Scientists from the University of Science and Technology of China (USTC) affiliated with the Chinese Academy of Sciences (CAS) have developed a novel material to manufacture affordable and effective all-solid-state Li batteries.
The study was published in the journal Nature Communications on July 20th, 2021.
Solid electrolytes are considered as key to realizing safe, energy-dense all-solid Li batteries. Yet, these materials are often very costly. However, they are mostly less tolerant to humidity, making their production very costly, noted Prof. Cheng Ma, who headed the USTC researchers in the study.
The researchers designed and produced a material known as Li2ZrCl6 (LZC). The novel material is affordable and shows more tolerance to humidity, performing all strengths of chloride solid electrolyte.
When compared to different kinds of solid electrolytes, the chloride solid electrolyte is observed to have suitable properties of both oxide and sulfide systems, including high ionic conductivity, oxidative stability and deformability. The unusual combination of these benefits has gained wider attention quickly.
The LZC raw material at 50 μm thickness costs only $1.38/m2. This is way cheaper than the chloride system ever known ($23.05/m2), and also stands below the $10/m2 threshold for guaranteeing the cost-competitiveness of all-solid-state batteries.
The LZC is stable in 5% relative humidity conditions, which nullifies the stringent demand for atmospheric conditions during synthesis and storage, such as those needed by sulfide solid electrolytes.
More significantly, the aforementioned benefits in mass production “have been achieved without sacrificing any of the attractive characteristics of chloride solid electrolytes,” added Professor Ma.
The LCZ still holds high ionic conductivity of (0.81 mS cm−1), great compatibility with 4V-class cathodes, and excellent deformability. A cell with LiNi0.8Mn0.1Co0.1O2 cathode and LZC solid electrolyte is capable of delivering a stable specific capacity of 150 mAh g−1 after 200 cycles at 200 mA g−1 without any noticeable fade. This is competitive with the best of all-solid-state cells.
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 performances of Li2ZrCl6 removes a major obstacle to the commercialization of such batteries.
Cheng Ma, Professor, Chinese Academy of Sciences
For additional research, the researchers will work with other 4+ cations, denoted as M. This is mainly to synthesize Li2MCl6 solid electrolyte and make efforts to produce better and less expensive all-solid-state batteries.
Wang, K., et al (2021) A cost-effective and humidity-tolerant chloride solid electrolyte for lithium batteries. Nature Communications. doi.org/10.1038/s41467-021-24697-2.