21700 Batteries | Durable Lithium-Ion Power Solutions

A 21700 battery is a high-capacity, rechargeable lithium-ion cell with a cylindrical shape and standard dimensions of 21mm in diameter and 70mm in length. Originally developed to improve upon the popular 18650 battery, 21700 cells offer higher energy density, increased capacity, and improved efficiency—making them a preferred choice for high-power applications like electric vehicles, high-drain flashlights, power tools, and energy storage systems.

Key Features & Technical Specifications

• Chemistry: 21700 batteries are available in different lithium-ion chemistries, each offering unique advantages:

  • Lithium Cobalt Oxide (LiCoO₂ - LCO): High energy density but lower discharge rates.
  • Lithium Manganese Oxide (LiMn₂O₄ - LMO): Enhanced thermal stability and safety.
  • Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO₂ - NMC): A balance of power, energy density, and safety.
  • Lithium Iron Phosphate (LiFePO₄ - LFP): Superior cycle life and safety with lower energy density.

• Voltage: Typically 3.6V or 3.7V nominal, with a full charge voltage of 4.2V and a discharge cutoff around 2.5V - 3.0V.

• Capacity: Ranges from 3000mAh to 5000mAh+, depending on chemistry and brand.

• Discharge Rate (CDR): Some high-drain 21700 cells support continuous discharge rates of 30A, 40A, or more, making them ideal for demanding applications.

• Cycle Life: Depending on usage and chemistry, these batteries can last 500 to over 1500 charge cycles.

Protected vs. Unprotected 21700 Batteries

• Protected 21700 Batteries: Feature an internal protection circuit to prevent overcharging, over-discharging, and short circuits. Due to the built-in safety mechanism, these batteries are slightly longer than 70mm.
• Unprotected 21700 Batteries: Do not include a built-in safety circuit and are typically used in battery packs with an external Battery Management System (BMS).

Common Applications of 21700 Batteries

21700 batteries are widely used across multiple industries due to their high energy density and powerful performance. Some of the most common applications include:
✅ Electric Vehicles (EVs): Used by Tesla and other automakers for long-range, efficient power storage.
✅ Flashlights & Consumer Electronics: High-powered LED flashlights, power banks, and vaping devices.
✅ Power Tools & Industrial Equipment: Essential for cordless drills, saws, and heavy-duty machinery.
✅ Renewable Energy Storage: Solar power systems, backup UPS power supplies, and off-grid energy storage solutions.

Choosing the Right 21700 Battery

Before purchasing a 21700 battery, consider the device manufacturer’s specifications to ensure compatibility and safety. Some key factors include:
🔹 Flat Top vs. Button Top: Button top batteries have a protruding positive terminal, while flat tops sit flush.
🔹 High-Drain vs. Standard Cells: Devices requiring fast power delivery (e.g., power tools, flashlights) benefit from high-discharge rate cells.
🔹 Protected vs. Unprotected: If using in standalone applications, consider protected cells for added safety.

At 18650Battery.com, we offer a curated selection of authentic, high-quality 21700 batteries from trusted brands, ensuring top performance, reliability, and safety. Explore our collection today to find the right power solution for your needs.