You become half an expert on lithium-ion batteries after 30 minutes

Because more and more people need to understand the energy storage industry, and batteries are at the core of energy storage, Light technology has sorted out the relevant information, sorted out a simple information for everyone. 18650 manufacture Hopefully after reading, you will become a half expert about batteries and will form a more professional knowledge framework.

The first is the battery family

Lithium batteries were originally known as lithium metal batteries, but they are no longer used in China due to their explosive nature. Lithium battery companies today use lithium ion batteries.

The number 7 and 5 batteries we use are dry batteries, the nickel metal hydride batteries were used in the early days of brick phones, the lead-acid batteries used in wheelbarrows, four squares stacked on top of each other, and most of the batteries we use in our phones, laptops, and even electric cars are lithium-ion batteries.

An analysis of the characteristics of the main electrochemical batteries used for energy storage

The second step is to analyze battery terminology

SOX: Full name is state X, battery state description, H is health, C is capacity, P is power, E is energy. It's kind of like engine parameters, displacement, power, energy, run time, etc.

Like water in a bucket, SOC (state of charge) refers to the charge of a battery. SOC is the amount of electricity available in the battery at a given time. A battery's SOC is zero when discharged and one when fully charged. Actual capacity / available capacity.

DOD: (Depth of Discharge) refers to the depth of discharge of the battery, the battery in the case of full DOD is 0, completely different discharge treatment of the DOD is 1, so the normal situation below the DOD through the battery is a problem between 0 and 1 value. DOD + SOC = 1.

As a battery ages, its capacity (or initial capacity rating) decreases, usually in terms of capacity and internal resistance.

It is generally accepted that SOH is defined as battery capacity decay, and the definition is as follows:

Current battery capacity is cage type; rated battery capacity is cage type.

The third aspect is the classification of lithium batteries

Based on practical performance, it can be divided into power types (sprints, short-term high-power output) and energy types (long-distance running, high energy storage).

In terms of appearance, they are cylindrical, square (steel/aluminum shell), and soft (aluminum-plastic film).

Liquid lithium-ion batteries (Lib) and polymer lithium-ion batteries (PLB) are pressed electrolyte materials.

Liquid lithium-ion batteries use liquid electrolytes (as most batteries today do). Solid polymer electrolytes, also known as polymer gel electrolytes, are replacing liquid lithium-ion batteries with solid polymer electrolytes. Solid-state batteries have solid electrodes and electrolytes.

A lithium iron phosphate battery (LFP), a lithium cobalt oxide battery (LCO), a lithium manganate battery (LMO), (binary battery: lithium nickel manganate / u 002 Li-rich nickel cobalt), (ternary battery: lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminate battery (NCA).

Battery materials include lithium titanate (LTO), graphene, and nanocomposite carbon fiber.

Battery type 18650

18650 batteries are lithium-ion batteries, similar to dry batteries 7, 5, 1, etc.

18650, the original lithium-ion battery, was developed by Japan's SONY company to reduce costs. As the name suggests, this cylindrical battery has a diameter of 18mm and a length of 65mm. The standard model was created for convenience and is widely used in both lithium-ion and lithium iron phosphate batteries. The nominal voltage for lithium-ion batteries is 3.7v with a charging cutoff at 4.2v, while the capacity ranges from 1200mAh to 3350mAh. On the other hand, the nominal voltage for lithium iron phosphate batteries is 3.2V and the charging cut-off voltage is 3.6v, with common capacities falling between 2200mAh and 2600mAh.

18650 has the following advantages:

Japanese manufacturers have established a high level of consistency with the 18650 battery, the oldest, most mature, and most stable lithium-ion battery.

When it comes to safety, 18650 batteries have a steel housing that minimizes the risk of collisions. Over time, the production process for these batteries has also greatly improved, further enhancing their safety. Although steel shell lithium batteries were once known to be prone to explosions, the latest 18650 battery models now include a safety valve. This valve serves a dual purpose – it releases built up internal pressure and physically separates the battery from its surroundings. This effectively isolates the battery and ensures that other batteries in the pack remain safe.

