Local Li⁺ Framework Regulation of a Garnet-Type Solid-State Electrolyte

Abstract

Garnet-type solid-state electrolytes Li 7 La 3 Zr 2 O 12 (LLZO) for high-energy-density batteries have attracted extensive attention. However, stabilizing the high-conductive cubic phase and improving its ionic conductivity remain challenges of current research. Here, a Ca−W dual-substitution strategy has been designed, and the effect of doping on cubic phase formation and Li + mobility has been investigated thoroughly. The results indicated that the partial substitution of Ca 2+ at the La 3+ site and W 6+ at the Zr 4+ site can effectively stabilize the cubic phase while reducing the endothermic enthalpy during the synthesis. Moreover, Ca−W dual substitution regulates the local Li + framework by increasing Li + occupancy at the 96h site, which can significantly lower the Li + migration barrier and thus improve the ionic conductivity by two orders of magnitude. This work addresses the challenge of stabilizing a highly conductive cubic phase with low-energy consumption and represents a major breakthrough in understanding how to improve the ionic conductivity by regulating local structures.

Grafting of Lithiophilic and Electron‐Blocking Interlayer for Garnet‐Based Solid‐State Li Metal Batteries via One‐Step Anhydrous Poly‐Phosphoric Acid Post‐Treatment

“…The electronic conductivity (σ e ) can be calculated by the formula $${\sigma _{\rm{e}}} = \frac{{{\rm{d}} \times {\rm{I}}}}{{{\rm{A}} \times {\rm{U}}}}\;$$, where d is the LLZTO pellet thickness, I is the steady‐state current, A is the contact area between the LLZTO and the Ag blocking electrode, and U is the applied voltage. As a result, the calculated electronic conductivity of the as‐prepared PPA‐LLZTO (1.2 × 10 −9 S cm −1 ) is one order of magnitude lower than that of pristine LLZTO (4.07 × 10 −8 S cm −1 , consistent with the previous reports [ 48a,b ] ) owing to the electron‐blocking effect of Li‐PPA layer on PPA‐LLZTO. Moreover, as shown in Figure 3i; Figure S14 (Supporting Information), the electron‐blocking effect of PPA‐LLZTO could be maintained at different applied voltages (0.5–4 V) that represent the actual battery operation circumstances.…”

Recent advances in in situ and operando characterization techniques for Li7La3Zr2O12-based solid-state lithium batteries

“…85 As shown in Fig. 11, initially, LZO is formed according to a 2-to-1 epitaxial growth process along the crystallographic orientations of (À111) LZO // (À111) ZrO2 and [211] LZO // [101] ZrO2 at 750 1C. Then, Li and Ga are diffused into LZO layer by layer along the [011] orientation to form Ga-LLZO at 900 1C.…”

“…13b, the calcination process of LLZTO and Ca/W dual-doped LLZO (LLCZWO) are similar. 101 The whole procedure consists of three reaction stages, namely, the formation of La(OH) 3 (251 to B300 1C), La 2 O 2 CO 3 with unreacted ZrO 2 (B3001 to B760 1C) and cubic LLZO (B7601 to 820 1C). Notably, the LLZTO sample shows an additional reaction from Ta 2 O 5 to LiTaO 3 compared to LLCZWO in the second stage.…”

Advances in Solid-State Batteries, a Virtual Issue, Part II

“…To overcome the space limitations of electric vehicles (EVs) and achieve a driving range of over 500 km, solid-state electrolytes have high expectations over organic electrolytes to vastly improve the EVs (Figure ). One of the most significant components in an SSB is the solid-state electrolyte, which has made great advances, especially polymer electrolytes, − metal sulfide electrolytes (i.e., Na 4 P 2 S 6 , Li 6.5 Sb 0.5 Ge 0.5 S 5 I), garnet-type electrolytes, halide electrolytes, and even Li-rich layered oxide compounds . Garnet-type solid electrolytes are promising solid electrolyte candidates due to the high ionic conductivity and stability with elemental Li .…”