Lithium - ion Batteries: Breaking through the Limits of Energy and SpeedLithium - Ion Battery Equipment
In this era of rapid technological development, lithium - ion batteries, as the core power sources for numerous electronic devices and electric vehicles, are crucial in terms of performance. And the energy density and charge - discharge rate of lithium - ion batteries are two key indicators that determine their performance.（Lithium - Ion Battery Equipment）
I. Energy Density: The Bottleneck Restricting the Development of Lithium - ion Batteries
Energy density, simply put, is the amount of energy that can be stored per unit volume or weight. A higher energy density means that the battery can provide longer - lasting endurance for devices. From lead - acid batteries to nickel - cadmium batteries, nickel - metal hydride batteries, and then to lithium - ion batteries, the energy density has been continuously increasing. However, compared to human energy requirements and the development speed of the industrial scale, this increase seems rather slow. Some people even joke that human progress is "stuck" with batteries.
In lithium - ion batteries, lithium is mainly the carrier of electrical energy, and other substances limit the increase in energy density to a certain extent. For example, in a lithium - ion battery, the mass proportion of lithium is usually just over 1%, and the remaining 99% of the components are substances that do not perform the energy - storage function.
(2) Methods to Increase Energy Density
Increase the Proportion of Positive - electrode Active Substances: In the same battery chemical system, increasing the content of lithium can increase the energy density. Therefore, under certain volume and weight limitations, increasing the proportion of positive - electrode active substances allows more lithium to participate in energy storage.
Increase the Proportion of Negative - electrode Active Substances: To match the increase in positive - electrode active substances, more negative - electrode active substances are required to accommodate the lithium ions migrating from the positive electrode, preventing irreversible chemical reactions and battery capacity attenuation.
Increase the Specific Capacity of Positive - electrode Materials: When the total amount of positive - electrode active substances is fixed, increasing the mass proportion of lithium ions that can be inserted and extracted relative to the positive - electrode active substances, that is, increasing the specific capacity, can increase the energy density. From lithium cobaltate to lithium iron phosphate, and then to ternary materials, all are to achieve this goal. To further improve, new positive - electrode materials need to be researched and industrialized.
Increase the Specific Capacity of Negative - electrode Materials: Although the specific capacity of negative - electrode materials is not currently the main bottleneck for the energy density of lithium - ion batteries, increasing the specific capacity of the negative electrode can reduce the mass of negative - electrode materials, accommodate more lithium ions, and thus increase the energy density. For example, researching hard - carbon materials, nano - carbon materials, tin - based and silicon - based negative - electrode materials, etc.
Weight Reduction: Besides positive - and negative - electrode active substances, electrolytes, separators, binders, conductive agents, current collectors, substrates, and housing materials account for about 40% of the total battery weight. Reducing the weight of these materials without affecting battery performance can increase the energy density of lithium - ion batteries.
Increasing the energy density of lithium - ion batteries is a systematic project. Solutions in the short - term, medium - term, and long - term need to be sought from aspects such as improving manufacturing processes, enhancing the performance of existing materials, and developing new materials and new chemical systems.
II. Charge - Discharge Rate: The Key to Determining Battery Speed
The charge - discharge rate determines the speed at which lithium - ion batteries store and release energy. In power tools and electric vehicles, the charge - discharge rate is particularly important.
Currently, lithium - ion batteries take a long time to charge, and they cannot be discharged too rapidly, otherwise the battery life and safety will be affected. For example, when driving an electric vehicle to run errands, if the battery runs out halfway and you go to charge it, it may take a long time to fully charge; when climbing a slope, the vehicle may lack power due to insufficient discharge rate. These are scenarios we do not want to see, but they are the current situation of lithium - ion batteries.
The intercalation and de - intercalation rates of lithium ions inside the positive/negative - electrode active substances, as well as the migration speed between the positive and negative electrodes, are important factors affecting the charge - discharge rate. To increase the lithium - ion diffusion ability, the following aspects can be considered:
Optimization of Positive - electrode Materials: The positive - electrode plate should be thin, and the compaction density of the positive - electrode material should be increased to shorten the "racing distance" of lithium ions. At the same time, there should be enough pores inside the active substance to provide a uniformly distributed "runway" for lithium ions. However, these two points are contradictory, and a balance needs to be found. In addition, selecting a positive - electrode material with a high lithium - ion diffusion coefficient can also improve the rate performance.
