What is the energy density of lithium ion battery

Introduce

What determines the cruising range of new energy vehicles? The endurance of new energy vehicles mainly depends on the available power and energy consumption of the vehicle. When the same energy consumption remains unchanged, and the volume and weight of the battery pack remain unchanged, the single maximum driving range of a new energy vehicle mainly depends on the energy density of lithium-ion batteries.

Endurance ↑ = available power ↑ ÷ energy consumption ↓

What is energy density of lithium ion battery?

Energy density refers to the amount of energy stored in a unit of a certain space or mass matter. Lithium batteries’ energy density is the average per unit volume or quality release of electricity. Lithium battery energy density is usually divided into two dimensions: weight energy density and bulk density.

Lithium battery energy density weight = x discharge battery capacity/weight platform, the basic unit for Wh/kg (w/kg)

Cell volume energy density = battery capacity by discharge platform/volume, the basic unit for Wh/L (w/L)

The greater the energy density of a lithium battery, the unit volume or weight the more electricity storage.

What is the Lithium battery energy density of the monomer?

The energy density of lithium-ion batteries usually refers to two different concepts, one is single lithium battery energy density, and another is the energy density of the battery system.

The battery cell is the smallest unit of a battery system. M a battery of a module, a battery pack N modules. This is the basic structure of a vehicle’s power battery.

As the name implies, the energy density of a single cell is the energy density of the single cell level.

What is the system energy density?

After completion of the system energy density refers to the monomer composition, weight, or volume of the battery system and the comparison of the weight or volume of the whole battery system. Because the battery system contains a battery management system, the thermal management system, high and low voltage circuits, etc., occupying some of the weight of the battery system and internal space, the energy density of the battery system is lower than the energy density of the monomer.

Energy density = power battery ➗ battery system weight or volume battery system

What limits the energy density of lithium ion battery?

The chemical system is the main reason behind the battery.

In general, the four parts of lithium-ion batteries are critical: the anode, cathode, electrolyte, and diaphragm. The positive and negative poles are the places where chemical reactions take place, which is equivalent to the two veins of Ren and Du, and their important status can be seen.

As we all know, the ternary lithium battery pack for the positive system of energy density is higher than that of the anode for lithium iron phosphate battery energy density of the system. Why is this?

At present most of the lithium-ion battery anode materials for graphite, graphite theory g capacity is 372 mah/g. The theory of positive electrode material of lithium iron phosphate capacity is 160 mah/g only, and the ternary material nickel cobalt manganese (sliding) theory, capacity is about 200 mah/g.

According to the bucket theory, the water level is determined by the shortest part of the bucket, and the energy density of a lithium-ion battery depends on the anode material.

The platform for the 3.2 V voltage of the lithium iron phosphate, the ternary index is 3.7 V. Comparison of the two, high energy density, a difference of 16%.

Summarize

Of course, in addition to the chemical system, production technology level, such as compaction density, and thickness of the foil, will also affect the energy density of lithium-ion batteries. Generally speaking, the greater the compaction density, the higher the capacity of the battery in a limited space, therefore, the main material of compaction density was seen as one of the reference indexes of the battery energy density.

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