Pressure-induced interfacial contacts and the deformation in all solid-state Li-ion batteries

Significance The notorious dendrite growth and the massive formation of dead Li, rooted in the unfair competition between electrodissolution of Li metal and electrodeposition of Li+ ions with concomitant reduction, degrade the ability of all-solid-state Li-metal batteries (ASSLBs) to reach the desired electrochemical performance. With a theoretical and experimental analysis of the driving forces for dendrite growth, herein, we report the incorporation of piezo-/ferroelectric materials into solid electrolytes can effectively decrease the overpotential directly, thus optimizing the Li+ flux distribution and facilitating an orderly Li deposition and leading to dendrite-free cycling.

Combating Li metal deposits in all-solid-state battery via the piezoelectric and ferroelectric effects

All-solid-state batteries based on solid-state electrolytes (SSE) have attracted considerable attention due to their high capacity and relative safety, compared to conventional batteries based on liquid electrolytes. As ions migrate from the electrodes through solid electrolytes (during charge and discharge cycles of an all-solid-state battery), they exert strains of varying proportions that are distributed across the electrolytes. Here, we show that, for an all-solid-state lithium-oxygen battery based on the SSE lithium amide-borohydride-iodide (LiBH4-LiNH2-LiI), the heterogeneous nature of the electrolyte leads to spatial and temporal variations in the induced strain distributions. The strains associated with discharging are much greater than those induced during charging. These results suggest that charging and discharging processes lead to local strain build-up and possible failure of solid electrolytes. The implications of the results are also discussed for the development of robust-solid-state batteries.

Charge-discharge-induced local strain distributions in a lithium amide-borohydride-iodide [LiBH4-LiNH2-LiI] solid electrolyte

Electrochemo-mechanical response of all solid-state batteries: Finite element simulations supported by image-based 3D reconstruction of X-ray microscopy tomography

Increasing attention has been paid to the safety and efficiency of batteries due to the rapid development and widespread use of electric vehicles. Solid-state batteries have the advantages of good safety, high energy density, and strong cycle performance, and are recognized as the next generation of power batteries. However, solid-state batteries generate large stress changes due to the volume change of electrode materials during cycling, resulting in pulverization and exfoliation of active materials, fracture of solid-electrolyte interface films, and development of internal cracks in solid electrolytes. As a consequence, the cycle performance of the battery is degraded, or even a short circuit can occur. Therefore, it is important to study the stress changes of solid-state batteries or electrode materials during cycling. This review presents a current overview of chemo-mechanical characterization techniques applied to solid-state batteries and experimental setups. Moreover, some methods to improve the mechanical properties by changing the composition or structure of the electrode materials are also summarized. This review aims to highlight the impact of the stress generated inside solid-state batteries and summarizes a part of the research methods used to study the stress of solid-state batteries, which help improve the design level of solid-state batteries, thereby improving battery performance and safety.

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Experimental Investigations on the Chemo-Mechanical Coupling in Solid-State Batteries and Electrode Materials

Solid-state batteries are generally considered to be safer than their liquid-state counterparts due to their decreased potential for fire or short circuiting. The fabrication of solid-state batteries relies on the application of stack crimping pressure that increases the interfacial surface contacts between electrolytes and the electrodes. However, excessive compressive crimping stresses (that occur in cell assembly) can give rise to cracking phenomena that can degrade battery performance and lead to thermal runaway or failure. It is, therefore, important to develop an understanding of failure mechanisms in solid-state Li-ion electrolytes. In this paper, we use a combination of in-situ optical microscopy and Digital Imaging Correlation (strain mapping) techniques to study compressive deformation and cracking phenomena in a novel solid-state Li-ion electrolyte. The stress states associated with the different stages of compressive deformation are also presented along with those due to charge–discharge cycles. The implications of the results are discussed for the material design of robust solid-state Li ion batteries.

Tofunmi Ogunfunmi

Papers

An investigation into compressive deformation and failure mechanisms in a novel Li-ion solid-state electrolyte