During the or the Electric motors in an electrified car are quite simplethe cell chemistry of the battery pack determines the range, charging speed, service life and also the character or market position of the vehicle itself. Most vehicles from leading electric car manufacturers such as Tesla, Audi, BMW, Hyundai, Kia, VW or BYD use different lithium-ion variants, each of which reflects specific material and system decisions.

Lithium-ion battery

The majority of electric cars use lithium-ion cells. Their basic principle is identical: lithium ions intercalate into the graphite anode when charging and migrate back to the cathode when discharging. The differences lie primarily in the cathode chemistry. NMC (Nickel-Manganese-Cobalt) NMC cells are currently particularly widespread in Europe. Typical versions are NMC 622 or 811 – the numbers indicate the ratio of the metals. Many European models from Volkswagen or BMW continue to use NMC in mid-range and luxury vehicles because the high volumetric energy density enables compact range packages. Characteristics:

• Energy density: 200-270 watt-hour per kilogram (cell level)
• Cell voltage: approximately 3.6-3.7 volts
• Good balance between energy density and performance
• Sensitive to thermal runaway if mishandled
• Complex thermal management (liquid cooling plates, integrated cooling channels)
• Precise BMS monitoring (State of Charge, State of Health)
• Cost and supply chain dependency on rare earths such as cobalt

• Energy density of up to around 300 watt-hour per kilogram
• Very high specific energy
• Increased requirements for security systems

LFP (lithium iron phosphate)

LFP batteries are experiencing a bit of a renaissance, especially in high-volume models. The big advantage lies in the intrinsic safety: the phosphate structure significantly reduces the risk of exothermic chain reactions. In addition, LFP cells tolerate frequent full charges better, which is relevant in everyday life. Manufacturers like BYD (with the self-developed “Blade Battery”) or basic versions from Tesla rely heavily on LFP – especially for standard range models. The lower energy density is often compensated for by structural integration (cell-to-pack or cell-to-body), thereby reducing packing overhead.

• Energy density: 150-200 watt-hour per kilogram
• Cell voltage: approximately 3.2 volts
• Very high thermal stability
• Lower material costs (no nickel, no cobalt)

Cell formats: Round, prismatic or pouch

Na ion (sodium ions)

A new trend is batteries in which the comparatively cheap common salt (sodium) challenges the expensive lithium. Battery manufacturers such as CATL are currently ramping up production. Advantage: Sodium is available everywhere. These batteries still work very well even at -30 °C, where lithium batteries often fail. On the other hand, the energy density is lower at around 150 Wh/kg. Therefore, these batteries are more likely to be installed in inexpensive, smaller electric cars.

• Energy density: around 150 watt-hour per kilogram
• Cell voltage: approximately 3.2 volts
• high thermal stability
• significantly cheaper (no lithium)

Structural integration: From module to load-bearing component

In addition to the chemistry, the mechanical design is crucial. Round cells known in 18,650, 2170 or 4680 formats (e.g. at Tesla). Advantages: – Very good heat dissipation – Mechanical stability – High degree of automation Disadvantage: – Lower packing density due to gaps Prismatic cells Cuboid-shaped, often in European platforms (e.g. modular electrical kit from Volkswagen).

• Good volumetric utilization
• Fewer electrical connection points
• Pouch cells
• Flexible foil cover, high energy density, but mechanically more sensitive.
• Require complex compression in the module.

Thermal management and charging capability

Current developments are moving the battery from pure energy storage to a structural vehicle component:

• Cell-to-Pack (CTP): Elimination of classic modules
• Cell-to-Body (CTB): Integration into the body structure

These approaches increase system energy density by up to 10-20%, reduce mass, and improve stiffness. Manufacturers like BYD and Tesla are pushing this integration hard.

Solid state batteries

The charging power of modern vehicles (up to over 500 kW DC) places extreme demands on:

• Internal resistance of the cells
• Lithium plating avoidance
• Coolant routing
• Temperature homogeneity

Solid-state cells are about to enter series production. They replace the liquid electrolyte with a solid ion carrier.

• Significantly higher energy density (>400 possible)
• Minimized fire risk
• Potentially faster charging capability

The original for this post “Full charge” comes from AutoTest&Technik.