Although polymer lithium batteries are relatively safe compared to other batteries, they also have high energy density, low packaging film strength, no explosion, and combustion is the worst environment. In addition to providing customized product designs, it also increases R&D and production costs for the enterprise, reducing its universality.

Battery made of lithium iron phosphate

Lithium iron phosphate, with the molecular formula LiFePO4 and abbreviated as LFP, is a popular cathode material for lithium-ion batteries. This type of battery is also referred to as a lithium iron phosphate battery due to its composition. Unlike other batteries, it does not contain costly elements like cobalt and has a lower raw material cost. The earth's abundance of phosphorus, lithium, and iron ensures there are no supply issues in obtaining this material. With a moderate operating voltage (3.2V), high capacitance (170mAh/g), and excellent discharge power, this battery charges quickly and has a long cycle life. Additionally, it boasts high stability in both high temperature and thermal environments.

The fourth factor is the voltage and capacity of lithium batteries

Lithium-ion batteries' voltage varies with discharge current, ambient temperature, and cathode and anode materials.

During the charging and discharging process, the voltage undergoes continuous fluctuations. For instance, when using 490mA as a reference point, the open circuit voltage at full charge is 4.2V. As the battery is discharged, the voltage gradually decreases on the vertical axis while the discharge increases on the horizontal axis. At approximately 3.5V, the voltage drops sharply. However, to simplify matters, only the average of 3.7V on the gently sloping part of the curve is identified as the battery voltage. This is also known as the nominal voltage.

As discharge current and temperature increase, the voltage will decrease under low current and room temperature operating conditions.

A significant element that impacts battery voltage is the composition of the positive and negative materials. Panasonic batteries, for instance, utilize lithium cobalt oxide and graphite as their standard materials, which have been widely used in the lithium battery industry for several years. However, recent advancements in battery technology have resulted in the emergence of 3.6V or 3.8V lithium batteries with alternative cathode materials. These new materials provide increased energy density compared to lithium-cobalt batteries, allowing for greater energy storage per unit weight and volume.

There are two types of battery capacity: rated capacity and actual capacity.

Under certain discharge conditions, the actual capacity of the battery is lower than the theoretical capacity.

The rated capacity refers to the minimum amount of electricity a battery should discharge under certain discharge conditions.

The battery system's capacity is typically measured in AH, and we label it as mAh on the individual battery for ease of use. For instance, if the battery has a rated capacity of 1300mAh, it can discharge 130mA of current and work for 10 hours (1300mAh/130mA=10h). This represents an optimal scenario for analysis and management of digital electronic equipment in our society, but in real-life teaching or enterprise settings, the current may not always remain constant at a specific value.

Generally, 18650 lithium batteries have a capacity between 1200mAh and 3600mAh.

High school taught us that mAh is a unit of electricity, which you multiply by a voltage to get a unit of energy.

Method for calculating battery capacity:

Method for calculating battery energy:

How can a phone's energy consumption be measured in one unit of battery life? This is due to the use of highly dense material, lithium cobalt, in the cathodes of lithium-ion batteries used in portable electronic devices like cell phones. As the same material is also used for the positive electrode of the phone's battery, its voltage is typically close to 3.7V (depending on the manufacturer's process). Additionally, most phones only have one battery (although some recent models may have two Mach 2000 batteries), making it possible to simply measure the energy stored by its capacity.

The computer's battery reflects both its capacity and energy levels. This is due to the presence of multiple batteries within the battery pack, connected in series and parallel. Therefore, measuring solely based on the capacity of one battery is not accurate. As we know from basic high school knowledge, connecting batteries in parallel increases the capacity but not the voltage, while connecting them in series increases the voltage but not the capacity.

energy storage industry professional knowledge framework

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