Solid-state batteries, where the electrolyte consists of a solid material rather than a liquid one, hold massive potential for future energy storage applications, but have been plagued by stability issues that impact their longevity. A new design points to a new solution to this problem, with the team developing a novel electrode material that retains its volume throughout charging to enable the battery to endure hundreds of cycles.
An ability to operate an electric vehicle or smartphone on a solid-state battery instead of today’s lithium-ion architecture could see them run for longer before they need recharging, and require less plug-in time when they do. Their stability issues, however, are related to the movement of lithium ions in and out of the battery electrodes during charging, which causes them to expand and shrink and ultimately alters the chemistry of the device.
An international team of scientists has designed a new electrode for these batteries that is claimed to offer unprecedented stability. The material is made of lithium titanate and lithium vanadium dioxide, ground down into nanometer-sized particles. Used as a battery electrode, this material offers high-capacity, and enables lithium ions to be reversibly inserted and extracted during charging and discharging.
The result is an electrode material that retains the same volume during operation. The scientists have pinned this on a delicate balancing act that takes place as lithium ions exit and vanadium ions migrate from their original positions to fill in these empty spaces.
“When shrinkage and expansion are well balanced, dimensional stability is retained while the battery is charged or discharged, i.e. during cycling,” said Professor Naoaki Yabuuchi of Yokohama National University, Japan, who led the research. “We anticipate that a truly dimensionally invariable material – one that retains its volume upon electrochemical cycling – could be developed by further optimizing the chemical composition of the electrolyte.”
The novel electrode material was put to the test in a solid-state battery cell and performed impressively, with a high capacity of 300 mAh/g, and perhaps most importantly, no degradation over 400 charge and discharge cycles.
“The absence of capacity fading over 400 cycles clearly indicates the superior performance of this material compared with those reported for conventional all-solid-state cells with layered materials," said study author Associate Professor Neeraj Sharma.
The team plans to continue refining the electrolyte to build the kinds of batteries needed to serve electric vehicles, with greater safety and lifespan. This could mean not just electric vehicles the way we see them today, but helping usher in a new era where they charge much faster and cover greater distances.
"This finding could drastically reduce battery costs,” said Yabuuchi. “The development of practical high-performance solid-state batteries can also lead to the development of advanced electric vehicles. In the future, for instance, it may be possible to fully charge an electric vehicle in as little as five minutes.”
The research was published in the journal Nature Materials.
Source: University of New South Wales
