As the anode material of lithium ion battery, silicon nanopowder has the highest theoretical specific capacity (up to 4200 mAh/g), which is much higher than the carbon powder widely used at present, but the biggest disadvantage of silicon powder as the negative electrode of lithium ion battery is the process of alloying with lithium.
In the case of a large volume change, the active material is detached during the cycle, so that the capacity is quickly attenuated and the cycle performance is poor. At present, in order to solve this problem, researchers have used silicon nanopowder/titanium nitride nanopowder/titanium carbide nanopowder as composite materials. Experiments show that they have stable cycle performance, and TiN, TiC and other phases act as inert components to stabilize the structure. Its role is mainly manifested in: during the discharge process, it buffers the volume expansion during the formation of LiSi, inhibits the capacity decay caused by the pulverization of the alloy due to alloy pulverization, and in the charging process, To prevent the agglomeration of Si particles. In addition, TiN, TiC and the like have good electrical conductivity and enhance the conductivity of the electrode. Due to the high absorption rate of nano-silicon and lithium batteries, the use of nano-silicon for lithium batteries can greatly increase the capacity of lithium batteries (theoretical can reach 4000 mA / h).
Silicon nanopowder and graphite powder were used as raw materials to replace carbon nanopowder. As a negative electrode material for lithium battery, silicon/graphite composites were prepared by mechanical ball milling. The materials were characterized by XRD, SEM and electrochemical tests. Performance test. The best ratio of silicon to graphite was found by ball milling different amounts of silicon and graphite, and the corresponding composites were tested for charge and discharge. The value was 1:9. The composition of the Si-C composite material can effectively reduce the expansion due to the absorption of lithium ions by the silicon, and at the same time, the affinity with the electrolyte can be increased, the dispersion is easy, and the cycle performance is improved.
The nano silicon wire is made of nano silicon powder and used in the negative electrode material of the rechargeable lithium battery, or the surface of the nano silicon powder is coated with graphite as the negative electrode material of the rechargeable lithium battery, which can improve the capacity and charge and discharge of the rechargeable lithium battery more than 3 times. Cycles.
The experimental results show that the obtained material not only has higher cycle performance than pure nano-silicon, but also has higher reversible capacity than graphite, and greatly increases the capacity of lithium battery. When the mass ratio of silicon to graphite is 4:6, the capacity decays faster, and the capacity after the 25 cycles is 200 mA.h/g, so the content of silicon in the composite should not be too large. If the content of silicon is large, the graphite is caused.
The silicon is not well dispersed, the chance of contact between the nano-silicon is increased, and agglomeration occurs, and the coulombic efficiency and cycle performance are reduced. When the mass ratio of silicon to graphite is 3:7, the composite after 25 cycles Although the reversible capacity is larger than the reversible capacity when the mass ratio of silicon to graphite is 4:6 (about 240 mA.h/g), the attenuation is still very fast as seen from the curve. The mass ratio of silicon to graphite is 1:9 and 2 At 8 o'clock, the cycle performance is better, and 1:9 is the best.
Since the price of nano-silicon is much higher than that of graphite, it is more economical and purer than the 1:9 ratio of silicon and graphite. Compared with graphite, the first reversible capacity of the composite with mass ratio of 1:9 is greatly improved, which is more than twice that of graphite. The cycle performance is also good, reaching 310mA.h/g after 30 cycles. Silicon and silicon-containing materials as lithium-ion batteries The negative electrode material has a high specific capacity, the theoretical capacity of silicon is 4200 mA.h/g, and the graphite/nanosilicon composite prepared by mechanical ball milling It is used as a negative electrode material for lithium ion batteries.
The composite material exhibits high lithium storage capacity and good graphite cycle performance and small volume effect. The experimental results show that the optimal silicon/graphite mass ratio is 1:9. The performance test shows that the cycle performance of the composite material is greatly improved compared with the pure silicon electrode and has a reversible capacity higher than that of graphite. It is expected to replace graphite as the anode material of the new generation lithium ion battery.
The main purpose:
1. Nano silicon wire is made of nano silicon powder for use in the negative electrode material of rechargeable lithium battery, or graphite coated on the surface of nano silicon powder is used as negative electrode material for rechargeable lithium battery, which improves the capacity and charge of rechargeable lithium battery more than 3 times. The number of discharge cycles.
