Laminated aluminum plastic film: It is a key material for packaging lithium battery cells in flexible packaging. It is a high-strength, high barrier multi-layer composite material composed of various plastics, aluminum foils, and adhesives. It has extremely high barrier properties, electrolyte stability, cold stamping formability, puncture resistance, and insulation, making it the most critical safety link in soft pack lithium batteries.
Plate: The two electrodes of a chemical power source, consisting of an active material and a supporting and conductive "collector", generally a sheet-like porous body. When making electrode plates, it is often not necessary to directly add the active substance to the current collector, but to use specific processes to make the raw materials into specific forms and then combine them with the current collector. For example, in lead-acid batteries, common forms of electrode plates include pasted plates and tubular plates.
Positive plate: It is the electrode plate in a battery with a relatively positive electrode potential. During the charging and discharging process of the battery, the active material on the positive plate participates in electrochemical reactions, storing and releasing electrical energy. At the same time, the positive electrode plate is also an important part of connecting the external circuit of the battery, ensuring that the current can pass smoothly.
Negative plate: It is the electrode plate with a relatively negative electrode potential in a battery, and together with the positive plate, it forms the basic structure of the battery. During the discharge process of the battery, the active material on the negative electrode plate undergoes oxidation reaction, releasing electrons and flowing through the external circuit to the positive electrode plate, thereby generating current. During the charging process, the negative electrode plate receives electrons flowing back from the positive electrode plate, causing the active material to undergo a reduction reaction and return to its original state.
Electrode: It is used as the two ends for inputting or exporting current in a conductive medium (solid, gas, vacuum, or electrolyte solution). The pole that inputs current is called the anode or positive pole, and the pole that releases current is called the cathode or negative pole. The function of electrodes is to act as a conductive medium for current, carrying and converting electrical energy in circuits, including providing electron flow paths, realizing electrochemical reactions, and converting signals.
The active surface of an electrode: refers to a specific area in the electrode material that comes into contact with an electrolyte solution and can participate in electrochemical reactions. These regions typically possess unique physical and chemical properties, such as high specific surface area, high conductivity, and abundant catalytic active sites. The main functions are to provide charge transfer channels, catalyze electrochemical reactions, and increase reaction area.
Electrolyte: A compound that is soluble in aqueous solution or can conduct electricity on its own in a molten state. According to their ionization degree, electrolytes can be divided into strong electrolytes and weak electrolytes, with almost all ionized electrolytes being strong electrolytes and only a small portion ionized electrolytes being weak electrolytes. Electrolytes are substances that are bound by ionic or polar covalent bonds, and can dissociate into freely moving ions when dissolved in water or heated, thereby conducting electricity.
Separator: Is a thin film material located between the positive and negative electrodes of a battery, which has a direct impact on the safety and cost of the battery. The main functions are to isolate positive and negative electrodes, allow ions to pass through, improve safety, regulate battery internal pressure, and control battery capacity.
Leakage: It is the phenomenon of electric fluid, gas, or other substances overflowing from the inside of a battery. This leakage may be caused by various reasons, including but not limited to sealing issues, safety valve failures, terminal leaks, etc.
Active material: refers to substances that can participate in chemical reactions during battery charging and discharging processes, storing and releasing electrical energy through oxidation and reduction reactions.
Electrochemical reaction: refers to a chemical reaction that occurs in an electrolyte solution due to the action of an electric current. It belongs to the category of electrochemistry and is a branch of chemistry that deals with the relationship between electricity and chemical changes. Electrochemical reactions can be divided into two categories: electrolytic reactions and battery reactions.
Electrode polarization: refers to the phenomenon where the electrode potential deviates from the reversible electrode potential when a current passes through the electrode. This deviation is caused by the slow speed of a certain step in the electrode reaction process, resulting in the electrode potential deviating from its equilibrium state.
Concentration polarization: refers to the phenomenon in which the concentration of solutes (ions or solutes with different molecular weights) changes at the interface or boundary layer during separation processes (such as membrane separation) or electrolysis, resulting in an increase in fluid resistance and local osmotic pressure, which in turn affects the solvent permeation flux or electrode potential.
Ohmic polarization: refers to the process in which positive and negative ions within a material are redistributed and redirected under the influence of an electric field, resulting in the overall polarization of the material. It can also be referred to as resistance polarization, which is a phenomenon that occurs in electrochemical systems due to the resistance of electrolytes to the flow of current.
Activation polarization: Also known as electrochemical polarization or chemical polarization, is a fundamental form of electrode polarization. It refers to the phenomenon where the potential of an electrode deviates from the equilibrium potential due to delayed electrochemical reactions.
