What’s the Difference Between Lithium-Ion (Li-Ion) and Lithium Polymer (LiPo) Batteries?

Choosing the right battery chemistry for an application depends on the chemistry features, pros, cons, and drawbacks, as well as the requirements for its use. Lithium-ion and lithium polymer batteries offer different capabilities across a range of factors, and it is important to consider the form flexibility, charging, and cost to find a solution that delivers the optimal performance. By exploring the differences between lithium-ion and lithium polymer batteries, we can help you determine which option might be best for your application.

What is a Lithium-Ion Battery?

Lithium-ion batteries have lithium ions that move between two electrodes to produce and store energy. During charging, ions move from the positive electrode to the negative electrode, and during discharging, they move in the opposite direction. With a combination of lightweight design and high-density, stable power output, lithium-ion batteries are among the most widely used battery technologies today, often found in laptops, power tools, medical devices, industrial equipment, robotics, and portable electronics.

What is a Lithium Polymer Battery?

Lithium polymer (LiPo) batteries are lightweight, rechargeable power solutions known for delivering high energy quickly. Compared to lithium-ion batteries, they use a gel-like or solid polymer electrolyte instead of a liquid one, and they typically have shorter lifespans. These batteries often feature a flexible, soft-pack design which allows them to be manufactured in custom, compact shapes, making them ideal for a wide range of space-constrained devices.

Li-Ion vs. LiPo Battery Chemistries

Lithium-Ion Batteries Lithium Polymer Batteries
Energy Density 90-350 WH/Kg 140-200 WH/Kg
Weight Heavier due to metal enclosure Typically light due to foil package instead of metal can
Form Flexibility Limited shapes in cylindrical and prismatic sizes Flexible, easy to customize
Charging Performance Supports fast charging, typically up to 1C charging, higher rates for some cell types Supports fast charging, typically up to 1C charging; more for specialty cells
Lifespan 500-1000 cycles, depending on usage pattern and application 500-1000 cycles, depending on usage pattern and application
Cost Usually lower due to scales of manufacturing and highly automated assembly Usually higher due to scales of manufacturing and lack of automation

When properly designed, both Li-ion and LiPo batteries are safe, but the risks associated with each slightly differ. Due to their gel-like electrolyte, lithium polymer batteries have a lower risk of leakage and combustion and better resistance to mechanical stress, reducing the risk of internal damage. Lithium-ion batteries require battery management systems (BMS) and built-in protection to monitor their performance, featuring safeguards that reduce the risks of overheating, overcharging, and thermal runaway. It is essential to consider the pros and cons of each chemistry to ensure the right solution is chosen for the application.

Pros and Cons of Li-Ion and LiPo Battery Chemistries

Depending on the needs of your application, lithium polymer and lithium-ion batteries offer a range of pros and cons to suit your requirements. Lithium polymer batteries offer greater shape flexibility, high discharge rates, and low self-discharge; however, they have a shorter lifespan than lithium-ion batteries, require strict maintenance to ensure balanced cells, and are more expensive. Alternatively, lithium-ion batteries offer high energy density and efficiency, with cost savings from reduced operational and energy expenses. Their drawbacks stem from potential design issues and poor BMS integration, which could lead to thermal runaway.

Best Use Cases: Which Battery is Better for Applications?

While in some instances lithium-ion and lithium polymer batteries may be interchangeable, they are often preferred for specific applications based on their specific features and capabilities, such as:

  • Smartphones, tablets, and wearables: Lithium polymer batteries are typically preferred for these applications as they allow for exceptionally thin, lightweight, and customizable designs due to their flexible polymer electrolytes.
  • Laptops and portable electronics: These applications can use either lithium-ion or lithium polymer batteries to achieve optimal performance, depending on their specific requirements.
  • Drones, RC equipment, and high-performance portables: Providing massive amounts of instant power, lithium polymer batteries are the standard for these applications due to their higher discharge rates.
  • Industrial equipment, medical devices, robotics, and portable power systems: Lithium-ion batteries offer high energy density, lightweight construction, and long cycle life that deliver advantages in runtime and durability for these applications.

Contact Us for Custom Battery Solutions Compatible with Your Application

Apex Mobile Power (AMP) offers over 100 years of combined engineering experience to deliver high-quality custom battery solutions. Specializing in lithium-ion batteries and other battery chemistries, we have the capabilities to design and manufacture batteries that meet your exact design and performance requirements across various industries. To discuss your project, contact AMP today or request a quote to begin.

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