Scientists have created a positive electrode material that does not degrade after multiple charging cycles for the manufacture of durable solid-state batteries (SSBs).
Electric vehicles are often considered our greatest option for replacing traditional automobiles with a more environmentally friendly alternative. However, electric vehicles and other electric vehicles will almost certainly be powered by lithium-ion batteries, which currently do not provide the required performance and durability at an affordable price.
As a result, researchers from Yokohama National University in Japan and UNSW Sydney in Australia developed a new type of positive electrode material with remarkable stability in SSBs.
The material comprises lithium titanate and lithium vanadium dioxide, which have been ball-milled into nanometer-sized particles. This material has a high capacity due to the enormous amount of lithium ions that can be introduced and withdrawn reversibly during the charge and discharge process. In addition, the electrolyte material preserves its volume after charging, allowing the battery to withstand hundreds of cycles.
The researchers investigated this property’s origin and concluded that it is the product of a balance between two distinct processes that occur when lithium ions are inserted or withdrawn from the crystal. First, however, the elimination of lithium ions increases the free volume of the crystal, causing it to decrease.
On the other hand, some vanadium ions move from their initial position to the voids left behind by the lithium ions, gaining a higher oxidation state in the process.
“When shrinkage and expansion are well balanced, dimensional stability is retained while the battery is charged or discharged, i.e., during cycling,” says Professor Naoaki Yabuuchi of Yokohama National University.
“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 new positive electrode material was tested in an all-solid-state cell by mixing it with an appropriate solid electrolyte and a negative electrode. The material functioned admirably, with a capacity of 300 mAh/g and no degradation after 400 charge and discharge cycles.
“The absence of capacity fading over 400 cycles indicates the superior performance of this material compared with those reported for conventional all-solid-state cells with layered materials,” says Associate Professor Neeraj Sharma, co-author of the study.
“This finding could drastically reduce battery costs. Moreover, developing practical high-performance solid-state batteries can also lead to developing advanced electric vehicles.”
Researchers intend to continue improving the electrode material to produce batteries suitable for electric vehicles in terms of pricing, safety, charging speed, and lifespan.
“The development of long-life and high-performance solid-state batteries would solve some of the problems of electric vehicles,” Prof. Yabuuchi says. “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 today in the journal Nature Materials.