Anodic polarization: It is a phenomenon in electrochemical processes where the anodic potential deviates from its equilibrium potential and moves in a positive direction due to the action of an external current. Principle: In an electrochemical system, when an external current passes through the anode, the original equilibrium state is broken, and an oxidation reaction occurs on the anode surface, causing electrons to flow out of the anode and enter the external circuit. Due to the electron outflow velocity being greater than the velocity of metal ions entering the solution on the anode surface, positive charges accumulate on the anode surface, causing the anode potential to move in the positive direction.
Cathodic polarization: The phenomenon in which the cathode potential in a primary battery or electrolytic cell moves in the negative direction after passing current. Principle: In an electrochemical system, when an external current passes through the cathode, a reduction reaction occurs on the cathode surface, and electrons flow into the cathode from the external circuit. If the cathodic reaction is not yet able to absorb these electrons, the electrons will accumulate at the cathode, causing the potential in the cathode region to deviate from the equilibrium potential and change in the negative direction, thus forming cathodic polarization.
Side reaction: refers to additional and unnecessary reactions that occur during the operation of a battery, in addition to the main battery reactions. These reactions can have adverse effects on the performance of the battery, such as reducing charging efficiency, decreasing battery capacity, shortening battery life, or leading to a decline in battery performance.
Capacity: Refers to the amount of electricity that a battery can release under certain conditions (such as discharge rate, temperature, termination voltage, etc.), usually measured in ampere hours (A · h) or milliampere hours (mAh). Among them, 1A · h is equal to 3600 coulombs (C), and 1Ah is equal to 1000mAh.
Voltage: A physical quantity that measures the uniformity of charge distribution within a battery, representing the potential difference between the positive and negative electrodes of the battery. Simply put, battery voltage is the "pressure" inside the battery, which causes electrons to flow from the positive electrode to the negative electrode through an external circuit, thereby generating current.
Current: A physical quantity that describes the rate of charge flow in a battery, reflecting the amount of current that the battery can provide under specific conditions such as discharge rate, temperature, load, etc.
Resistance: refers to the resistance that a battery experiences when current flows through its interior during operation. It is an important technical indicator for measuring battery performance. The internal resistance of batteries mainly includes ohmic resistance and polarization resistance, among which polarization resistance includes electrochemical polarization resistance and concentration polarization resistance.
Rated capacity: refers to the time that a battery can continuously supply current under specific load conditions when fully charged, or expressed in physical units as a measure of the amount of electricity that the battery can store and release.
Residual capacity: refers to the amount of electricity that a battery can store and release in its current state, that is, the total amount of electricity that the battery can provide from its current state to complete discharge. This indicator is crucial for evaluating the battery's usage status, predicting remaining usage time, and ensuring proper device operation.
Volumetric capacity: refers to the amount of electrical energy that a battery or active substance can store and release per unit volume. It is usually expressed in milliampere hours per milliliter (mAh/mL) or milliampere hours per cubic centimeter (mAh/cm ³), reflecting the energy density of the battery in terms of volume.
Gravimetric capacity: also known as weight specific capacity, refers to the amount of electricity that a unit mass of battery or active material can provide when fully discharged. It is usually expressed in milliampere hours per gram (mAh/g) or watt hours per kilogram (Wh/kg), reflecting the energy density of the battery in terms of mass.
Area specific capacity: refers to the amount of energy that a battery can provide per unit area (such as the surface area of an electrode), reflecting the energy density of the battery in the area dimension. This indicator is usually expressed in mAh/cm ² or F/cm ² (for capacitive energy storage devices).
Capacity per gram: also known as capacity density or mass specific capacity, typically expressed in milliampere hours per gram (mAh/g). It reflects the amount of electricity that can be stored and released per unit mass of active substance, and is one of the important parameters for measuring the energy storage capacity of a battery.
Temperature coefficient: refers to the ratio of the change in battery output voltage with temperature, usually expressed as the change in voltage per degree Celsius (such as mV/℃ or V/K). Meaning: It reflects the ability of the battery to maintain stable output voltage under different temperature conditions. The smaller the temperature coefficient, the lower the sensitivity of the battery to temperature changes and the more stable the output voltage.
Battery energy: refers to the total amount of electrical energy stored in a battery, representing the amount of energy that the battery can release under certain conditions. It is expressed in watt hours (Wh), which is the product of the rated voltage, operating current, and operating time of the battery.
Volumetric energy: also known as "volumetric energy density", refers to the amount of energy that a battery can provide per unit volume. It reflects the energy density of the battery in the volume dimension.
Gravimetric energy: also known as mass energy density, is a physical quantity that describes the energy output per unit mass of a battery. It is one of the important indicators for evaluating the performance of batteries, and has a significant impact on the overall quality and driving range of electric vehicles.
Volumetric power: also known as "volumetric power density", refers to the ratio of the power output of a battery to its volume, and is one of the important indicators for evaluating the performance of a battery.
