Unveiling the Mystery of Internal Resistance in Lithium Batteries: The Secret Behind Key Performance
In the current technological era, lithium batteries, as the power source for numerous electronic devices, have crucial performance. The internal resistance of lithium batteries, a parameter often overlooked, actually has a profound impact on battery performance. Today, let's delve into the mysterious world of lithium battery internal resistance.
I. What is internal resistance? What does it consist of?
The internal resistance of a lithium battery is not just a simple number. It is composed of ohmic internal resistance and polarization internal resistance.
The ohmic internal resistance mainly comes from the electrode materials, electrolyte, diaphragm resistance, and the contact resistance of various parts. This is closely related to the size, structure, and connection method of the battery. For example, different connection methods may lead to differences in contact resistance, thereby affecting the overall internal resistance.
The polarization internal resistance is the resistance caused by the polarization phenomenon during the electrochemical reaction, including electrochemical polarization internal resistance and concentration polarization internal resistance. These two types of polarization internal resistance play a crucial role in the charging and discharging process of the battery.
II. What factors will affect the internal resistance of lithium batteries?
1. Structural design
The number, size, and position of the battery tabs have a direct impact on the battery internal resistance. Imagine that increasing the number of tabs is like opening more channels for the battery, which can effectively reduce the battery internal resistance and allow the current to flow more smoothly.
2. Raw material performance
The positive and negative active materials, conductive agents, coating, rolling, and other processes are all closely related to internal resistance. For example, through ingenious coating and doping processes of the positive electrode material, the electron conduction ability between particles can be significantly improved, thereby reducing internal resistance.
3. Manufacturing process
The preparation process of electrodes and diaphragms, the assembly process of batteries, and the injection process of electrolytes, each step is like "voting" for the size of the battery internal resistance. Fine processes can reduce internal resistance and improve battery performance.
4. Service conditions
Temperature, charge-discharge state, usage time, and the magnitude of the load current also affect internal resistance. In a low-temperature environment, the ionic conductivity of the electrolyte is greatly reduced, resulting in an increase in battery internal resistance. And the battery internal resistance will also change under different charge-discharge states.
III. How to measure the internal resistance of lithium batteries?
1. DC internal resistance measurement method
This is like a "lightning test" for the battery. A short-time pulse is applied to the battery using a current source, and the difference between its terminal voltage and open-circuit voltage is measured. Then, dividing this difference by the test current gives the DC internal resistance of the battery.
2. AC internal resistance measurement method
A small-amplitude AC input is applied to the battery as an excitation, like a gentle "call" to the battery, and then the response of its terminal voltage is monitored. Through a specific program to analyze the data, the AC internal resistance of the battery can be obtained.
IV. What impact does internal resistance have on battery performance?
1. Discharge efficiency
A lower internal resistance is like building a highway for the battery, which can reduce energy losses during the charging and discharging process, increase the output power and efficiency of the battery, and make your electronic devices run longer.
2. Energy density
There is a delicate trade-off relationship between battery internal resistance and energy density. High-energy-density batteries may have higher internal resistance, just like facing some challenges while pursuing powerful power.
3. Cycle life
The increase in battery internal resistance is usually closely related to the battery aging process. Monitoring the change in battery internal resistance is like a "physical examination" for the battery's health status, which is of great significance for predicting battery life and maintaining battery health.
V. The relationship between internal resistance and environmental factors
1. Temperature
Temperature is a key environmental parameter that affects battery internal resistance. In a low-temperature condition, the electrolyte seems to be "frozen", the ionic conductivity is reduced, and the battery internal resistance increases. While at an appropriate temperature, the battery internal resistance will be relatively stable.
2. Charge-discharge cycle
After the battery undergoes multiple charge-discharge cycles, its internal structure may change subtly. These changes are like the marks left by time on the battery and may lead to an increase in battery internal resistance.
