What is the Difference Between EV Battery and Mobile Phone Batteries?

Although both mobile phone batteries and car power batteries are called “lithium batteries“, they are very different in design, performance, and application scenarios, just like the difference between bicycles and trucks. The main differences are reflected in the following aspects:

1. Core Purpose and Working Environment:

1. Mobile Phone Batteries: Provide energy for portable electronic devices, and the working environment is relatively mild (room temperature, low vibration, no impact). The main concerns are high energy density (storing more power in a limited volume/weight), safety (in small devices), low cost and thin appearance.
2. EV Batteries: Provide powerful power for driving vehicles, and the working environment is extremely harsh (high and low temperature, severe vibration, impact, possible collision). The core requirements are high power density (fast charging and discharging to provide power), ultra-long cycle life (withstand thousands of charging and discharging times), extremely high safety standards (prevent thermal runaway from causing fire), wide temperature operating range and cost control under large-scale production.

2. Battery Type

1. Mobile phone batteries: Almost all use lithium-ion polymer batteries. This type of battery uses an aluminum-plastic film soft package, has a flexible shape (bendable, special-shaped), high energy density, is relatively safe, and is suitable for small devices.

2. EV batteries: Mainly lithium-ion batteries, but the battery cell forms are different:
   ■Prismatic Cell battery: Very mainstream, with a solid shell (aluminum/steel), easy to stack into groups, high structural strength, and relatively easy heat dissipation design.
   ■Cylindrical Cell battery: Such as the 21700 or 4680 batteries used by Tesla, with a high degree of standardization, high production efficiency, and cost advantages, but the grouping requires more support structures.
   ■ Pouch Cell battery: There are also applications, and the energy density may be higher, but the grouping process and mechanical protection requirements are extremely high.
3. Battery Cathode materials:
   • Ternary lithium or lithium iron phosphate is more commonly used in automotive batteries. Ternary lithium has high energy density and good low-temperature performance; lithium iron phosphate has low cost, long cycle life and good safety.
   • The cathode materials of mobile phone batteries tend to have higher energy density, such as lithium cobalt oxide (LCO) or its improved versions.

3. Voltage and Capacity

1. Mobile phone battery: The voltage of a single cell is usually 3.7V or 3.8V (nominal), and the capacity is generally between 2000mAh and 5000mAh (i.e. 7.4Wh to 19Wh).
2. EV battery: A huge battery pack composed of hundreds of single cells connected in series and parallel. The total voltage is usually between 300V and 800V or even higher (such as 800V high-voltage platform). The total capacity is huge, usually between 40kWh and 100+kWh (i.e. 40,000Wh to 100,000+Wh).

The energy stored in an ordinary 50kWh electric vehicle battery pack is equivalent to about 2500 to 5000 ordinary mobile phone batteries!

4. Charge and discharge rate:

1. Mobile phone battery: Support fast charging (such as 30W, 65W, 120W), but the power is relatively small (tens of watts). The discharge power is also small, which can meet the needs of processors, screens, etc.
2. EV battery: Need to support extremely high charge and discharge power. The drive motor may need to output hundreds of kilowatts of power instantly (acceleration). Super fast charging (such as 250kW, 350kW) requires huge energy input in a short time. This is a huge challenge to the battery’s rate performance and thermal management.

5. Cycle life:

1. Mobile phone batteries: The design life is usually 500 full charge and discharge cycles to maintain more than 80% capacity. Due to daily charging, the actual service life is generally 2-3 years.
2. EV batteries: Require ultra-long life, the goal is to maintain more than 80% capacity after 1,000, 2,000 or even more full charge and discharge cycles (usually 8 years or 160,000 kilometers of warranty). This places extremely high demands on battery cell materials, manufacturing processes and battery management systems.

6. Thermal management system:

1. Mobile phone battery: Heat dissipation mainly relies on passive heat dissipation of the mobile phone shell, and the structure is simple. Performance will decrease in low temperature environment.
2. EV battery: Extremely complex and critical. Active thermal management system must be equipped:
   ■ Liquid cooling system: The most common, the temperature is precisely controlled by the coolant flowing through the pipes or cold plates inside the battery pack.
   ■ Air cooling system: Low cost, limited heat dissipation capacity, mostly seen in early or low-end models.
   ■ Heating system: Heat the battery in a low temperature environment to ensure performance and charging speed (such as PTC heater, liquid heat). ■ The battery management system monitors the temperature of each battery cell or module in real time and precisely controls the cooling/heating system.

7. Battery Management System:

1. Mobile phone battery: BMS is very simple and integrated on the motherboard. Its main function is to prevent overcharging, over-discharging, short circuit and calculate the remaining power.
2. EV battery: Extremely complex and crucial. Responsible for:
   ■ Monitoring the voltage, temperature and current of hundreds of cells.
   ■ Battery status estimation: Accurately calculate the state of charge, health status and power status.
   ■ Battery balancing: Ensure the voltage between series cells is consistent to prevent overcharging/over-discharging of individual cells.
   ■ Thermal management control.
   ■ Fault diagnosis and protection: Multiple safety redundancy designs to prevent thermal runaway.
   ■ Communicate with the vehicle controller.

8. Safety requirements:

1. Mobile phone batteries: Safety is important, but the energy of a single cell is small, and the scope of failure is limited (such as expansion and fire usually damage the mobile phone itself).
2. EV batteries: Safety is the top priority! Single cells have large energy, and the energy after grouping is huge. Once thermal runaway occurs (a battery cell catches fire and triggers a chain reaction), the consequences may be catastrophic (the whole vehicle catches fire or even explodes).
   Therefore, there are extremely strict safety standards and tests (such as needle puncture, extrusion, fire, overcharge and over discharge, seawater immersion, etc.), and multiple protection measures are taken in battery cell design, grouping process, thermal management, BMS, physical protection structure, etc.

9. Cost:

1. Mobile phone batteries: The cost is relatively low, usually from 10 to hundreds of RMB.
2. EV batteries: The cost is very high, and is one of the most expensive parts of electric vehicles, usually accounting for 30%-50% of the total vehicle cost. The price of a battery pack ranges from tens of thousands to hundreds of thousands of RMB. Although the unit energy cost is continuing to decline.

10.Shape and size:

• Mobile phone battery: The shape is highly customized to fit the internal space of the mobile phone (special shape, thin sheet).
• EV battery: The battery pack is usually a huge rectangular structure installed on the vehicle chassis (“skateboard chassis”) to lower the center of gravity and utilize space. The interior is composed of standardized modules (composed of multiple single cells) or directly cell-to-pack technology.

Comparison summary between mobile phone batteries and EV batteries: