According to Chinese scientists, they have developed a new solid-state battery technology that matches the efficacy of cutting-edge batteries at only 4 percent of the cost.
The majority of EV batteries are lithium-iron phosphate or ternary lithium, and each has its own cost stability and energy density advantages. However, both contain electrolytes in liquid form.
Compared to solids, liquids have a lower energy storage density. Despite advances in liquid battery technology, their size, weight, and potential fire hazard prevent their use in lightweight electric vehicles.
Researchers from the University of Science and Technology of China (USTC) in Anhui province have developed all-solid-state batteries that use solid electrolytes for conduction and are available at a fraction of the price, which bodes well for commercial applications of the technology.
Solid-state batteries have numerous advantages over conventional batteries, including twice the energy density, quicker charging speeds, and no temperature restrictions on charging.
As they are non-combustible, non-corrosive, and leak-proof, these batteries of the next generation are also a safer option for the electric vehicle and energy storage industries. However, expensive production costs have prevented widespread implementation. Solid electrolytes require expensive metals such as lanthanum and cobalt, as well as a high level of precision and dedicated production lines.
A USTC team led by Professor Ma Cheng devised a new solid electrolyte, lithium zirconium oxychloride, to address this issue. According to research published in the peer-reviewed journal Nature Communications last month, its efficacy was found to be comparable to that of advanced sulphide and chloride solid electrolytes, but at only 4% of the price.
A commercially viable solid-state lithium battery electrolyte must exhibit high ionic conductivity, excellent "deformability" or shock absorption capacity, and a price of less than US$50 per kilogramme. No existing electrolyte can meet all of these requirements. In general, ceramic electrolytes lack deformability, while sulphides and chlorides are costly, costing over US$200 per kilogramme.
However, the lithium zirconium oxychloride electrolyte developed by Ma and his colleagues attained an ionic conductivity at room temperature that was more than double the standard required for practical applications. In the meantime, the material's outstanding deformability enabled it to retain its shape under high pressure, thus meeting application requirements.
"The team provided two synthesis routes, one with a raw material cost of $11.6 per kilogramme and the other with a raw material cost of less than $7 per kilogramme. In application tests, a lithium zirconium oxychloride battery required only 12 minutes to charge and maintained stability over 2,000 cycles at room temperature, according to USTC.
The academic community and industrial producers have accelerated their pursuit of this technology of the next generation. However, China's EV manufacturers have opted for semi-solid batteries due to the expensive material and production costs of solid batteries. The Financial Times reported on July 4 that Japanese automaker Toyota, which employs sulphides as solid electrolytes, also intends to commercialise solid-state battery technology.
According to the report, Keiji Kaita, president of Toyota's Carbon Neutral Advanced Engineering Development Centre, stated that their objective was to halve the size, weight, and cost of both liquid and solid batteries. He stated that Toyota had developed techniques to increase battery durability and that the company believed it could produce solid-state batteries with a range of 1,200 kilometres (745 miles) and a charging duration of 10 minutes or less.
China's exports of lithium-ion batteries accounted for nearly 70 percent of global shipments in 2014, so Toyota's initiative will intensify competition in the EV battery market with China.
However, it is not anticipated that Toyota's products will reach the market until at least 2025, with mass production not likely until 2027.
China is poised to make significant strides in the industrialization of solid-state batteries, according to Dong Yang, vice-chairman of the China Electric Vehicle Association, who told a Shanghai-based website in January that China has the world's largest market for new energy vehicles and is a leader in relevant scientific publications.