Engineering topics

Zhu, Juner

Publications and source records attributed to Zhu, Juner.

3 records

DOE OSTI2023

Nondestructively Visualizing and Understanding the Mechano-Electro-chemical Origins of “Soft Short” and “Creeping” in All-Solid-State Batteries

All-solid-state Li-metal batteries (ASLMBs) represent a significant breakthrough in the quest to overcome limitations associated with traditional Li-ion batteries, particularly in energy density and safety aspects. However, widespread implementation is stymied due to a lack of profound understanding of the complex mechano-electro-chemical behavior of Li metal in the ASLMBs. Herein, operando neutron imaging and X-ray computed tomography (XCT) are leveraged to nondestructively visualize Li behaviors within ASLMBs. This approach offers real-time observations of Li evolutions, both pre- and post- occurrence of a “soft short”. The coordination of 2D neutron radiography and 3D neutron tomography enables charting of the terrain of Li metal deformation operando. Concurrently, XCT offers a 3D insight into the internal structure of the battery following a “soft short”. Despite the manifestation of a “soft short”, the persistence of Faradaic processes is observed. To study the elusive “soft short”, phase field modeling is coupled with electrochemistry and solid mechanics theory. The research unravels how external pressure curbs dendrite growth, potentially leading to dendrite fractures and thus uncovering the origins of both “soft” and “hard” shorts in ASLMBs. Furthermore, by harnessing finite element modeling, it dive deeper into the mechanical deformation and the fluidity of Li metal.

25 ENERGY STORAGE↗

DOE OSTI2023

Taming Metal–Solid Electrolyte Interface Instability via Metal Strain Hardening

Abstract Solid-state lithium metal batteries have emerged as a promising technology for electric vehicles due to their high specific energy and safety potential. Obtaining intimate contact between Li and electrolyte during cell fabrication, however, remains challenging. Adequate fabrication pressure is required to promote close contact, but this pressure can cause Li deformation and penetration into the electrolyte, resulting in poor battery performance. Here, a strategy for addressing this problem is presented by incorporating 3 at% Mg into Li. Unlike pure Li which obeys the Voce hardening law and allows unconstrained deformation, Li–Mg alloy follows the Swift hardening law and strengthens with strain under compression stress. Because of the constrained deformation of Li–Mg, intimate contact with solid electrolytes is possible even at high fabrication pressure (50–65 MPa), resulting in high critical current densities. These findings underscore the importance of understanding Li metal deformation properties to improve solid-state battery performance.

25 ENERGY STORAGE↗

DOE OSTI2023

Unveiling the Mechanical and Electrochemical Evolution of Nanosilicon Composite Anodes in Sulfide-Based All-Solid-State Batteries

The utilization of silicon anodes in all-solid-state lithium batteries provides good prospects for facilitating high energy density. However, the compatibility of sulfide solid-state electrolytes (SEs) with Si and carbon is often questioned due to potential decomposition. Here, in this paper, operando X-ray absorption near-edge structure (XANES) spectroscopy, ex situ scanning electron microscopy (SEM), and ex situ X-ray nanotomography (XnT) are utilized to investigate the chemistry and structure evolution of nano-Si composite anodes. Results from XANES demonstrate a partial decomposition of SEs during the first lithiation stage, which is intensified by the presence of carbon. Nevertheless, the performances of first three cycles in Si–SE–C are stable, which proves that the generated media is ionically conductive. XnT and SEM results show that the addition of SEs and carbon improves the structural stability of the anode, with fewer pores and voids. A chemo-elasto-plastic model reveals that SEs and carbon buffer the volume expansion of Si, thus enhancing mechanical stability. The balance between the pros and cons of SEs and carbon in enhancing reaction kinetics and structural stability enables the Si composite anode to demonstrate the highest Si utilization with higher specific capacities and a better rate than pure Si and Si composite anodes with only SEs.

36 MATERIALS SCIENCE↗