During use, the lithium ion battery can perform secondary charging, belonging to a secondary rechargeable battery, and the important working principle is repeated movement between lithium ions between the positive and negative poles, regardless of the shape of the battery, its important part Both are electrolyte, positive electrode, negative electrode, and diaphragm. At present, the production place of the International Lithium Ion Battery is important in my country, Japan and South Korea, and the important lithium-ion application market is mobile phones and computers and cars..
With the continuous development of lithium-ion batteries, the application field is also gradually expanded, and its use in the use of the positive electrode material has been converted in a single-diversified direction, including: olivine type phosphate phosphate, layered cobalt acid Lithium lithium, spinellate type manganese acid, etc., to achieve a variety of materials. It can be seen from the development of technology development, and more new positive electrode materials will also appear in the future development.
. With regard to the positive material material of the power lithium battery, it has a stricter requirement in various aspects such as cost, safe performance, cycle capacity, and energy density..
In the field of application materials, due to the high cost of lithium cobaltate, the safety is low, and therefore, in the specific use, it is commonly suitable for ordinary consumer batteries, and it is difficult to conform to the related requirements of the power lithium battery.. Other materials listed above have been fully utilized in the current power lithium battery.
. In a lithium-ion battery material, the negative electrode material is an important part, which can have a large impact on the performance of the overall battery..
At present, the negative material is important to be divided into two categories, a carbon material for commercial applications, such as natural graphite, soft carbon, etc., the other is in the development state, but the market prospect is a good non-carbon negative material, For example, silicon-based materials, alloy materials, tin gold materials, etc..
Figure / Silicone Carbon Negotic Material Structure Schematic The material of the carbon negative electrode material This type of material is in terms of energy density, cycle capacity, or cost input, etc., which are in an important material that is equilibrium, and is also an important material that promotes the birth of a lithium ion battery. Carbon material can be divided into two categories, ie graphitized carbon materials and hard carbon.
Among them, the former is important including artificial graphite and natural graphite. The formation process of artificial graphite figure artificial graphite is: in a temperature above 2500 ° C, after graphitization treatment of soft carbon material, MCMB is a relatively commonly used in artificial graphite, its structure is spherical, surface texture Smooth, diameter is approximately 5-40μm. Due to the effect of the surface of the surface, the reaction between the electrode surface and the electrolyte, thereby reducing the irreversible capacity.
At the same time, the spherical structure can facilitate lithium ions to embed and out of activities in any direction, and have a large promotion of support for the stability of the protection structure.. Natural graphite also has many advantages, with high crystallinity, more inserted, and low price, is a more ideal lithium ion battery material.
However, there is also a certain drawback, for example, when the reaction is reacted with the electrolyte, there is a poor compatibility, and there are many defects in the surface of the pulverization, which will have a large adverse effect on the performance of its charging or discharge.. Further, the formation process of hard carbon is: in a state of 2500 ° C, it is difficult to implement graphitized carbon material, which is important to the pyrolysis of the polymer compound, and can be seen by a high-magnification microscope, which is accumulated by many nanometer balls.
, The overall showcase. At the surface of its surface having a large amount of nanoporous amorphous areas, far exceeds the standard capacity of graphite in terms of capacity, and thereby impact on circulatory ability..
Silicon-negative material is relatively abundant due to the storage capacity of silicon substances, and it is very ideal for applications as new negative electrode materials to lithium ion batteries.. However, since silicon belongs to semiconductors, the conductivity is poor, and the volume can expand in the conventional number, the maximum expansion is 370%, which will result in active silicon powder and fall off, difficult to electronically Complete contact, thereby so that the capacity is rapidly reduced.
The figure / nanoicon silica composite anode material is to obtain a good application in a lithium ion battery material, which can effectively control its volume in the process of charging or discharging, thereby causing its capacity and The loop capability is greatly guaranteed, and the following ways can be used, first, using nano-sized silicon. Second, combined with silicon and non-active matrix, active matrix, adhesive. Third, using silicon films, it has been considered as the next generation of commercial negative electrode materials.
