Ustc researchers propose a new technology route to unlock the potential of all-solid-state lithium batteries

Professor Ma Cheng of the University of Science and Technology of China (USTC) has proposed a new technology route for all-solid-state battery cathode materials, which can significantly increase the amount of active material in the composite cathode, thus more fully realizing the energy density potential of all-solid-state lithium batteries. The research results were published in the internationally renowned academic journal Nature Communications.

Battery technology is one of the core "two-carbon" technologies such as new energy vehicles and energy storage. All-solid lithium battery has become the research focus of the next generation of lithium batteries because it uses non-combustible inorganic solid electrolyte to replace organic liquid electrolyte. Compared with commercial lithium ion battery, it has higher safety and greater space for energy density improvement.

Figure 1: Conductivity of LTC under different conditions. Photo source: Nature Communications

According to the researchers, in order to give full play to the performance of all-solid-state batteries, the cathode material needs to meet at least two conditions: excellent ionic conductivity and good deformability. However, these two points are difficult to achieve in the oxide materials such as lithium cobaltate and lithium iron phosphate, which are currently used in commercial lithium-ion batteries.

Figure 2: Crystal structure and lithium ion migration of LTC. Photo source: Nature Communications

In this study, Ma's team adopted an unconventional material design idea and chose chloride to construct a new cathode material for all-solid-state lithium batteries, lithium titanium chloride.

The study found that lithium titanium chloride is extremely soft, reaching a relative density of more than 86.1 percent after cold pressing, and its room-temperature ion conductivity of up to 1.04 millisiemens per centimeter is much higher than that of the oxide cathode material, even compared with the solid electrolyte material that is mainly responsible for ion transport in batteries. Therefore, the positive electrode of the complex based on lithium titanium chloride can reach the active material load of 95% mass ratio, which is far beyond the limit of the positive electrode of oxide such as lithium iron phosphate and lithium cobalt oxide in all-solid-state batteries.

Figure 3: Electrochemical performance of a single LTC cell. Photo source: Nature Communications

The results show that the cathode material of chloride, represented by lithium titanium chloride, is a very promising positive electrode "candidate" for all-solid-state lithium batteries, which can further release the energy density potential of all-solid-state batteries.

Text source: Xinhua News Agency

Links to relevant papers:

https://www.nature.com/articles/s41467-023-37122-7#Abs1