A new cathode for sodium ion batteries
Researchers using the XSD 12-BM-B beamline at the APS have successfully synthesized a new O3-type layer-structured metal oxide cathode Na(NiCoFeTi)1/4O2 for sodium ion batteries. It delivers a reversible capacity of 116 mA h g−1 in the first cycle and has 93.03% capacity retention after 100 cycles at 1C rate.
Sodium-ion batteries have attracted increasing attention for large-scale energy storage applications because of the natural abundance of sodium resources and potential low cost. However, the lack of high performance cathode materials is one of the major obstacles for the development of current room temperature sodium ion batteries. O3-type layer-structured materials NaTMO2 (TM = transition metals) have been widely investigated as cathode materials for sodium ion batteries (SIBs) inspired by lithium battery systems
High rate capability and long cycle life are challenging goals for the development of room temperature sodium-ion batteries. Here we report a new single phase quaternary O3-type layer-structured transition metal oxide Na(NiCoFeTi)1/4O2 synthesized by a simple solid-state reaction as a new cathode material for sodium-ion batteries. It can deliver a reversible capacity of 90.6 mA h g−1 at a rate as high as 20C. At 5C, 75.0% of the initial specific capacity can be retained after 400 cycles with a capacity-decay rate of 0.07% per cycle, demonstrating a superior long-term cyclability at high current density.
X-ray diffraction and absorption characterization revealed reversible phase transformations and electronic structural changes during the Na+ deintercalation/intercalation process. Ni, Co and Fe ions contribute to charge compensation during charge and discharge. Although Ti ions do not contribute to the charge transfer, they play a very important role in stabilizing the structure during charge and discharge by suppressing the Fe migration. In addition, Ti substitution can also smooth the charge–discharge plateaus effectively, which provides a potential advantage for the commercialization of this material for room temperature sodium-ion batteries.
Ji-Li Yue, Yong-Ning Zhou, Xiqian Yu, Seong-Min Bak, Xiao-Qing Yang and Zheng-Wen Fu, “O3-type Layered Transition Metal Oxide Na(NiCoFeTi)1/4O2 as a High Rate and Long Cycle Life Cathode Material for Sodium Ion Batteries,” Journal of Materials Chemistry A, 2015, Advance Article, DOI: 10.1039/C5TA05769H, Published Online October 9, 2015.