In conclusion, the internal resistance of lithium batteries is a complex and mysterious phenomenon. It is affected by multiple factors and has a direct and profound impact on battery performance. Understanding and optimizing battery internal resistance is crucial for improving the overall performance of batteries.
I. What is internal resistance? What does it consist of?
The internal resistance of a lithium battery is not just a simple number. It is composed of ohmic internal resistance and polarization internal resistance.
The ohmic internal resistance mainly comes from the electrode materials, electrolyte, diaphragm resistance, and the contact resistance of various parts. This is closely related to the size, structure, and connection method of the battery. For example, different connection methods may lead to differences in contact resistance, thereby affecting the overall internal resistance.
The polarization internal resistance is the resistance caused by the polarization phenomenon during the electrochemical reaction, including electrochemical polarization internal resistance and concentration polarization internal resistance. These two types of polarization internal resistance play a crucial role in the charging and discharging process of the battery.
II. What factors will affect the internal resistance of lithium batteries?
1. Structural design
The number, size, and position of the battery tabs have a direct impact on the battery internal resistance. Imagine that increasing the number of tabs is like opening more channels for the battery, which can effectively reduce the battery internal resistance and allow the current to flow more smoothly.
2. Raw material performance
The positive and negative active materials, conductive agents, coating, rolling, and other processes are all closely related to internal resistance. For example, through ingenious coating and doping processes of the positive electrode material, the electron conduction ability between particles can be significantly improved, thereby reducing internal resistance.
3. Manufacturing process
The preparation process of electrodes and diaphragms, the assembly process of batteries, and the injection process of electrolytes, each step is like "voting" for the size of the battery internal resistance. Fine processes can reduce internal resistance and improve battery performance.
4. Service conditions
Temperature, charge-discharge state, usage time, and the magnitude of the load current also affect internal resistance. In a low-temperature environment, the ionic conductivity of the electrolyte is greatly reduced, resulting in an increase in battery internal resistance. And the battery internal resistance will also change under different charge-discharge states.
III. How to measure the internal resistance of lithium batteries?
1. DC internal resistance measurement method
This is like a "lightning test" for the battery. A short-time pulse is applied to the battery using a current source, and the difference between its terminal voltage and open-circuit voltage is measured. Then, dividing this difference by the test current gives the DC internal resistance of the battery.
2. AC internal resistance measurement method
A small-amplitude AC input is applied to the battery as an excitation, like a gentle "call" to the battery, and then the response of its terminal voltage is monitored. Through a specific program to analyze the data, the AC internal resistance of the battery can be obtained.
IV. What impact does internal resistance have on battery performance?
1. Discharge efficiency
A lower internal resistance is like building a highway for the battery, which can reduce energy losses during the charging and discharging process, increase the output power and efficiency of the battery, and make your electronic devices run longer.
2. Energy density
There is a delicate trade-off relationship between battery internal resistance and energy density. High-energy-density batteries may have higher internal resistance, just like facing some challenges while pursuing powerful power.
3. Cycle life
The increase in battery internal resistance is usually closely related to the battery aging process. Monitoring the change in battery internal resistance is like a "physical examination" for the battery's health status, which is of great significance for predicting battery life and maintaining battery health.
V. The relationship between internal resistance and environmental factors
1. Temperature
Temperature is a key environmental parameter that affects battery internal resistance. In a low-temperature condition, the electrolyte seems to be "frozen", the ionic conductivity is reduced, and the battery internal resistance increases. While at an appropriate temperature, the battery internal resistance will be relatively stable.
2. Charge-discharge cycle
After the battery undergoes multiple charge-discharge cycles, its internal structure may change subtly. These changes are like the marks left by time on the battery and may lead to an increase in battery internal resistance.
In conclusion, the internal resistance of lithium batteries is a complex and mysterious phenomenon. It is affected by multiple factors and has a direct and profound impact on battery performance. Understanding and optimizing battery internal resistance is crucial for improving the overall performance of batteries.
