Silicon-containing material, negative electrode for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and manufacturing method therefor
A non-aqueous electrolyte, secondary battery technology, applied in secondary batteries, battery electrodes, negative electrodes, etc., can solve the problems of not reaching the practical level of cyclability, large irreversible capacity at the first charge and discharge, unsatisfactory, etc. Higher capacity, improved cyclability, and effects of improved cyclability
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Embodiment 1
[0132] A plurality of silicon-containing materials (sample numbers 1 to 6) in which a carbon film was formed were prepared by the following method.
[0133] Silicon oxide powder (SiO x : x = 1.02) 200 g is loaded into a tray made of silicon nitride, and then left to stand in a treatment furnace capable of maintaining the environment. In the silicon oxide powder, the amount of particles with an average particle diameter of 2 μm and 0.5 μm or less is 25 %. Next, argon gas is flowed in, and after the argon is replaced in the processing furnace, the methane-argon mixed gas is flowed in at a flow rate of 2 NL / min, while the temperature is raised at a rate of 300°C / hr, and the temperature is set at a temperature of 600°C to 1000°C. By keeping for 3 to 10 hours, thermal CVD of the carbon film is performed. After the hold is over, the temperature is lowered, and when it reaches room temperature, the powder is recovered. The carbon deposition amount of the obtained conductive silico...
Embodiment 2
[0155] The silicon-containing material in Example 1 was made of silicon oxide powder and coated with carbon. In Example 2, it was confirmed whether the effects of the present invention (high circularity). Fabrication of conductive silicon composite powder pre-doped with lithium, which is sometimes used to improve first-time efficiency when actually constituting a battery. The lithium-doped conductive silicon composite powder was specifically obtained by using the conductive silicon obtained in Example 1 with a discharge capacity ratio of 45.1% to 400 mV (sample number 6). The composite powder is obtained by kneading and mixing 5% metal lithium in the presence of an organic solvent, and then drying; the thus obtained conductive silicon composite powder doped with lithium is heated at 300°C under an argon atmosphere The temperature was raised at a heating rate of / hr, and kept at a temperature of 500°C to 800°C for 3 to 8 hours. Using this method, a plurality of lithium-doped ...
Embodiment 3
[0161] Silicon oxide powder (SiO x : x = 1.02) 200g, put into the tray made of silicon nitride, and leave it in a treatment furnace capable of maintaining the environment. The average particle diameter of the silicon oxide powder is 3 μm, and the BET specific surface area is 12m 2 / g. Next, argon gas is flowed in, and after argon replacement is carried out in the processing furnace, while flowing argon gas at a flow rate of 2 NL / min, the temperature is raised at a rate of 300°C / hr, and the temperature is maintained at 600°C to 1000°C for 3~ 10 hours. After the holding was completed, the temperature was lowered, and when the room temperature was reached, powders were recovered (sample numbers 9 to 11).
[0162] [battery evaluation]
[0163] The obtained silicon composite powder was subjected to battery evaluation in the same manner as in Example 1, and the capacity retention rate at the 20th cycle was determined. As a result, as shown in Table 3, an excellent value of 99.8%...
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Abstract
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