Differences Between Supercapacitors and Batteries

Supercapacitor vs Battery: It is like comparing a sprinter to a marathon runner. Both perform the same task of energy storage but have different advantages and disadvantages ideally suited to their respective uses. So how do supercapacitors compare with the most common type of battery, the lithium-ion (Li-ion) battery?

What is a Supercapacitor?

Supercapacitors store energy through two mechanisms: electrostatic and electrochemical. In electrostatic storage, charge is separated at the electrode-electrolyte interface, forming an electric double layer of ions. This double-layer capacitance stores energy without chemical reactions occurring within the cell. The stored energy can be released quickly when needed. The electrochemical mechanism involves redox reactions, where charge is stored through ion movement between the electrolyte and electrodes. Supercapacitors can harness either or both mechanisms depending on their application.

What is a Lithium-Ion Battery?

Lithium-ion batteries are the most common type of rechargeable electric battery. They store electricity through an electrochemical process, meaning they convert electricity into chemical energy and back again as needed. Lithium-ion batteries are well suited for portable high-energy density storage systems because of their high volumetric and gravimetric energy density. They are used in a range of devices, from electric vehicles to smartphones and laptops.

Comparison of Supercapacitor and Lithium-Ion Battery Advantages and Disadvantages:

Energy Density: Supercapacitors store much less energy per unit volume or weight than traditional batteries. In EVs, energy density translates into the driving range per charge. Hence, batteries are more suitable for applications that require large energy storage.

Power Density: Supercapacitors can deliver large amounts of energy in short periods, making them ideal for applications that require rapid power use. Fast acceleration in electric vehicles and camera flashes are such applications.

Self-Discharge: Batteries have much lower self-discharge rates compared to supercapacitors. Thus, batteries are better suited for applications needing long-term energy storage without frequent recharging.

Lifespan: In batteries, components corrode due to chemical reactions. Thus, while supercapacitors can handle over 1,000,000 charge/discharge cycles, ordinary batteries can withstand only about 2,000 to 3,000 cycles.

Cost: Supercapacitors typically have a higher cost per watt due to component costs and the fact that they discharge power very quickly, which can be inefficient.

Sustainability: The mining of lithium, nickel, and cobalt for lithium-ion batteries involves environmental issues related to waste and pollution. In contrast, supercapacitors can use more sustainable materials like activated carbon from biomass precursors that are more renewable and easier to recycle, and less harmful to the environment.

Which Technology is Better?

Ultimately, choosing between supercapacitors and batteries depends on the application. Both offer considerable value and sometimes work best when both are used! For example, a bus equipped with both can use a capacitor for acceleration when needed and rely on the battery for maintaining a constant speed.

However, much exploration is still required for both batteries and supercapacitors. There is ongoing research to find and perfect new materials and chemistries that can enhance the energy density, discharge capacity, cycling durability, and safety of batteries and supercapacitors.

Analytical Solutions for Supercapacitor and Battery Research

Malvern Panalytical provides reliable, accurate, and diverse tools that enable researchers and manufacturers to develop high-performance batteries and supercapacitors while reducing environmental impact.

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

The Mastersizer and Zetasizer Advance ranges enable particle characterization in terms of size and size distribution.

The Empyrean and compact Aeris X-ray diffraction equipment can analyze supercapacitor and battery materials for crystallographic defects that negatively impact battery performance.