Cycling life: refers to the number of full charge and full discharge cycles that a battery can withstand before its capacity drops to a specified value (such as 80% of its initial capacity) under a certain charging and discharging regime.
Charge/discharge curve: It is a graphical representation that describes the voltage variation of a battery over time or capacity during the charging and discharging process. These curves are of great significance for evaluating battery performance, optimizing battery usage, and predicting battery life.
Discharge current: The current formed when a battery or battery releases stored electrical energy to a load. It is an important indicator of battery performance, directly affecting the battery's usage time and efficiency.
Discharge rate: refers to the speed at which the voltage of a battery decreases from its initial value to its final value during the discharge process, or can be understood as the current value required for the battery to discharge its rated capacity within a specified time. It is an important indicator for measuring the discharge performance of batteries.
Over discharge: refers to the behavior of a battery continuing to discharge after the voltage drops below the specified termination voltage during discharge. During the discharge process of the battery, the stored electrical energy is gradually released and the voltage slowly drops. When the voltage drops to a certain specified value, discharge should be stopped and the battery should be recharged to restore its energy storage state. If the discharge continues below this specified value, it is considered excessive discharge.
Short circuit: It is caused by some reason that the positive and negative poles of the battery are connected to each other with very low resistance, forming an abnormal path. According to Ohm's law (I=U/R), under a constant voltage U, the smaller the resistance R, the larger the current I. Therefore, when the battery is short circuited, a very large current will be generated. Meanwhile, according to Joule's law (Q=I ² Rt), when a large current passes through a conductor, a significant amount of heat is generated, leading to a sharp increase in battery temperature.
Short circuit current: refers to the current passing through the short-circuit path when a battery experiences a short circuit. This type of current is usually very large and may far exceed the rated current of the battery, causing serious damage to the battery and surrounding equipment, and even potentially causing fires or explosions.
Self discharge: It is a phenomenon in which the battery's power gradually decreases in unused or stored state due to various internal factors such as side reactions of the electrolyte, instability of electrode materials, physical micro short circuits, membrane defects, environmental temperature, storage status, etc. For lithium-ion batteries, self discharge is mainly caused by chemical reactions inside the battery, such as the migration of lithium ions in the electrolyte and the redox reactions of electrode materials.
Depth of discharge: It is an important indicator for measuring the usage status of a battery, reflecting the ratio of the used capacity to the total capacity of the battery. This ratio is usually expressed in percentage form, and the specific calculation method is: DOD=(1- current remaining power/total battery power) x 100%.
Discharge rate/charge rate: refers to the current value required for a battery to discharge or charge its rated capacity within a specified time, usually represented by the letter C. Numerically, it is equal to the ratio of charge and discharge current to rated capacity, i.e. C=I/Q, where I represents charge and discharge current (in ampere hours) and Q represents the rated capacity of the battery (in ampere hours).
Discharge voltage: It is the potential difference between the two electrodes of a battery when it passes through an external circuit during the discharge process. It is always lower than the open circuit voltage of the battery because the current must overcome the internal resistance of the battery when passing through it. The magnitude of the discharge voltage is related to factors such as the type, capacity, discharge current, and discharge time of the battery.
End of discharge voltage: It is an important parameter during the battery discharge process, marking the end point of battery discharge. When the battery voltage drops below the termination voltage, continuing to discharge may cause irreversible damage to the battery, such as decreased capacity, shortened lifespan, or even damage. Therefore, reasonable control of the termination voltage of the battery is of great significance for protecting the battery and extending its service life.
Nominal voltage: refers to the average output voltage value of a battery from the beginning to the end of discharge when it is fully charged. It reflects the rated operating voltage range of the battery, providing important reference for the application, charging, protection, and other aspects of the battery.
Open circuit voltage: equal to the difference between the positive electrode potential and the negative electrode potential of a battery when there is no current passing through the two poles during an open circuit. In actual battery systems, since the potential established at the two poles of the battery is mostly a stable potential, the open circuit voltage is actually the difference between the stable potentials of the two poles. The open circuit voltage is generally lower than the electromotive force of the battery, but it can be approximated as the electromotive force of the battery.
Working voltage: refers to the actual voltage value provided by the battery during the discharge process. Due to the internal resistance of the battery, when current flows through the battery, it must overcome the resistance of the internal resistance. Therefore, the operating voltage is always lower than the open circuit voltage of the battery (i.e. the voltage when the battery is not connected to any load or external circuit).
Shell voltage: The shell voltage of a battery is not a standard parameter of the battery, but in some cases, such as fault diagnosis or performance evaluation, the voltage between the battery shell and the electrodes is measured. This voltage value can reflect the internal state of the battery, such as internal resistance, electrolyte condition, and the presence of short circuits.