Improvement of Negative - electrode Materials: The treatment idea for negative - electrode materials is similar to that of positive - electrode materials. Starting from aspects such as structure, size, and thickness, the concentration difference of lithium ions in the negative - electrode materials can be reduced to improve the diffusion ability. For example, researching nano - carbon materials can improve the specific surface area, internal structure, and diffusion channels of negative - electrode materials, thereby enhancing the rate performance.
(2) Increase the Ionic Conductivity of the Electrolyte
In the "swimming race" of lithium ions in the electrolyte, reducing the resistance of the electrolyte (increasing the ionic conductivity) is the key to increasing the speed. Currently, the organic electrolytes used in lithium - ion batteries have low ionic conductivity, and the resistance becomes an important part of the battery resistance. In addition, attention should also be paid to the chemical stability and thermal stability of the electrolyte. An electrolyte with high lithium - ion conduction ability, good chemical stability and thermal stability, and compatibility with electrode materials should be selected.
(3) Reduce the Internal Resistance of the Battery
The internal resistance of the battery is composed of the internal resistance of the positive - electrode active substance, the resistances of the positive and negative - electrode current collectors, the resistances at the electrolyte - electrode interfaces, etc. The internal resistance of the battery can be reduced and the rate performance can be improved by adding conductive agents inside the positive - electrode active substance, changing the material and size of the current collectors, optimizing the wetting degree between the electrolyte and the electrodes, and controlling the changes of the SEI film on the negative - electrode surface.
In conclusion, the energy density and charge - discharge rate of lithium - ion batteries are key indicators of their performance. To break through these limitations, researchers need to conduct in - depth research and innovation from multiple aspects, opening up new paths for the development of lithium - ion batteries to meet people's demands for high - performance batteries.
The new laser etching machine developed by Yixin Feng has made certain achievements in this regard. The equipment adopts laser physical scribing technology to directly etch vertical channels on the negative electrode. This technology can provide the most effective capillary transmission, significantly enhancing the wetting effect and speed of the electrolyte. At the same time, it can reduce the tortuosity of the electrode pores, increase the effective lithium - ion diffusion coefficient, and store the electrolyte by forming grooves. In this way, the cycle retention rate of the battery can be increased, the internal resistance of the battery can be reduced, and the lithium plating on the negative electrode can be reduced.
I. Energy Density: The Bottleneck Restricting the Development of Lithium - ion Batteries
Energy density, simply put, is the amount of energy that can be stored per unit volume or weight. A higher energy density means that the battery can provide longer - lasting endurance for devices. From lead - acid batteries to nickel - cadmium batteries, nickel - metal hydride batteries, and then to lithium - ion batteries, the energy density has been continuously increasing. However, compared to human energy requirements and the development speed of the industrial scale, this increase seems rather slow. Some people even joke that human progress is "stuck" with batteries.
- Factors Affecting the Energy Density of Lithium - ion Batteries
In lithium - ion batteries, lithium is mainly the carrier of electrical energy, and other substances limit the increase in energy density to a certain extent. For example, in a lithium - ion battery, the mass proportion of lithium is usually just over 1%, and the remaining 99% of the components are substances that do not perform the energy - storage function.
(2) Methods to Increase Energy Density
Increase the Proportion of Positive - electrode Active Substances: In the same battery chemical system, increasing the content of lithium can increase the energy density. Therefore, under certain volume and weight limitations, increasing the proportion of positive - electrode active substances allows more lithium to participate in energy storage.
Increase the Proportion of Negative - electrode Active Substances: To match the increase in positive - electrode active substances, more negative - electrode active substances are required to accommodate the lithium ions migrating from the positive electrode, preventing irreversible chemical reactions and battery capacity attenuation.
Increase the Specific Capacity of Positive - electrode Materials: When the total amount of positive - electrode active substances is fixed, increasing the mass proportion of lithium ions that can be inserted and extracted relative to the positive - electrode active substances, that is, increasing the specific capacity, can increase the energy density. From lithium cobaltate to lithium iron phosphate, and then to ternary materials, all are to achieve this goal. To further improve, new positive - electrode materials need to be researched and industrialized.
Increase the Specific Capacity of Negative - electrode Materials: Although the specific capacity of negative - electrode materials is not currently the main bottleneck for the energy density of lithium - ion batteries, increasing the specific capacity of the negative electrode can reduce the mass of negative - electrode materials, accommodate more lithium ions, and thus increase the energy density. For example, researching hard - carbon materials, nano - carbon materials, tin - based and silicon - based negative - electrode materials, etc.
