Negative electrode active material for lithium secondary battery, preparation method thereof, and lithium secondary battery comprising same
A negative electrode active material and negative electrode technology, applied in the field of negative electrode active materials and their preparation, can solve problems such as battery performance degradation, achieve the effects of improving life characteristics, improving electrical conductivity, and increasing physical binding force
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Embodiment 1
[0070] Gold (Au) is set to have an average particle diameter (D 50 ) on the graphite particles and place the graphite particles and Au in a batch reactor. The temperature of the reactor was maintained at about 400 °C and then SiH 4 while performing the VLS reaction. As a result, silicon nanowires having a diameter of 10 nm to 100 nm and a length of 2 μm were grown on the graphite particles. The weight of silicon nanowires can be controlled according to the reaction time. In this embodiment, the weight ratio of graphite to silicon nanowires is 92% by weight: 8% by weight.
[0071] Wet coating was performed by immersing graphite with silicon nanowires grown thereon in ethanol (6 wt % pitch-ethanol solution) in which coal-derived pitch was diluted, and then performed at 400 °C in an argon atmosphere Heat treatment to prepare a negative electrode active material including graphite on which silicon nanowires are grown and a carbon coating on the surface of the silicon nanowires...
Embodiment 2
[0076] With the negative electrode active material prepared in embodiment 1, styrene-butadiene rubber (SBR) as binder, carboxymethyl cellulose (CMC) as thickener and acetylene black as conductive agent with 95:2:2 :1 weight ratio was mixed and the mixture thus obtained was mixed with water as a solvent to prepare a uniform negative electrode slurry. One surface of the copper current collector was coated with the prepared negative electrode slurry to a thickness of 65 μm, dried and rolled. The anode was subsequently prepared by punching to a predetermined size.
[0077] Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70, and LiPF 6 Added to the thus prepared non-aqueous electrolyte solvent to prepare 1M LiPF 6 non-aqueous electrolyte.
[0078] In addition, a lithium foil was used as a counter electrode, that is, a positive electrode, a polyolefin separator was disposed between the two electrodes, and then an electrolytic solution was in...
experiment example 1
[0082]
[0083] Carry out SEM analysis to determine the growth degree of silicon nanowires respectively on the negative electrode active material prepared in Comparative Example 1 and Example 1, and its result is shown in respectively figure 2 with image 3 middle.
[0084] specifically, figure 2 (a) to 2(c) show SEM images of the surface of the negative electrode active material without carbon coating prepared in Comparative Example 1 according to the magnification, and image 3 (a) and image 3 (b) shows SEM images of the surface of the negative electrode active material including the carbon coating prepared in Example 1 according to magnification.
[0085] Such as figure 2 with image 3 As shown in , it can be confirmed that silicon nanowires were grown on graphite particles in Example 1 and Comparative Example 1. In particular, as image 3 As shown in , it can be confirmed that the carbon coating is included on all graphite particles and silicon nanowires.
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Abstract
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