Major breakthroughs set to enhance solid-state lithium battery performance

Chinese scientists have announced two major breakthroughs in solid-state lithium battery technology and resolved longstanding bottlenecks that have hindered commercial adoption of this potentially game-changing technology for the new energy vehicle sector.

The move comes as China tightened its export controls on lithium batteries and synthetic graphite materials, underscoring the nation's strategic efforts in the global electric vehicle supply chain.

Researchers at the Institute of Metal Research under the Chinese Academy of Sciences said they have developed a new material that significantly reduces interfacial resistance and improves ion transport efficiency in solid-state batteries — two key challenges that have limited their practicality.

The team said that flexible batteries made from the new material maintained excellent bending endurance, surviving over 20,000 folding cycles. When used as a polymer electrolyte in composite cathodes, the energy density increased by as much as 86 percent.

"Such a technology could pave the way for safer and more efficient energy solutions in humanoid robots, electric aviation and electric vehicles," it said.

In a separate development, another CAS-led team from the Institute of Physics, in collaboration with other teams, found a new approach that allows all-solid-state batteries to maintain stable electrode contact without relying on bulky external pressure systems. The study was published on Tuesday in the journal Nature Sustainability.

Prototype batteries built using this technique retained excellent cycling stability over hundreds of charge-discharge cycles under standard testing conditions, outperforming comparable designs, it emphasized.

China has been accelerating the development of all-solid-state batteries and expects large-scale road tests of such products between 2025 and 2026, with small-batch installation in EVs starting as early as 2027, said a research note by China International Capital Corp (CICC).

CICC estimates that China's solid-state battery equipment market could reach 2.5 billion yuan ($340 million) by 2027 and grow at a compound annual rate of 122 percent to 27.3 billion yuan by 2030.

Major Chinese EV and battery makers — including CATL, BYD and Gotion High-Tech — have already begun pilot production lines, with mass production targets ranging from hundreds of megawatts to gigawatt levels.

Most leading automakers expect to integrate solid-state batteries into vehicles earlier than expected, as China's technological advantages and policy support continue to accelerate the commercialization.

Ouyang Minggao, an academician at the Chinese Academy of Sciences, said the country's current route for all-solid-state batteries is to develop sulfide-based batteries, which, paired with high-nickel ternary positive and silicon-carbon negative materials, aim to achieve performance targets of 400 watt-hours per kilogram in energy density and life cycles of over 1,000.

"These advances are expected to facilitate the country's small-batch installation of all-solid-state batteries by 2027, with large-scale mass production projected by 2030," said Ouyang, who is also a professor at Tsinghua University.

He said his team has already collaborated with more than 30 related companies to conduct the development and optimization of large-scale models in the vertical field of all-solid-state batteries.

All-solid-state batteries offer higher theoretical energy density and safety, and entail lower costs than lithium-ion batteries that currently dominate the EV sector. Hence, many countries consider them a potentially game-changing technology.

In a further sign of Chinese players' progress in the sector, Sun Huajun, chief technology officer of BYD Lithium Battery Co Ltd — the battery firm for China's largest EV maker BYD — said earlier this year at a conference that the company plans to begin small-scale production of sulfide-based all-solid-state batteries by 2027, and these batteries are expected to be incorporated into its mainstream EV models by 2030.

This timeline places BYD in direct competition with global automakers investing heavily in such batteries, such as Japan's Toyota, which has been ramping up efforts to take a lead in this field.

chengyu@chinadaily.com.cn