2. Nano silicon powder is used in high temperature resistant coatings and refractory materials.
3. The nano silicon powder is mixed with the diamond under high pressure to form a silicon carbide---diamond composite material, which is used as a cutting tool!
In the case of a large volume change, the active material is detached during the cycle, so that the capacity is quickly attenuated and the cycle performance is poor. At present, in order to solve this problem, researchers have used silicon nanopowder/titanium nitride nanopowder/titanium carbide nanopowder as composite materials. Experiments show that they have stable cycle performance, and TiN, TiC and other phases act as inert components to stabilize the structure. Its role is mainly manifested in: during the discharge process, it buffers the volume expansion during the formation of LiSi, inhibits the capacity decay caused by the pulverization of the alloy due to alloy pulverization, and in the charging process, To prevent the agglomeration of Si particles. In addition, TiN, TiC and the like have good electrical conductivity and enhance the conductivity of the electrode. Due to the high absorption rate of nano-silicon and lithium batteries, the use of nano-silicon for lithium batteries can greatly increase the capacity of lithium batteries (theoretical can reach 4000 mA / h).
Silicon nanopowder and graphite powder were used as raw materials to replace carbon nanopowder. As a negative electrode material for lithium battery, silicon/graphite composites were prepared by mechanical ball milling. The materials were characterized by XRD, SEM and electrochemical tests. Performance test. The best ratio of silicon to graphite was found by ball milling different amounts of silicon and graphite, and the corresponding composites were tested for charge and discharge. The value was 1:9. The composition of the Si-C composite material can effectively reduce the expansion due to the absorption of lithium ions by the silicon, and at the same time, the affinity with the electrolyte can be increased, the dispersion is easy, and the cycle performance is improved.
The nano silicon wire is made of nano silicon powder and used in the negative electrode material of the rechargeable lithium battery, or the surface of the nano silicon powder is coated with graphite as the negative electrode material of the rechargeable lithium battery, which can improve the capacity and charge and discharge of the rechargeable lithium battery more than 3 times. Cycles.
The experimental results show that the obtained material not only has higher cycle performance than pure nano-silicon, but also has higher reversible capacity than graphite, and greatly increases the capacity of lithium battery. When the mass ratio of silicon to graphite is 4:6, the capacity decays faster, and the capacity after the 25 cycles is 200 mA.h/g, so the content of silicon in the composite should not be too large. If the content of silicon is large, the graphite is caused.
The silicon is not well dispersed, the chance of contact between the nano-silicon is increased, and agglomeration occurs, and the coulombic efficiency and cycle performance are reduced. When the mass ratio of silicon to graphite is 3:7, the composite after 25 cycles Although the reversible capacity is larger than the reversible capacity when the mass ratio of silicon to graphite is 4:6 (about 240 mA.h/g), the attenuation is still very fast as seen from the curve. The mass ratio of silicon to graphite is 1:9 and 2 At 8 o'clock, the cycle performance is better, and 1:9 is the best.
Since the price of nano-silicon is much higher than that of graphite, it is more economical and purer than the 1:9 ratio of silicon and graphite. Compared with graphite, the first reversible capacity of the composite with mass ratio of 1:9 is greatly improved, which is more than twice that of graphite. The cycle performance is also good, reaching 310mA.h/g after 30 cycles. Silicon and silicon-containing materials as lithium-ion batteries The negative electrode material has a high specific capacity, the theoretical capacity of silicon is 4200 mA.h/g, and the graphite/nanosilicon composite prepared by mechanical ball milling It is used as a negative electrode material for lithium ion batteries.
The composite material exhibits high lithium storage capacity and good graphite cycle performance and small volume effect. The experimental results show that the optimal silicon/graphite mass ratio is 1:9. The performance test shows that the cycle performance of the composite material is greatly improved compared with the pure silicon electrode and has a reversible capacity higher than that of graphite. It is expected to replace graphite as the anode material of the new generation lithium ion battery.
The main purpose:
1. Nano silicon wire is made of nano silicon powder for use in the negative electrode material of rechargeable lithium battery, or graphite coated on the surface of nano silicon powder is used as negative electrode material for rechargeable lithium battery, which improves the capacity and charge of rechargeable lithium battery more than 3 times. The number of discharge cycles.
2. Nano silicon powder is used in high temperature resistant coatings and refractory materials.
3. The nano silicon powder is mixed with the diamond under high pressure to form a silicon carbide---diamond composite material, which is used as a cutting tool!
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