Lithium-ion battery positive material 1. Lithium cobaltate as a positive material, the first time, and until it still belongs to the mainstream positive material in consumer electronics. The lithium cobaltate and other positive electrode materials can be seen that the voltage is relatively stable during the operation, charging, or discharge, can conform to the requirements of large current, with strong cycle performance, high conductance efficiency, material And the battery is more stable.
The lithium cobalt-cobaltate crystal structure has also present there much of disadvantages, such as the shortage of resources, more expensive, cobalt contains toxicity, and has a certain danger when used, and will adversely affect the environment. In particular, its safety cannot be effectively guaranteed, which will become an important factor restricting its extensive development..
In the study of this, metal cations such as Al3 +, Mg2 +, Ni2 + is most widely doped. With the continuous advancement of scientific research, metal cation-doping forms such as Al3 + and Mg2 + have begun to put into use..
In terms of the preparation of lithium cobaltate, it is important to include two methods, namely solid phase synthesis, and liquid phase synthesis.. The high temperature solid phase synthesis method is commonly used in the industry.
It is important to use a lithium salt, such as Li2CO3 or LiOH, and a cobalt salt such as COCO3 or the like, which is fused according to the ratio of 1: 1, and at 600 ° C to 900 ° C high temperature. Calcination in the state. At present, the application of lithium cobaltate materials in the market is important as the secondary battery market, and it has also become the best choice for small high-density lithium-ion battery materials.
. 2. The ternary positive material has a more significant three-dimensional synergistic effect, and the lithium cobaltate can be seen that there is a large advantage in thermal stability, and the production cost is relatively low, it can become the best of lithium cobaltate.
Replace material. However, the density is low, and the cycle performance needs to be improved..
In this regard, adjustment of improved synthetic processes and ion doping or the like can be used.. Figure / Trimetic Positive Neighbor Material Comprehensive Performance illustrates the important application of the three-dimensional material to a cylindrical lithium ion battery such as steel shell, aluminum shell, but due to the influence of expansion factors, it is limited due to the influence of expansion factors.
. In future applications, there are two aspects of development direction: first, towards high manganese orientation, important in small portable equipment such as Bluetooth, mobile phones..
Second, in the field of electric bicycles, electric vehicles, etc. in the high-nickel direction, and is important in the field of energy density demand..
3. A ferrite has good cycle performance and thermal stability in charging and discharging, and has strong security during use, and the material is green and environmentally friendly, and it will not cause serious damage to the environment. It is more low, and the battery industry is considered to be the best material produced by large battery modules.
. The current important applications are: electric vehicles, portable mobile charging power, etc..
Figure / Lithium-phosphate ion battery internal structure 4. Lithium manganate has strong safety and anti-replenishment, because my country’s manganese resources are relatively rich, therefore the price is relatively low, small pollution is small, non-toxic Harmless, industrial preparation operation is simple. However, in the process of charging or discharging, since the spinel structure is unstable, the JaHN-Teller effect is prone to, and the dissolution of manganese in high temperature state is easy to reduce the battery capacity, so its application has also been largely limited.
. Figure / Lithium manganate spinel structure At present, the application range of lithium manganate is important for small batteries, such as mobile phones, digital products, etc., in terms of power lithium batteries, and lithium iron phosphate can be replaced, therefore, there is a strong competition.
Its development direction will be developed toward high energy, high density, low cost trend. Concluding lithium-ion battery products show vigorously developed trends, with the development of science and technology, smartphones, computers, etc., which will make it bigger to change the demand for lithium-ion batteries, which brings great development opportunity.
At the same time, the car lithium ions and the energy storage power supply are also gradually developed, and new rising points are supplied to the lithium ion battery.. It can be seen that in the future, it will strengthen research in this regard, so that the use of lithium-ion batteries will be greater, which will also drive their battery materials to be updated.