Weight Reduction: Besides positive - and negative - electrode active substances, electrolytes, separators, binders, conductive agents, current collectors, substrates, and housing materials account for about 40% of the total battery weight. Reducing the weight of these materials without affecting battery performance can increase the energy density of lithium - ion batteries.
Increasing the energy density of lithium - ion batteries is a systematic project. Solutions in the short - term, medium - term, and long - term need to be sought from aspects such as improving manufacturing processes, enhancing the performance of existing materials, and developing new materials and new chemical systems.
II. Charge - Discharge Rate: The Key to Determining Battery Speed
The charge - discharge rate determines the speed at which lithium - ion batteries store and release energy. In power tools and electric vehicles, the charge - discharge rate is particularly important.
- Current Situation and Problems of the Charge - Discharge Rate of Lithium - ion Batteries
Currently, lithium - ion batteries take a long time to charge, and they cannot be discharged too rapidly, otherwise the battery life and safety will be affected. For example, when driving an electric vehicle to run errands, if the battery runs out halfway and you go to charge it, it may take a long time to fully charge; when climbing a slope, the vehicle may lack power due to insufficient discharge rate. These are scenarios we do not want to see, but they are the current situation of lithium - ion batteries.
- Factors Affecting the Charge - Discharge Rate of Lithium - ion Batteries and Improvement Methods
The intercalation and de - intercalation rates of lithium ions inside the positive/negative - electrode active substances, as well as the migration speed between the positive and negative electrodes, are important factors affecting the charge - discharge rate. To increase the lithium - ion diffusion ability, the following aspects can be considered:
Optimization of Positive - electrode Materials: The positive - electrode plate should be thin, and the compaction density of the positive - electrode material should be increased to shorten the "racing distance" of lithium ions. At the same time, there should be enough pores inside the active substance to provide a uniformly distributed "runway" for lithium ions. However, these two points are contradictory, and a balance needs to be found. In addition, selecting a positive - electrode material with a high lithium - ion diffusion coefficient can also improve the rate performance.
Improvement of Negative - electrode Materials: The treatment idea for negative - electrode materials is similar to that of positive - electrode materials. Starting from aspects such as structure, size, and thickness, the concentration difference of lithium ions in the negative - electrode materials can be reduced to improve the diffusion ability. For example, researching nano - carbon materials can improve the specific surface area, internal structure, and diffusion channels of negative - electrode materials, thereby enhancing the rate performance.
(2) Increase the Ionic Conductivity of the Electrolyte
In the "swimming race" of lithium ions in the electrolyte, reducing the resistance of the electrolyte (increasing the ionic conductivity) is the key to increasing the speed. Currently, the organic electrolytes used in lithium - ion batteries have low ionic conductivity, and the resistance becomes an important part of the battery resistance. In addition, attention should also be paid to the chemical stability and thermal stability of the electrolyte. An electrolyte with high lithium - ion conduction ability, good chemical stability and thermal stability, and compatibility with electrode materials should be selected.
(3) Reduce the Internal Resistance of the Battery
The internal resistance of the battery is composed of the internal resistance of the positive - electrode active substance, the resistances of the positive and negative - electrode current collectors, the resistances at the electrolyte - electrode interfaces, etc. The internal resistance of the battery can be reduced and the rate performance can be improved by adding conductive agents inside the positive - electrode active substance, changing the material and size of the current collectors, optimizing the wetting degree between the electrolyte and the electrodes, and controlling the changes of the SEI film on the negative - electrode surface.
In conclusion, the energy density and charge - discharge rate of lithium - ion batteries are key indicators of their performance. To break through these limitations, researchers need to conduct in - depth research and innovation from multiple aspects, opening up new paths for the development of lithium - ion batteries to meet people's demands for high - performance batteries.
The new laser etching machine developed by Yixin Feng has made certain achievements in this regard. The equipment adopts laser physical scribing technology to directly etch vertical channels on the negative electrode. This technology can provide the most effective capillary transmission, significantly enhancing the wetting effect and speed of the electrolyte. At the same time, it can reduce the tortuosity of the electrode pores, increase the effective lithium - ion diffusion coefficient, and store the electrolyte by forming grooves. In this way, the cycle retention rate of the battery can be increased, the internal resistance of the battery can be reduced, and the lithium plating on the negative electrode can be reduced.
