New material for solid lithium batteries

QINGDAO — Chinese researchers have developed a new cathode material that could significantly increase the number of times all-solid-state lithium batteries can be recharged, potentially enhancing their commercial viability.

The study, recently published in the journal Nature Energy, was conducted by a team from the Chinese Academy of Sciences' Qingdao Institute of Bioenergy and Bioprocess Technology in Shandong province.

The team said that all-solid-state lithium batteries, which use solid electrolytes, are less prone to leakage and combustion than conventional liquid lithium-ion batteries, which are widely used in electric vehicles, mobile phones and computers.

Ju Jiangwei, a researcher at the institute and the study's corresponding author, said the new cathode material provides all-solid-state lithium batteries with high conductivity, high specific discharge capacity, minimal volume change, high energy density and an extended cycle life compared to previous versions.

The new cathode material, which has yet to be named, offers significant safety and performance improvements. Ju said it achieves electronic and ionic conductivity more than 1,000 times higher than traditional battery cathode materials, which makes for smooth charge and discharge cycles without the need for conductive additives, simplifying the battery preparation process and enhancing the battery's overall performance.

Ju said the new material's 1.2 percent volume change during charge and discharge is more conducive to maintaining battery stability than traditional materials, which experience a volume change of over 2.6 percent. Even after 5,000 charge and discharge cycles, the new material retains 80 percent of its initial capacity.

The new material also provides a battery energy density of up to 390 watt-hours per kilogram, which is almost a third more than the most advanced lithium-ion batteries currently on the market.

According to the research team, all-solid-state lithium batteries represent a new generation of energy storage technology with significant potential in the power battery market. Their successful commercialization could provide strong momentum for China's new energy automobile industry and low-altitude economy. They can also store electricity generated from wind and solar energy, supporting China's "dual carbon "goals of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060, and promoting a green and low-carbon economic transition.

The researchers initially took inspiration from a 2008 paper by Nobel chemistry laureate John Bannister Goodenough, which suggested the parent material for the new cathode could have excellent ionic conductivity. Due to its complex elemental composition, the team spent two years synthesizing it.

"Contrary to our expectations, the ionic conductivity of this material is low, while the electronic conductivity is high," Ju said. "We first improved the ionic conductivity by doping it with germanium, then enhanced the electronic conductivity by replacing sulfur with selenium, and finally obtained the new material."

The team also discovered that substituting germanium with more abundant and cheaper silicon could significantly reduce production costs, facilitating the commercialization of all-solid-state lithium batteries.

"We are currently preparing this material in small batches and expect to achieve large-scale production in two to three years," Ju said. "In terms of cost, we hope to develop a new material with less lithium in the future. If successful, the cost of sulfide solid-state lithium batteries could be reduced to 30 percent of that of liquid lithium batteries."

Ju said the research team will also focus on the recycling of all-solid-state lithium batteries in future studies.

Xinhua