Researchers suggest that a disordered rock salt can make rechargeable batteries charge faster.
One of the biggest problems that lithium-ion (li-ion) batteries are facing is slower recharging time. Many applications such as electric vehicles rely on fast charging for their suitability. It can take up to a few hours or overnight to fully recharge EVs, depending on the charging method and amount of charge remaining in the battery. Even in small-scale applications like mobiles and laptops, full charging takes a lot of time.
This is because li-ion batteries are designed so the rechargeable lithium-ion batteries charge only at slower, controlled rates to prevent it from exploding. During fast charging, dendrite-like structures grow inside the battery and induce a short circuit.
To address this issue, researchers from the University of California San Diego (UC San Diego) worked with scientists at Oak Ridge National Laboratory (ORNL) to conduct neutron scattering experiments on a new type of material that could be used to make safer, faster-charging batteries. They conducted this experiment on lithium vanadium oxide (Li3V2O5), a disordered rock salt.
“The two most common materials used to make lithium-ion battery anodes are graphite, which can deliver high energy density but has caused fires in some situations, and lithium titanate, which can charge rapidly and is much less likely to cause fires but has lower energy storage capacity,” said Haodong Liu, a research scientist in professor Ping Liu’s lab at UC San Diego and first author of the paper. “The disordered rock salt material we developed combines the desired properties of both—it is safer, faster-charging, and has a higher energy density.”
During testing, the salt-based anode material was able to deliver more than 40 percent of its energy capacity in just 20 seconds. According to researchers, this is because the rock salt material can cycle two lithium ions in and out of vacant sites within its crystal structure.
“Using neutron diffraction techniques at ORNL enabled us to understand how the ions behave when we applied voltage to the materials,” said Liu. “Neutrons can easily track lithium ions and oxygen atoms inside the rock salt anode, and using the VULCAN instrument at ORNL’s Spallation Neutron Source (SNS) provided the high neutron flux and resolution we needed.”
The research appeared in the journal Nature.