Architected continuum mixed ionic and electronic conducting alloy negative electrode for fast-charging...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state lithium batteries (ASSLBs) for electric vehicles (EVs) need high specific power.
• Thick negative electrodes in ASSLBs face challenges like fragile conducting networks and dendrite growth, limiting performance.
• Volume changes during alloying and high current densities exacerbate these issues.

Purpose of the Study:

• To develop a novel ternary alloy negative electrode for ASSLBs that overcomes limitations in thick electrodes.
• To enhance mechanical robustness and electrochemical stability for high-power EV applications.
• To enable fast charging and long cycle life in ASSLBs.

Main Methods:

• Fabrication and characterization of an In_0.38Sn_0.33Bi_0.29 ternary alloy negative electrode.
• Electrochemical testing of the alloy electrode, including capacity, critical current density, and cycling performance.
• Assembly and evaluation of In_0.38Sn_0.33Bi_0.29||LiCoO₂ full cells with industry-level mass loading.
• Validation using large-format pouch cells for fast-charging assessment.

Main Results:

• The In_0.38Sn_0.33Bi_0.29 electrode demonstrates a mixed ionic-electronic conducting continuum, stabilizing networks during Li-alloying.
• Stepwise phase formation provides mechanical robustness, relieving stress and minimizing crack propagation.
• Achieved high capacity (~724 mAh g^-1) and critical current density (150 mA cm^-2 at 5.0 mAh cm^-2).
• Full cells retained 87.5% capacity over 1300 cycles at 4.0 C, with high energy densities (203.1 Wh kg^-1 and 670.6 Wh L^-1 at 5.0 C).
• Fast-charging capabilities confirmed in large-format pouch cells.

Conclusions:

• The In_0.38Sn_0.33Bi_0.29 ternary alloy electrode effectively addresses mechanical instability and dendrite growth in ASSLBs.
• The developed electrode design enables high specific power, fast charging, and stable cycling, suitable for EV applications.
• The design principles are transferable to other negative electrode materials for advanced solid-state battery development.