Diffusion-Dependent Graphite Electrode for All-Solid-State Batteries with Extremely High Energy Density

Abstract

In all-solid-state batteries, the electrode has been generally fabricated as a composite of active material and solid electrolyte to imitate the electrode of lithium-ion batteries employing liquid electrolytes. Therefore, an efficient protocol to spatially arrange the two components with a scalable method is critical for high-performance all-solid-state batteries. Herein, a design of the all-solid-state electrode is presented for all-solid-state batteries with higher energy density than the typical composite-type electrode. The proposed electrode, composed mostly of the active materials, has a seamless interface between the active materials, which allows interparticle lithium-ion diffusion. Thus, the solid electrolyte can be completely excluded during the electrode manufacturing process, which enables higher flexibility for fabrication protocol by relieving the concerns about (electro)­chemistry related to solid electrolytes. Furthermore, it can dramatically enhance the normalized energy density by increasing the content of the active material in the electrode. This electrode concept provides a meaningful advance toward high-performance all-solid-state batteries.

Rate Limitations in Composite Solid-State Battery Electrodes: Revealing Heterogeneity with Operando Microscopy

“…Kato et al used composite graphite electrodes with two different SEs to show that increased ionic conductivity leads to enhanced rate performance . Additionally, Kim et al demonstrated graphite electrodes with increased energy density by replacing SE/graphite composite electrodes with slurry-cast graphite electrodes without any SE …”

“…17,33 Holtschi et al analyzed cycling voltage traces to show that rate performance improves with increased temperature but is diminished as electrode thickness increases. 34 35 Graphite has proven to be a useful model system to study the spatial inhomogeneity in ionic transport and state-ofcharge (SOC) in LIBs because of the visible color changes that occur within graphite throughout lithiation. Otoyama et al recently used plan-view and cross-sectional microscopy to observe the evolution of gradients in local SOC within graphite composite electrodes throughout cycling.…”

Understanding metal propagation in solid electrolytes due to mixed ionic-electronic conduction

“…Conversely, our work also shows that solid-state batteries with a non-metal anode, such as Si or graphite, will not suffer from M plating in the SE and hence their impressive cycling results cannot be extrapolated to metal anode SSBs. 48 It should be noted that in our work we only focused only on electronic conductivitydriven metal propagation (metal deposition in the SE), and metal may penetrate an SE for a variety of reasons. 49,50 Hence, our results provide an upper limit for experimental observations.…”

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

“…The dense and thick cathodes may be promising candidates to achieve high loading composite cathodes parallel to the practical condition (e.g., 4 mAh cm À2 ). 414 Recently, Zhhiri et al 415 designed dense cathodes and large format solid-state batteries by controlling the crystallographic orientation and interface presentation of CAMs toward halide SEs. Such a concept enables solid-state batteries with enhanced ionic transport across the interfaces and minimized capacity to fade owing to the reduced interfacial contact area.…”

“…The influence of the coating layer on the effective electronic percolation of the composite cathode should also be quantified. The dense and thick cathodes may be promising candidates to achieve high loading composite cathodes parallel to the practical condition (e.g., 4 mAh cm − 2 ) 414 . Recently, Zhhiri et al 415 designed dense cathodes and large format solid‐state batteries by controlling the crystallographic orientation and interface presentation of CAMs toward halide SEs.…”