posted on 2024-01-30, 23:17authored byJie Wang, Wen Yan, Jing Jing Fu, Lin Wang, Bo Liu
Solid electrolyte interphase (SEI) plays a critical role
in the
performance of lithium-ion batteries (LIBs). In contrast to the clear
interface between the traditional consecutive electrode materials
and SEI, ionic polyoxometalates (POMs) as electrode could bilaterally
diffuse with SEI and form a blending interface for superior electrochemical
performance. POMs have recently aroused much interest as electrode
materials in LIBs due to their structural flexibility, high capacity,
and cycling stability. However, the interface evolution between POM-based
electrodes and SEI, which is critical for Li+ ion transportation,
has rarely been explored. Herein, we choose Li10[V12B18O60H6] (LVB) as an example
to investigate the formation and structural evolution of the electrode–electrolyte
interface. Time-of-flight secondary ion mass spectrometry together
with X-ray photoelectron spectroscopy demonstrates the evolution of
a blending layer at the interface containing typical SEI components,
a polyanion from LVB and a phosphate anion from decomposition products
of LiPF6. In the blending layer, ion migration takes place
between the P-related inorganic species and the polyanion during the
Li+ insertion/extraction reaction. Such a compatible blending
layer favors Li+ transportation and the reversibility of
the redox reactions, as supported by a series of electrochemical analyses.
This work provides detailed insights into understanding the interface
evolution of the LVB electrode and demonstrates the importance of
interfacial engineering to induce proper interface layers in the development
of high-performance POM-based electrodes for LIBs.