Hydronium-ion battery is world’s first

Materials World magazine
,
31 Mar 2017

A new battery has the potential to provide sustainable, high-power energy storage.

A new type of battery, which uses only hydronium ions as the charge, has been developed by researchers at Oregon State University (OSU), USA, offering new possibilities in the field of stationary storage. 

Positively charged hydronium ions (H3O+) are produced when protons are added to water molecules. They can be stored in an electrode material comprising perylenetetracarboxylic dianhydridem (PTCDA) – an organic semiconductor. Dilute sulphuric acid is used as the electrolyte. 

The study, Hydronium-Ion Batteries with Perylenetetracarboxylic Dianhydride Crystals as an Electrode, published in Angewandte Chemie International Edition noted a dilation of the PTCDA’s lattice structure when receiving ions, meaning it was being charged. The movement of these hydronium ions through the electrode with relatively little friction resulted in a high power charge.  

Xiulei Ji, Assistant Professor of Chemistry at OSU, said, ‘Advanced batteries typically rely on intercalation of metal ions in electrodes, where these ions include lithium, sodium and, recently, potassium. Migration of hydronium ions is fundamentally different from the migration of these metal ions because protons could hop from one water molecule to another during diffusion inside the electrodes, which is known as the Grotthuss effect. This potentially provides significantly improved [energy efficiency]'.

Additionally, the batteries could offer a sustainable alternative to current options due to their use of acid an as electrolyte, which is abundantly available and renewable, according to Ji. 

Comparing hydronium-ion batteries to current battery technology, such as lithium-ion batteries, Ji said, ‘Hydronium-ion batteries do not need metal ions as charge carriers, which potentially affords them better sustainability. For example, lithium is relatively rare and its mining is geopolitically challenged.’ 

Until recently, the positively charged ions, or cations, used in batteries were aluminium, alkali metal or alkaline earth metals. ‘No non-metal cations were being considered seriously for batteries [...] Non-metal cations are typically bulky – however, hydronium seems to be an exception,’ Ji said. Hydronium ions are relatively small at a molecular level, similar in size to sodium ions (Na+). 

Potential applications for hydronium-ion batteries include stationary storage – systems for stockpiling energy that are essential for constant use of intermittent power sources, such as solar. However, Ji predicts that the batteries will not be suitable for electric vehicles.