Direct View on the Origin of High Li⁺ Transfer Impedance in All‐Solid‐State Battery

Abstract

Large interfacial resistance plays a dominant role in the performance of all-solid-state lithium-ion batteries. However, the mechanism of interfacial resistance has been under debate. Here, the Li + transport at the interfacial region is investigated to reveal the origin of the high Li + transfer impedance in a LiCoO 2 (LCO)/LiPON/Pt all-solid-state battery. Both an unexpected nanocrystalline layer and a structurally disordered transition layer are discovered to be inherent to the LCO/LiPON interface. Under electrochemical conditions, the nanocrystalline layer with insufficient electrochemical stability leads to the introduction of voids during electrochemical cycles, which is the origin of the high Li + transfer impedance at solid electrolyte-electrode interfaces. In addition, at relatively low temperatures, the oxygen vacancies migration in the transition layer results in the formation of Co 3 O 4 nanocrystalline layer with nanovoids, which contributes to the high Li + transfer impedance. This work sheds light on the mechanism for the high interfacial resistance and promotes overcoming the interfacial issues in all-solid-state batteries.

Elucidating the charge-transfer and Li-ion-migration mechanisms in commercial lithium-ion batteries with advanced electron microscopy

“…As mentioned earlier, TEM combined with in situ techniques can be used to directly determine the interfacial transport performance of lithium ions based on changes in the contrast of images obtained by TEM, the interfacial distribution of Li ions determined by EELS, and the interfacial potential and interfacial electric field evaluated by EH and DPC. Yang et al examined the interfacial potential of an LiCoO2/lithium phosphorus oxynitride (LiPON)/Pt all-solid-state battery by EH [210], and found that both the LCO-LiPON nanocrystalline interfacial layer and the structurally disordered transition layer were inherent, and the insufficient electrochemical stability of the nanocrystalline layer led to interstices and increased impedance during electrochemical cycling. Yamamoto et al also examined Au/LCO/Li1+x+yAlyTi2−ySixP3−xO12 (LATSPO)/Pt by EH, and found that the reversible resistance that was probably caused by the space charge layer was concentrated on the cathode-electrolyte interface (Figure 8(b)) [115,116].…”

Biomimicry-inspired fish scale-like Ni3N/FeNi3N/NF superhydrophilic/superaerophobic nanoarrays displaying high electrocatalytic performance

“…S10b † depict the fitted Nyquist plots of the prepared catalyst samples. Unlike the other samples, the Nyquist plot of the Ni 3 N/FeNi 3 N/NF sample consists of two semi-circles, where the resistance R 1 at higher frequencies is related to the interfacial resistance, [56][57][58][59][60] while the lower frequency depends on the R ct . In addition, the constant-phase elements CPE 1 and CPE 2 both represent C dl , and the Nyquist plot further proves that the Ni 3 N/FeNi 3 N/NF sample has the characteristics of porosity and heterostructure.…”

Layer-by-Layer Assembly of CeO2–x@C-rGO Nanocomposites and CNTs as a Multifunctional Separator Coating for Highly Stable Lithium–Sulfur Batteries

“…Further, EIS was measured to evaluate the impact of functional separators on the electrochemical reaction kinetics within the batteries (Figure 5d and see the equivalent circuit in Figure S10). Once assembled, the batteries using different separators show roughly the same electrolyte resistance (R e ) and diffusion resistance (W o , Warburg impedance), 54,55 whereas the charge-transfer resistance (R ct ) of batteries decreases in the order of using PP, CNT, CeO 2−x @C/CNT, and CeO 2−x @C-rGO/CNT separators, which can be attributed to the improved charge transfer to varying degrees enabled by different coating layers on top of the PP separator to facilitate sulfur redox reactions. After cycling, attributing to irreversible deposition of Li 2 S 2 /Li 2 S and S, an extra semicircle representing the interfacial resistance R f appears at the highfrequency region of EIS plots for all the four batteries.…”