The rate performance of existing lithium-ion battery (LIBS) electrode materials at low temperatures is generally poor, which severely limits their application in winter and cold climate regions. Therefore, there is a great need to develop an electrode material with good electrochemical properties at low temperatures.
Here,Prof. Meilin Liu from Georgia Institute of Technology, Prof. Chunfu Lin from Qingdao University, and Associate Prof. Tao Yuan from University of Shanghai for Science and TechnologyPartially reduced submicron diameter Tinb24O62 (PR-TNO) fibers were successfully synthesized by electrospinning and subsequent calcination at 900 °C in H2 atmosphere for 4 hours, and the crystal structure of the PR-TNO sample resembles Ti2Nb10O29. When used as a Lib anode, pr-tno exhibits fast mass and charge transport characteristics. First, the Reo3-type layered crystal structure of PR-TNO provides ample space for rapid Li+ transport and storage, especially at low temperatures, where it shows significant capacitive behavior.
Secondly, pr-tno expands the layer spacing, which further promotes the transmission of Li+ between layers. Thirdly, the relatively high operating potential of PR-TNO results in a very thin solid electrolyte interface (SEI) film coating on its primary particles, allowing for rapid Li+ transport between the electrolyte and the PR-TNO lattice. Finally, the partially reduced titanium and niobium ions (e.g., Ti3+ and Nb4+) in PR-TNO enhance the electronic conductivity.
Figure 1PR-TNO redox mechanism and electrochemical kinetics
The enhancement of these intrinsic properties gives PR-TNO good electrochemical kinetics at low temperatures. At -20 °C, pr-tno is at 0Provides a high reversible capacity of 313 mAh g-1 at 1C and 83 at 25 °C3%。PR-TNO further shows high magnification capability at -20 °C at 5C versus 0The 5C capacity ratio is 583%, only slightly below 25 °C (5C vs. 0.).The 5C capacity ratio is 607%）。
Excitingly, PR-TNO also exhibits excellent cycling stability, with a maximum volume change of only 79%, resulting in a capacity retention rate of up to 99 after up to 1680 cycles at 5C2%。In addition, the working mechanisms of PR-TNO have been systematically investigated through a variety of state-of-the-art characterizations, including ectothermic in situ XRD, in situ TEM, off-situ XPS, HRTEM, and STEM. The methods and insights gained in this study may be applicable to the structural and compositional design of other high-performance electrodes for cryogenic operation.
Figure 2Li+ storage performance of pr-tno
partially reduced titanium niobium oxide: a high-performance lithium-storage material in a broad temperature range,advanced science2021. doi: 10.1002/advs.202105119