Have you ever wondered about the different types of batteries that power the devices around us—from cleaning robots and smartphones, to e-bikes, electric vehicles (EVs), and even large industrial machines?

When choosing a product that uses rechargeable batteries, what should we know? And how do we determine which battery is right for a specific job?

Since SONY commercialized the 18650 cell in the 1990s, lithium-ion batteries have evolved rapidly. Many new chemistries and form factors have emerged to support diverse applications. Understanding these fundamentals not only helps us appreciate the batteries that power our electrified world, but also guides us in selecting the most suitable solutions for each scenario.

1. First Things First: Battery Chemistry Basics

1.1 NCM & NCA Battery Cells

NCM stands for Nickel–Cobalt–Manganese. It is one of the most widely used lithium-ion chemistries.
Typical variants include:

• NMC811 → 80% nickel, 10% manganese, 10% cobalt
• NMC622 → 60% nickel, 20% manganese, 20% cobalt
• NMC523 → 50% nickel, 30% manganese, 20% cobalt

NCA (Nickel–Cobalt–Aluminum) is similar to NCM but uses aluminum instead of manganese. Its common ratio is:

• NCA → 80% nickel, 15% cobalt, 5% aluminum

These formulations are fine-tuned depending on performance targets—energy density, safety, lifespan, and cost.

Advantages of NCM Batteries

High energy density
NCM cells store significantly more energy per unit volume than LFP, making them ideal for EVs, power tools, and devices requiring long runtime.

Good low-temperature performance
They maintain better performance in cold climates, especially compared to LFP.

High discharge & fast-charging capability
They support high power output and faster charging speeds, suitable for high-performance applications.

Flexible material tuning
Manufacturers can adjust nickel, manganese, and cobalt ratios to optimize for energy density, safety, or lifespan.

Disadvantages of NCM Batteries

Higher cost
Nickel and cobalt are expensive and subject to supply chain volatility.

Shorter cycle life
Typically 1,000–2,000 cycles—much lower than LFP’s 2,000–5,000+ cycles.

Lower thermal stability
NCM is more prone to overheating and requires tighter thermal management.

Environmental and ethical concerns
Cobalt sourcing raises sustainability and mining-related human rights issues.

1.2 Lithium Iron Phosphate (LFP)

LFP stands for Lithium Iron Phosphate. Unlike NCM/NCA, it does not require nickel or cobalt, making it more cost-effective and environmentally friendly.

Advantages of LFP

• Long lifespan – Often exceeds 2,000+ cycles
• Lower cost – Abundant and inexpensive raw materials
• High safety – Strong resistance to overheating and thermal runaway
• More eco-friendly – No cobalt or nickel extraction impact

Disadvantages of LFP

• Lower energy density – Less energy stored per unit volume
• Slower charging – Generally longer charging time
• Poor low-temperature performance – Noticeable performance drop in cold climates

2. Battery Form Factors

2.1 Prismatic Cells

Typically rectangular in shape. They are widely used in EVs and energy storage systems due to efficient space utilization.

2.2 Cylindrical Cells

Highly standardized and manufactured at scale.
They offer:

• Strong mechanical stability
• Excellent heat dissipation
• High discharge capability

This makes cylindrical LFP cells ideal for e-bikes, scooters, power tools, and other compact high-drain applications.

2.3 Pouch Cells

Lightweight and flexible, commonly used in smartphones, tablets, drones, and some EV platforms.

3. Major Cylindrical Cell Sizes and Use Cases

Below is an overview of common cylindrical cells, their dimensions, chemistry, and typical applications.

3.1 18650: The Classic Standard

First introduced by Sony in 1991, the 18650 remains the most widely used cylindrical cell today.
It provides an excellent balance of size, performance, and cost.

Applications include:

• Consumer electronics
• Medical equipment
• E-bikes and scooters
• Industrial tools
• Even early Tesla EVs

Available in both NCM and LFP versions.

3.2 21700: More Power in a Similar Footprint

The 21700 cell increases both diameter and height compared to the 18650, enabling capacities around 4500–5000 mAh.

Tesla popularized this format, and many EV and tool manufacturers have since adopted it.
It remains the mainstream choice for high-performance EV models while 4680 production continues scaling.

3.3 26650: High-Power Performance

The 26650 (26mm × 65mm) offers higher capacity than the 18650 and supports high discharge rates.

Applications include:

• Power tools
• E-bikes
• Medical equipment
• Commercial devices requiring pulse power

Its larger size enhances performance but requires proper thermal management.

3.4 26700: LFP-Specific Evolution

The 26700 is an LFP-focused format, close to the 26650 in size but optimized for applications needing:

• High safety
• High cycle life
• Stable discharge performance

Common in mobility devices, industrial tools, and consumer equipment.

3.5 32140: Large-Format LFP Cell

A sizable LFP cell (32mm × 140mm), the 32140 is designed for:

• e-mobility
• industrial machinery
• high-drain commercial devices

Its large capacity provides long runtime and stable power delivery.

3.6 4680 / 4695 / 46120: The New Generation

First introduced by Tesla, the 4680 cell promises higher pack energy density and lower cost due to its large size and simplified pack design.

However, Tesla’s innovative dry-electrode process still faces mass-production challenges.

Meanwhile, Chinese manufacturers (CATL, EVE, BYD, Gotion) are promoting 4695 and 46120 variants using mature wet-process cathodes.
These cells began entering selected EV models in late 2024 and are expected to see broader adoption across premium EVs by 2026.

Part 2: Key Factors for Choosing the Right Battery Size

Selecting the right cylindrical battery involves more than just picking a form factor.

2.1 Application-Specific Requirements

Different applications require different characteristics:

• NCM:
  160–270 Wh/kg, ~1,000–2,000 cycles → Best for compact designs needing high energy density
• LFP:
  100–180 Wh/kg, 2,000–5,000 cycles → Best for durability and long service life

Choosing the correct chemistry ensures the battery pack meets expectations for capacity, energy output, and longevity.

2.2 Compatibility With Devices and Systems

Batteries must match:

• Voltage requirements
• Capacity expectations
• Physical size constraints
• BMS (battery management system) integration

Choosing the wrong chemistry or size can lead to:

• Poor performance
• Safety risks
• Increased maintenance
• Unnecessary cost

2.3 Balancing Energy Density, Size, and Cost

Every chemistry has trade-offs:

• High energy density (NCM/NCA) → Smaller size, higher cost, shorter cycle life
• Long lifespan (LFP) → Larger volume, lower cost

Understanding these trade-offs helps optimize battery pack design for your application.

2.4 Availability and Supply Chain Considerations

Material availability (especially cobalt and nickel) affects supply stability.
As the world moves toward a projected 1,200 GW of energy storage by 2030, robust supply chains and reliable manufacturing partners become critical.

Partnering with trusted suppliers ensures:

• Consistent quality
• Stable delivery
• Long-term reliability

Final Thoughts

Cylindrical lithium-ion batteries come in many sizes and chemistries, each tailored for specific performance requirements. Whether you’re building an e-bike pack, designing an industrial tool, or evaluating EV cells, understanding the fundamentals—form factor, chemistry, performance, and supply chain—ensures you choose the right battery for your application.