Bi-functional electrolyte boosts cell energy density
Oak Ridge National Laboratory (ORNL) researchers have developed a battery chemistry that challenges an enduring belief that the three main components of a battery—the positive cathode, negative anode and ion-conducting electrolyte—act independently and can only perform a singular job in the cell.
The electrolyte, which embodies the team's battery design, has dual functions—serving not only as an ion conductor but also as a cathode supplement. The cooperative chemistry, enabled by the use of an ORNL-developed solid electrolyte, delivers an extra boost to the batterys capacity and extends the lifespan of the device.
This bi-functional electrolyte revolutionizes the concept of conventional batteries and opens a new avenue for the design of batteries with unprecedented energy density, explained ORNL's Chengdu Liang.
When ORNL researchers incorporated a solid lithium thiophosphate electrolyte into a lithium-carbon fluoride battery, the device generated a 26 per cent higher capacity than what would be its theoretical maximum if each component acted independently.
The team demonstrated the new concept in a lithium carbon fluoride battery, considered one of the best single-use batteries because of its high energy density, stability and long shelf life. When ORNL researchers incorporated a solid lithium thiophosphate electrolyte, the battery generated a 26 per cent higher capacity than what would be its theoretical maximum if each component acted independently. The increase is caused by the cooperative interactions between the electrolyte and cathode.
As the battery discharges, it generates a lithium fluoride salt that further catalyses the electrochemical activity of the electrolyte, Liang said. This relationship converts the electrolyte—conventionally an inactive component in capacity—to an active one.
The improvement in capacity could translate into years or even decades of extra life, depending on how the battery is engineered and used. Longer-lived disposable batteries are in demand for applications such as such as artificial cardiac pacemakers, radiofrequency identification devices, remote keyless system, and sensors, where replacing or recharging a battery is not possible or desirable.
If you have a pacemaker, you dont want to undergo surgery every 10 years to replace the battery, Liang said. What if a battery could last 30 to 50 years? Our fundamental research is opening up that possibility through a new design mechanism.
ORNL is managed by UT-Battelle for the Department of Energy's Office of Science.
- Paul Buckley
EE Times Europe
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