21700 Cylindrical Lithium-Ion Battery Cell

Drone Battery

ENOV High-Energy drone batteries power industrial and commercial drones. Delivering 220–320 Wh/kg energy density, they enable long flight times (30+ mins) and support fast charging (2C). Perfect for aerial photography, surveillance, and delivery drones.

The 21700 cylindrical lithium-ion battery cell is a key specification in the lithium-ion battery field. With its balanced performance in capacity, energy density, and power output, it has become a core power supply component for high-energy-consumption equipment and large-scale energy storage scenarios. Its technological iteration and application expansion are driving the upgrading of related industries.

I. Core Specifications and Parameters

● Size Identification: In the model, “21” represents a diameter of 21 millimeters, “70” denotes a height of 70 millimeters, and “0” indicates a cylindrical structure. The length of some protected products slightly exceeds 70 millimeters.

● Weight Range: The weight of a single cell is approximately 60-70 grams, with specific values varying slightly by manufacturer and chemical composition.

Voltage Parameters: The nominal voltage is typically 3.6V-3.7V, the charging cut-off voltage is 4.2V, and the discharge termination voltage is 2.5V-3.0V, complying with general industry standards for lithium-ion batteries.

● Capacity Performance: The conventional capacity range is 3000mAh-5000mAh, high-end high-performance products can reach 6500mAh, and mainstream products are concentrated in the 4000mAh-5000mAh range.

● Discharge Capacity: The continuous discharge current spans a wide range. Ordinary models range from 5A to 10A, power-type models can reach 15A-35A or more, and some high-rate models support higher current output.

● Cycle Life: Depending on the chemical composition and manufacturing process, the cycle life ranges from 500 to 3000 cycles, and lithium iron phosphate (LFP) system products can achieve 5000 cycles.

● Energy Density: The conventional range is 250Wh/kg-300Wh/kg. High-end models using high-nickel ternary materials and silicon-carbon anodes can break through 320Wh/kg in energy density.

II. Core Performance Advantages

● Capacity and Space Efficiency: Compared with the traditional 18650 battery cell, the volume increases by approximately 35% while the capacity can be improved by up to 50%. When composing a battery pack with the same total capacity, fewer cells are required, simplifying the battery management system and improving space utilization.

● Enhanced Energy Density: Achieved not only through volume expansion but also by optimizing chemical ratios, such as reducing cobalt content, increasing nickel content, or adopting a combination of third-generation high-nickel ternary materials and silicon-carbon anodes.

● Excellent Discharge Performance: Supports high-rate discharge, capable of releasing large currents instantaneously. It perfectly adapts to equipment requiring sudden power output, meeting the needs of rapid acceleration or high-intensity operation.

● Thermal Management and Safety: The larger size design improves heat dissipation efficiency, reducing temperature rise during high-load operation. Some products are equipped with explosion-proof valves, Current Interrupt Devices (CID), and Positive Temperature Coefficient (PTC) thermistors to further enhance safety performance.

● Structural Stability: The cylindrical design provides good mechanical stability, resisting deformation under complex environments such as vibration and impact, and is suitable for harsh usage scenarios.

III. Main Application Scenarios

● Electric Vehicles: Pioneered by models such as the Tesla Model 3, it effectively improves vehicle range and power performance, with many mainstream automakers following suit.

● Power Tools: Suitable for equipment such as electric drills, angle grinders, and electric saws. Its high discharge rate and durability meet the requirements of high-intensity and frequent use.

● Energy Storage Systems: Used in renewable energy storage equipment such as solar and wind energy systems, as well as UPS backup power systems, stably storing excess electrical energy and balancing grid loads.

● Consumer Electronics: Applicable to high-power power banks, high-performance laptops, game consoles, high-lumen flashlights, and other products with high requirements for battery life and power, supporting high-power fast-charging solutions such as 140W.

● Other Fields: Including household vacuum cleaners, drones, robots, medical equipment, emergency lighting systems, covering multiple scenarios in industry, people’s livelihood, and professional equipment.

IV. Core Comparison Between 21700 and 18650 Battery Cells

Comparison Item	21700	18650
Size	Diameter 21mm, Height 70mm	Diameter 18mm, Height 65mm
Volume Comparison	Overall volume is more than 20% larger than that of 18650	–
Capacity Range	3000mAh-6500mAh, mainstream 4000mAh-5000mAh	1000mAh-3600mAh, mainstream 2200mAh-3400mAh
Energy Density	Generally above 250Wh/kg, up to 320Wh/kg for high-end models	Up to approximately 270Wh/kg
Application Focus	Suitable for electric vehicles, large-scale energy storage systems, high-power equipment, etc.	Small and medium-sized consumer electronics, lightweight power tools, etc.
Grouping Efficiency	Fewer cells required for grouping, higher space utilization	High standardization, adapting to the battery compartment design of a large number of existing devices
Cycle Life	High-nickel systems and full-tab technology enable better lifespan performance under high-rate usage scenarios	Similar cycle life ranges for both

V. Usage and Selection Recommendations

● Match Application Requirements: For high-power equipment, prioritize high-discharge-rate models; for long-term use equipment, select high-capacity products above 4000mAh; for energy storage scenarios, lithium iron phosphate (LFP) systems can be preferred for longer cycle life.

● Pay Attention to Compatibility: Confirm whether the device’s battery compartment size is compatible with the 21700 specification. Distinguish between button-top and flat-top, protected and unprotected products to avoid installation conflicts.

● Standardize Usage and Maintenance: Avoid overcharging and deep discharging, use compatible chargers, and store in a cool and dry environment to significantly extend the battery cell’s service life.