Preparation method of lithium silicon alloy membrane electrode used for lithium ion battery

Abstract

The invention discloses a preparation method of lithium silicon alloy membrane electrode used for lithium ion battery. The lithium silicon alloy membrane electrode used for lithium ion battery is obtained by the steps of adopting electrolytic deposition method and multiple current step technology under argon protection, taking anhydrous organic solvent or ionic liquid containing silicon compound and lithium salt as electrolyte and realizing the co-deposition of silicon and lithium through electrochemical reduction on a metal current collector. By changing the composition of the electrolyte andthe parameters of the multiple current step technology, the cycle capacity and primary cycle efficiency of the lithium silicon alloy membrane electrode can be effectively regulated and controlled. The obtained lithium silicon alloy membrane electrode is used as the negative electrode of a lithium ion battery, the primary cycle efficiency is 45.0 percent -150.0 percent, the charge and discharge capacity is 50.0-1000.0MumAh cm<-2> and the cycle stability is good.

Description

technical field [0001] The invention relates to a preparation method of a battery electrode material, in particular to a preparation method of a lithium-silicon alloy film electrode for a lithium ion battery. Background technique [0002] At present, graphite and modified graphite are widely used as negative electrode materials in commercial lithium-ion batteries, but the theoretical lithium storage capacity is low (graphite is 372mAh g -1 ), prone to organic solvent co-intercalation and other shortcomings, so the research and application of anode materials for high-capacity lithium-ion batteries has become the key to improving battery performance. Among the known lithium storage materials, silicon has the highest theoretical capacity (about 4200mAh g -1 ) and relatively moderate lithium intercalation potential (about 0.1-0.5V vs. Li / Li + ), very suitable as the negative electrode material of lithium ion battery (J.O.Besenhard, J.Yang et.al., J Power Sources, 1997, 68:87)....

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Problems solved by technology

[0006] Electrochimica Acta magazine, Volume 53, 2008, page 8149, reported the preparation of a 300nm thick amorphous Si-Al film by magnetron sputtering, with a mass percentage of Al of 18.08%, and a specific capacity of 2100mAh g in the first 10 cycles at a rate of 0.5C. -1 , excellent cycle performance, the capacity retention rate after 350 cycles is 80.2%; the reversible capacity of several micron thick amorphous silicon film electrodes prepared by Sanyo Corporation of Japan using RF magnetron sputtering technology reaches 3000mAh g -1 Above, the efficiency is close to 100%, and the electrode can be cycled stably for dozens of times. However, the morphology and performance of the thin film electrode are affected by many factors such as the roughness of the copper substrate, the properties of the Si / Cu interface, and the thickness of the silicon film. The result is a reproducible process. It is difficult to control (M.Shima, H.Yagi, et.al., US patent 6887511B1(2005))

[0007] Although the silicon-based thin film material prepared by the above method has high capacity and excellent cycle performance, special equipment is required for material preparation, and the process is complicated and the cost is high, making it difficult to mass-produce rapidly.

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