shortens the charge and discharge time threshold; shortens the electron transport and ion diffusion distance, increases the battery capacity and rate; assists in the realization of other functions, such as no current collector, self-supporting, etc. Amprius’s silicon nanowire process uses a special PECVD method to grow silicon nanowires directly on the battery pole pieces, so that the silicon material can release stress well through axial expansion without causing cracks or damage to the nanowires, thereby preventing The powdering of the electrode. However, the current industrial production of nanowires is still very difficult, and there is a long way to go to completely solve the problem of expansion. Due to the high production cost of complex material structures, the difficulty of accurately controlling the growth and shape of nanowires, and the interface problems between nanowire electrodes and electrolyte are commercial The main constraints of globalization. Judging from the current progress of silicon-carbon anodes at home and abroad, if the capacity of advanced-level silicon-carbon anodes is 1500~1600mAh/g, the cycle life is about 500 times. If the doping amount of silicon material is increased to 10%, the capacity will reach 5100mAh/g. The life span is 1500-2000 times.