Intermediate‐Stage Sintered LLZO Scaffolds for Li‐Garnet Solid‐State Batteries

Abstract

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.

Garnet-Based Solid-State Li Batteries with High-Surface-Area Porous LLZO Membranes

“…These values align with those reported in existing literature, affirming consistency. 34 To explore the electrochemical behavior of self-standing porous LLZO membranes, symmetric Li/LLZO/Li cells were fabricated using the cold isostatic pressing of Li onto an LLZO membrane at ca. 71 MPa.…”

“…Recently, we have introduced a novel method for fabricating porous LLZO membranes known as intermediate-stage sintering. 34 This approach involves terminating the sintering process before full densification of the ceramics. A notable advantage of this process is the ability to achieve small pore sizes in LLZO ceramics without the need for pore formers.…”

Design Strategies for Anodes and Interfaces Toward Practical Solid‐State Li‐Metal Batteries

“…In this regard, attempts have been made to fabricate thick (>10 μm) layers of porous solid electrolytes. [113,114] Bao et al successfully prepared a self-standing LLZTO ceramic skeleton with a thickness of 10−15 μm using a tape-casting method. [113] Further, Okur et al fabricated a porous LLZO scaffold with intermediate-stage sintering, without the use of any pore formers.…”

“…[113] Further, Okur et al fabricated a porous LLZO scaffold with intermediate-stage sintering, without the use of any pore formers. [114] Although these studies demonstrated that porous solid electrolytes can be produced, the porosity of the solid electrolyte would have to be much higher to fully utilize the benefits of 3D porous structures. Moreover, because solid electrolytes are theoretically not electron conductors, they should be coated with conductive agents to facilitate electrochemical reactions at the solid-electrolyte surface and reversibly store Li metal during charge and discharge.…”

Porous Ga0.25Li6.25La3Zr2O12 frameworks by gelcasting–reaction sintering for high-performance hybrid quasi-solid lithium metal batteries

“…Furthermore, before assembling the battery, a small amount of lithium metal must be vapor-deposited into the surface pores of the porous LLZO membrane to enhance the contact between the porous LLZO and the lithium anode. [28][29][30] The treatment process mentioned exhibits a high level of complexity, thereby hindering the advancement of porous LLZO-based SSLMBs.…”