The deployment of Li‐garnet Li7La3Zr2O12 (LLZO) solid‐state electrolytes in solid‐state batteries is severely hampered by their poor wettability with metallic Li. In this work, Sb is presented as a compelling interfacial layer allowing superior wetting of Li onto a LLZO surface, resulting in a remarkably low Li/LLZO interfacial resistance of 4.1(1) Ω cm2. An atomistic insight into Sb‐coated LLZO interface using soft and hard X‐ray photoelectron spectroscopy and focused ion beam time‐of‐flight secondary ion mass spectrometry shows the formation of a Li‐Sb alloy as an interlayer. It is determined that the Li/Sb‐coated LLZO/Li symmetrical cells exhibit a high critical current density of up to 0.64 mA cm−2 and low overpotentials of 40–50 mV at a current density of 0.2 mA cm−2 without applying external pressure. The electrochemical performance of Sb coated‐LLZO pellets is also assessed with an intercalation‐type V2O5 cathode. Li/Sb‐coated‐LLZO/V2O5 full cells deliver stable capacities of around 0.45 mAh cm−2, with a peak current density of 0.3 mA cm−2.

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Parameters for energy density calculations, charging process schematics, calculated gravimetric and volumetric energy densities, calculated current densities vs pore sizes (PDF)

While significant progress has been achieved in the field of Li‐garnet solid‐state batteries, their further development, is hindered by the formation of cavities at the Li7La3Zr2O12 (LLZO)/Li interface at practically relevant current densities and areal capacities exceeding 1 mA cm−2 and 1 mAh cm−2. As a result, the cells exhibit limited cycling stability due to the inhomogeneous distribution of the applied current density, and therefore, the formation of Li dendrites. Another aspect of high importance is associated with the development of the fabrication methodology of thin LLZO electrolytes for achieving the high energy density of Li‐garnet solid‐state batteries. To contribute to these two challenging problems, in this work, a facile intermediate‐stage sintering method of 50‐µm thin and porous LLZO membranes with a mean pore size of 2.5 µm is presented. The employment of such porous LLZO membranes not only provides an effective means of mitigating the formation of voids at the LLZO/Li interface due to the increased LLZO/Li surface area, but also maximizes achievable energy densities. It is demonstrated that fabricated porous LLZO membranes exhibit long cycling stability of over 1480 h at a current density of 0.5 mA cm−2.

Li dendrites form inLi 7 La 3 Zr 2 O 12 (LLZO) solid electrolytes due to intrinsic volume changes of Li and the appearance of voids at the Li metal/LLZO interface. Bilayer dense-porous LLZO membranes make for a compelling solution of this pertinent challenge in the field of Li-garnet solid-state batteries (SSB). Lithium is thus stored in the pores of the LLZO, thereby avoiding i) dynamic changes of the anode volume and ii) the formation of voids during Li stripping due to increased surface area of the Li/LLZO interface. The dense layer then additionally reduces the probability of short circuits during cell charging. In this work, a method for producing such bilayer membranes utilizing sequential tape-casting of porous and dense layers is reported. The minimum attainable thicknesses are 8-10 μm for dense and 32-35 μm for porous layers, enabling gravimetric and volumetric energy densities of Li-garnet SSBs of 279 Wh kg −1 and 1003 Wh L −1 , respectively. Bilayer LLZO membranes in symmetrical cell configuration exhibit high critical current density up to 6 mA cm −2 and cycling stability of over 160 cycles at a current density of 0.5 mA cm −2 at an areal capacity limitation of 0.25 mAh cm −2 .

Lithiated Nb, Al, or Ti metal oxide interlayers improve the LiCoO2/LLZO interface, whereby the Li–Nb–O interlayer exhibits the highest performance.

Energy storage is one of the biggest challenges in our way before switching to sustainable energy resources. Batteries can be a viable solution to this challenge if “better” batteries with higher energy density, improved stability and cheap price can be realized. Lithium-oxygen batteries have become popular recently as they can theoretically offer much higher energy densities compared the widely used Li-ion or Ni-Mh batteries. However, realizing Li-O2 batteries is no easy task, because of the electrolyte decomposition, cathode degradation and anode related problems which were intensively studied in recent years.1,2 These aforementioned problems come together to complicate the electrochemistry taking place inside the cell, consecutively over-potential, low cycling life and poor current rate responses are observed. In this study thin film coatings of TiO2 are fabricated using atomic layer deposition technique (ALD) on multiwalled carbon nanotubes (MWCNT) and these composites were used as cathode for Li-O2 battery. (Fig.1) Such a structure eliminates the direct interaction of carbon surface with electrolyte molecules and prevents the degradation of carbon cathode without sacrificing the high energy density carbon provides. TiO2 was chosen as the coating material, since in a recent study by Thotiyl et. al. a thin surface film of TiO2 was shown to increase the oxygen reduction and evolution reactions activity of the TiC cathodes.3 The electrochemical properties of the prepared composites and the comprehensive analysis of their effect on degradation mechanisms will be discussed in this presentation. References Thotiyl, M. M. O., Freunberger, S. A., Peng, Z., Bruce, P. G., J. Am. Chem. Soc. 2013, 135, 494. McCloskey, B. D., Speidel, A., Scheffler, R., Miller, D. C., Viswanathan, V., Hummelshøj, J. S., Nørskov, J. K., Luntz, A. C., J. Phys. Chem. Lett., 2012, 3, 997. Thotiyl, M. M. O., Freunberger, S. A., Peng Z., Chen, Y., Liu, Z., Bruce, P. G., Nat. Mater. 2013, 12, 1050. Figure 1