Porous Mixed Ionic Electronic Conductor Interlayers for Solid-State Batteries

Abstract

Rechargeable solid-state batteries (SSBs) have emerged as the next-generation energy storage device based on lowered fire hazard and the potential of realizing advanced battery chemistries, such as alkali metal anodes. However, ceramic solid electrolytes (SEs) generally have limited capability in relieving mechanical stress and are not chemically stable against body-centered cubic alkali metals or their alloys with minor solute elements (β-phase). Swelling-then-retreating of β-phase often causes instabilities such as SE fracture and corrosion as well as the loss of electronic/ionic contact, which leads to high charge-transfer resistance, short-circuiting, etc. These challenges have called for the cooperation from other classes of materials and novel nanocomposite architectures in relieving stress and preserving essential contacts while minimizing detrimental disruptions. In this review, we summarize recent progress in addressing these issues by incorporating other classes of materials such as mixed ion-electron conductor (MIEC) porous interlayers and ion-electron insulator (IEI) binders, in addition to SE and metals (e.g., β-phase and current collectors) that are the traditional SSB components. In particular, we focus on providing theoretical interpretations on how open nanoporous MIEC interlayers manipulate β-phase deposition and stripping behavior and thereby suppress such instabilities, referring to the fundamental thermodynamics and kinetics governing the nucleation and growth of the β-phase. The review concludes by describing avenues for the future design of porous MIEC interlayers for SSBs.

20 μ m-Thick Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 -Based Flexible Solid Electrolytes for All-Solid-State Lithium Batteries

“…Substituting lithium metal for graphite anode is considered to be a promising strategy [1][2][3][4][5]. However, inferior cycling stability, lithium dendrite growth and safety risk hamper the developments of lithium metal batteries due to the use of organic liquid electrolytes [6][7][8][9].…”

Revealing Li dynamics in mixed ionic-electronic conducting interlayer of all-solid-state batteries

“…Especially, the electron insulation is regarded critical in avoiding the Li 0 deposition at the interlayer|SE interface. 17 However, some reported interlayers, like the silvercarbon composite 4 and graphite 5,16 , are typical mixed ionic-electronic conductors (MIEC) 18 , contrary to the above requirements. The graphite interlayer can enable a Li 0 /Li 0 symmetric cell to operate at a remarkable critical current density (CCD) of 10 mA cm −2 (Fig.…”

Challenges, interface engineering, and processing strategies toward practical sulfide‐based all‐solid‐state lithium batteries

“…Every 1 mAh cm À2 of reversible areal capacity in the ASSLBs corresponds to plating and stripping fully dense metallic lithium with an approximately 5 μm in thickness. 101 Since the lack of fluidity for sulfide SEs, such dynamic volume variation trend to cause the void formation and physical contact loss. Moreover, such void evolution is highly related to the lithium dendrite growth, and this will be further delved into in Section 2.3.…”

“…The total volume of the lithium metal anodes experiences swelling and shrinkage during cell operation. Every 1 mAh cm − 2 of reversible areal capacity in the ASSLBs corresponds to plating and stripping fully dense metallic lithium with an approximately 5 μm in thickness 101 . Since the lack of fluidity for sulfide SEs, such dynamic volume variation trend to cause the void formation and physical contact loss.…”

“…As a result, the 0.6 Ah pouch cell exhibited stable CE over 99.8% and excellent capacity retention (1000 cycles, at 0.5°C), as well as high‐energy density (>900 Wh L −1 ) (Figure 10D). Subsequently, Kim et al 101 summarized this design as a porous mixed ionic electronic conductor (MIEC) interlayer, in which a 3D open‐porous architecture is used to host swelling of metallic lithium and enable fast stress relaxation. However, owing to the inherent difference of lithium dendrite mechanisms and interfacial properties in ASSLBs and liquid LiBs, the design strategies of such porous MIEC interlayer should be distinguished from that of the 3D MIEC framework in liquid LiBs in terms of porosity, size of pores, and solubility of metallic elements.…”