What is the difference between supercapacitors and batteries?

Supercapacitor vs battery: it’s like comparing a sprinter to a marathon runner. They both do the same thing – namely, store energy – but have different strengths and weaknesses that make each one ideally suited for its intended application. How then do supercapacitors compare to the most common type of battery, the lithium-ion (Li-ion) battery?

What are supercapacitors?

Supercapacitors store energy through two mechanisms: electrostatic and electrochemical. In the electrostatic storage, charges are separated at the electrode-electrolyte interface, resulting in the formation of an electric double layer of ions. This double-layer capacitance stores energy without any chemical reactions inside the cell. The energy stored in this manner can be released quickly when needed. The electrochemical mechanism involves redox reactions, where charge is stored via movement of ions between the electrolyte and the electrode. Supercapacitors can utilize one or both mechanisms, depending on their intended application.

What are lithium-ion batteries?

Li-ion batteries are the most common type of rechargeable electric battery. Batteries store electricity through electro-chemical processes—converting electricity into chemical energy and back to electricity when needed. Li-ion batteries have the highest volumetric and gravimetric energy density making them suitable for portable high energy density storage systems. Li-ion batteries are used in numerous devices, from electric vehicles to smartphones and laptops.

Supercapacitors vs Li-ion batteries: Pros and cons

• Energy Density: Supercapacitors store much less energy per unit volume or weight compared to conventional batteries. In EVs, energy density translates to mileage per charge. Thus, batteries are more suitable in applications requiring large energy storage.
• Power Density: Supercapacitors can deliver large energy in a short time, making them ideal for applications requiring rapid power usage. Fast acceleration of electric vehicles and camera flashes are such applications.
• Self-Discharge: Batteries have much lower self-discharge rate compared to supercapacitors. Thus, batteries are more suitable for applications requiring long-term energy storage without frequent recharging.
• Lifetime: In batteries, the chemical reaction corrodes the components – so while supercapacitors can handle more than 1,000,000 charge/discharge cycles, a normal battery can only withstand about 2,000 to 3,000 cycles.
• Cost: Supercapacitors typically have a higher cost per watt, due to the cost of the components and the fact that the power is discharged very quickly and therefore sometimes inefficiently.
• Sustainability: Mining the lithium, nickel, and cobalt required for a Li-ion battery comes with environmental concerns around waste and pollution. In contrast, supercapacitors can use more sustainable materials, such as activated carbon from biomass sources that are more renewable, less harmful to the environment, and easier to recycle.

Which technology is best?

In short, the choice of supercapacitor or battery all depends on the application. Both provide substantial value – and sometimes they work best as a team! For example, a bus equipped with both can use its capacitors to accelerate when needed, with the batteries taking over when a steady speed is to be maintained.

However, a lot remains to be explored in both batteries and supercapacitors. That is why there is so much research to find and perfect new materials and chemistries that can enhance the energy density, discharge capacity, cycling durability, and safety of both batteries and supercapacitors.

Analytical solutions for supercapacitors and batteries research

At Malvern Panalytical, we offer a wide range of reliable, accurate, and versatile tools to help researchers and manufacturers develop high-performance batteries and supercapacitors with a reduced environmental footprint.

For example, our Zetium or Epsilon range of X-ray fluorescence spectrometer can be used to analyze elemental composition and impurities in cathode, anode and electrolyte materials.

Mastersizer and Zetasizer Advance ranges enable particle characterization for size and size distribution.

Empyrean and compact Aeris X-ray diffraction instruments, can analyze supercapacitor and battery materials for crystalline defects that adversely affect the battery performance.

Visit this page for more details on how our solutions can help you accelerate your research on energy storage materials.