Researchers from the University of Science and Technology of China (USTC) have designed a material to make solid-state lithium-ion batteries cheaper and more effective.
The team identified different types of solid electrolytes, but found chloride solid electrolytes exhibited the desirable characteristics of both sulfide and oxide systems, including high ionic conductivity, deformability and oxidative stability.
The team designed and synthesised the material, Li2ZrCl6 (LZC), which boasts low materials cost and excellent humidity tolerance— challenges that have hindered the mass production of solid electrolytes.
An article outlining the research was published in the science journal Nature Communications.
The raw material cost of LZC at 50μm thickness is $1.38/m2, compared to the cheapest chloride system in the literature ($23.05/m2), and below the $10/m2 threshold for ensuring the cost competitiveness of all-solid-state batteries, said the researchers.
Furthermore, LZC is stable in an atmosphere with 5% relative humidity, so the strict requirements for atmosphere during synthesis and storage, like those for sulfide solid electrolytes, are no longer needed.
LZC possesses high ionic conductivity (0.81 mS cm-1) and is compatible with 4V-class cathodes.
A cell with a LiNi0.8Mn0.1Co0.1O2 cathode and a LZC solid electrolyte delivered a stable specific capacity of about 150mAh g-1 after 200 cycles at 200 mA g-1 without considerable fade, said the researchers.
More importantly, the above advantages in mass production have been achieved without sacrificing any of the attractive characteristics of chloride solid electrolytes, said professor Ma Zhiming.
Zhiming said: "All-solid-state Li batteries play an important role in achieving the goal of 'peak carbon dioxide emissions' and 'carbon neutrality'.
"The achievement of both cost-effectiveness and high performance of Li2ZrCl6 removes a major obstacle to the commercialization of such batteries."
The team will now try other 4+ cations, denoted as M, to synthesize Li2MCl6 solid electrolytes, and strive to make both better and more affordable all-solid-state batteries.