Electrification of the transportation sector relies on radical re-imagining of energy storage technologies to provide affordable, high energy density, durable and safe systems. Next generation energy storage systems will need to leverage high energy density anodes and high voltage cathodes to achieve the required performance metrics (longer vehicle range, long life, production costs, safety). Solid-state batteries (SSBs) are promising materials technology for achieving these metrics by enabling these electrode systems due to the underlying material properties of the solid electrolyte ( viz. mechanical strength, electrochemical stability, ionic conductivity). Electro-chemo-mechanical degradation in SSBs detrimentally impact the Coulombic efficiencies, capacity retention, durability and safety in SSBs restricting their practical implementation. Solid|solid interfaces in SSBs are hot-spots of dynamics that contribute to the degradation of SSBs. Characterizing and understanding the processes at the solid|solid interfaces in SSBs is crucial towards designing of resilient, durable, high energy density SSBs. This work provides a comprehensive and critical summary of the SSB characterization with a focus on in situ and operando studies. Additionally, perspectives on experimental design, emerging characterization techniques and data analysis methods are provided. This work provides a thorough analysis of current status of SSB characterization as well as highlights important avenues for future work.
more »
« less
Kinetics or Transport: Whither Goes the Solid-State Battery Cathode?
Solid-state batteries (SSBs) hold the potential to enhance the energy density, power density, and safety of conventional lithium-ion batteries. The theoretical promise of SSBs is predicated on the mechanistic design and comprehensive analysis of various solid–solid interfaces and microstructural features within the system. The spatial arrangement and composition of constituent phases (e.g., active material, solid electrolyte, binder) in the solid-state cathode dictate critical characteristics such as solid–solid point contacts or singularities within the microstructure and percolation pathways for ionic/electronic transport. In this work, we present a comprehensive mesoscale discourse to interrogate the underlying microstructure-coupled kinetic-transport interplay and concomitant modes of resistances that evolve during electrochemical operation of SSBs. Based on a hierarchical physics-based analysis, the mechanistic implications of solid–solid point contact distribution and intrinsic transport pathways on the kinetic heterogeneity is established. Toward designing high-energy-density SSB systems, the fundamental correlation between active material loading, electrode thickness and electrochemical response has been delineated. We examine the paradigm of carbon-binder free cathodes and identify design criteria that can facilitate enhanced performance with such electrode configurations. A mechanistic design map highlighting the dichotomy in kinetic and ionic/electronic transport limitations that manifest at various SSB cathode microstructural regimes is established.
more »
« less
- Award ID(s):
- 2041499
- NSF-PAR ID:
- 10336716
- Date Published:
- Journal Name:
- ACS Applied Materials & Interfaces
- ISSN:
- 1944-8244
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract Solid‐state batteries (SSBs), utilizing a lithium metal anode, promise to deliver enhanced energy and power densities compared to conventional lithium‐ion batteries. Penetration of lithium filaments through the solid‐state electrolytes (SSEs) during electrodeposition poses major constraints on the safety and rate performance of SSBs. While microstructural attributes, especially grain boundaries (GBs) within the SSEs are considered preferential metal propagation pathways, the underlying mechanisms are not fully understood yet. Here, a comprehensive insight is presented into the mechanistic interactions at the mesoscale including the electrochemical‐mechanical response of the GB‐electrode junction and competing ion transport dynamics in the SSE. Depending on the GB transport characteristics, a highly non‐uniform electrodeposition morphology consisting of either cavities or protrusions at the GB‐electrode interface is identified. Mechanical stability analysis reveals localized strain ramps in the GB regions that can lead to brittle fracture of the SSE. For ionically less conductive GBs compared to the grains, a crack formation and void filling mechanism, triggered by the heterogeneous nature of electrochemical‐mechanical interactions is delineated at the GB‐electrode junction. Concurrently, in situ X‐ray tomography of pristine and failed Li7La3Zr2O12(LLZO) SSE samples confirm the presence of filamentous lithium penetration and validity of the proposed mesoscale failure mechanisms.
-
more » « less
Abstract The manufacturing process of all-solid-state batteries necessitates the use of polymer binders. However, these binders, being ionic insulators by nature, can adversely affect charge transport within composite cathodes, thereby impacting the rate performance of the batteries. In this work, we aim to investigate the impact of fabrication methods, specifically the solvent-free dry process versus the slurry-cast wet process, on binder distribution and charge transport in composite cathodes of solid-state batteries. In the dry process, the binder forms a fibrous network, while the wet process results in binder coverage on the surface of cathode active materials. The difference in microstructure leads to a notable 20-fold increase in ionic conductivity in the dry-processed cathode. Consequently, the cells processed via the dry method exhibit higher capacity retention of 89% and 83% at C/3 and C/2 rates, respectively, in comparison to 68% and 58% for the wet-processed cells at the same rate. These findings provide valuable insights into the influence of fabrication methods on binder distribution and charge transport, contributing to a better understanding of the binder’s role in manufacturing of all-solid-state batteries.
-
Solid-state-batteries (SSBs) present a promising technology for next-generation batteries due to their superior properties including increased energy density, wider electrochemical window and safer electrolyte design. Commercialization of SSBs, however, will depend on the resolution of a number of critical chemical and mechanical stability issues. The resolution of these issues will in turn depend heavily on our ability to accurately model these systems such that appropriate material selection, microstructure design, and operational parameters may be determined. In this article we review the current state-of-the art modeling tools with a focus on chemo-mechanics. Some of the key chemo-mechanical problems in SSBs involve dendrite growth through the solid-state electrolyte (SSE), interphase formation at the anode/SSE interface, and damage/decohesion of the various phases in the solid-state composite cathode. These mechanical processes in turn lead to capacity fade, impedance increase, and short-circuit of the battery, ultimately compromising safety and reliability. The article is divided into the three natural components of an all-solid-state architecture. First, modeling efforts pertaining to Li-metal anodes and dendrite initiation and growth mechanisms are reviewed, making the transition from traditional liquid electrolyte anodes to next generation all-solid-state anodes. Second, chemo-mechanics modeling of the SSE is reviewed with a particular focus on the formation of a thermodynamically unstable interphase layer at the anode/SSE interface. Finally, we conclude with a review of chemo-mechanics modeling efforts for solid-state composite cathodes. For each of these critical areas in a SSB we conclude by highlighting the key open areas for future research as it pertains to modeling the chemo-mechanical behavior of these systems.more » « less
-
more » « less
Abstract With the increasing use of Li batteries for storage, their safety issues and energy densities are attracting considerable attention. Recently, replacing liquid organic electrolytes with solid‐state electrolytes (SSE) has been hailed as the key to developing safe and high‐energy‐density Li batteries. In particular, Li1+
x Alx Ti2−x (PO4)3(LATP) has been identified as a very attractive SSE for Li batteries due to its excellent electrochemical stability, low production costs, and good chemical compatibility. However, interfacial reactions with electrodes and poor thermal stability at high temperatures severely restrict the practical use of LATP in solid‐state batteries (SSB). Herein, a systematic review of recent advances in LATP for SSBs is provided. This review starts with a brief introduction to the development history of LATP and then summarizes its structure, ion transport mechanism, and synthesis methods. Challenges (e.g., intrinsic brittleness, interfacial resistance, and compatibility) and corresponding solutions (ionic substitution, additives, protective layers, composite electrolytes, etc.) that are critical for practical applications are then discussed. Last, an outlook on the future research direction of LATP‐based SSB is provided.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acsami.2c04962
