Battery Development New sodium-ion battery advance could challenge lithium-ion
Lithium-ion batteries have long since dominated the market. However, sodium-ion battery technology could approach and exceed the performance of Li-ion at a much lower cost and higher efficiency and safety levels.
Now, researchers have created a sodium-ion battery that holds as much energy as some of the lithium-ion battery chemistries that are currently available. This is according to a team from Washington State University (WSU) whose research, in collaboration with the Pacific Northwest National Laboratory (PNNL), could lead to a viable battery technology solution.
The research team claims that its sodium-ion battery technology is capable of delivering a similar capacity to that of some lithium-ion batteries and that it can recharge successfully, retaining 80% of its charging capacity after 1,000 charge cycles. “This is a major development for sodium-ion batteries,” said Dr Imre Gyuk from the US Department of Energy’s Office of Electricity. “There is great interest around the potential for replacing Li-ion batteries with Na-ion in many applications,” she added.
Sodium-ion batteries can also be made more cheaply thanks to the sheer abundance of the inexpensive materials required, such as sodium. Sodium is also very sustainable, making sodium-ion batteries an ideal candidate for large-scale energy storage. In contrast, lithium-ion batteries are made from rare and expensive materials such as cobalt and lithium. As demand for high-level technologies such as electric vehicles and electrical energy storage grows, these materials are going to become harder and more expensive to acquire.
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There is a drawback, however; sodium-ion batteries do not hold as much energy as lithium-ion batteries do, and they can also be challenging to recharge. According to the research team, a key challenge for some of the most promising sodium-ion cathode materials is that a layer of inactive sodium crystals accumulates at the cathode’s surface, inhibiting the flow of sodium ions. This causes the battery to degrade over time. “The key challenge is for the battery to have both high energy density and a good cycle life,” said PhD graduate Junhua Song, the research paper’s principal author.
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In their research, the WSU-PNNL team created a layered metal oxide cathode and a liquid electrolyte with extra sodium ions, creating a saltier solution that resulted in better cathode interaction. This design and electrolyte system facilitated the continued movement of sodium ions, preventing the accumulation of crystals which impedes electricity generation.
“Our research revealed the essential correlation between cathode structure evolution and surface interaction with the electrolyte,” Lin said. The research team believes that their results are the “best… ever reported” for a sodium-ion battery with a layered cathode, demonstrating its viability as a technology comparable to and potentially better than lithium-ion batteries.
The research project was led by Yuehe Lin, a professor in WSU’s School of Mechanical and Materials Engineering, and Xiaolin Li, a senior research scientist at PNNL and was published in the journal, ACS Energy Letters in April.