The improved performance and life cycle benefits when developing graphene-based batteries over conventional metal-ion batteries are well worth the resource investment.
Traditional Battery Technology
Lithium is the common material used in both rechargeable and non-rechargeable batteries. Although alkaline- and zinc-based batteries are available, they typically have a shorter service life because of their high charge density. Unlike lithium-based batteries, these batteries cannot operate at higher voltages.
A primary (non-rechargeable) battery is composed of two electrodes, allowing current flow in one direction only, via an intermediary electrolyte. Secondary (rechargeable) batteries still contain two electrodes, but lithium ions can flow in both directions depending on if charging or discharging.
The anode is typically a lithium-based (metal oxide) compound and the cathode is a porous carbon. Both the anode and cathode have a rigid structure with defined holes, enabling the absorption of lithium ions into the holes upon the application of current. The ions desorb into the electrolyte solution when there is no current being applied.
Absorption of the lithium ions can take place on both the cathode and the anode. The ions move towards to the cathode when a battery is being used. During charging, the current is reversed and the ions are absorbed into the anode. This process allows for many cycles to be produced, resulting in an enhanced lifespan. The material of choice for cathodes is traditionally graphite, but it can vary for anodes. The most common types include Li4Ti5O12, LiNiCoAlO2, LiFePO4, LiNiMnCoO2 (NMC), LiCoO2, and LiMn2O4.
Graphene Battery Technology
The structure of graphene battery technology is similar to that of traditional batteries, where two electrodes and an electrolyte solution are used to facilitate ion transfer. The main difference between graphene-based batteries and solid-state batteries is in the composition of one or both electrodes.
The change primarily lies in the cathode, but it is also possible to utilize carbon allotropes in the anode. The cathode in a conventional battery is purely composed of solid-state materials, but a composite-a hybrid material containing a solid-state metallic material and graphene is used as the cathode in a graphene battery.
Depending on the intended application, the amount of graphene in the composite can differ. The amount of graphene incorporated into the electrode is usually based on the performance requirements and depends upon the existing efficiencies and/or weaknesses of the solid-state precursor material.