# Engineering thin 3D Li-composite foil negative electrodes with high mechanical toughness

## TL;DR

Researchers created a durable, thin lithium composite electrode that improves battery performance and longevity.

## Contribution

A novel 3D Li-composite foil combining Li-Zn alloy and Li3N-enriched CNT network for high mechanical toughness and electrochemical performance.

## Key findings

- The composite electrode achieves a rupture toughness of 1.3 × 10⁶ J/m³, a 12-fold improvement over bare lithium.
- The electrode enables extended cyclability (>500 cycles) and high-rate operation (10 C) in lithium metal batteries.
- An 8.5 Ah pouch cell demonstrates a practical specific energy of 553 Wh kg−1 at cell level.

## Abstract

Current three-dimensional lithium negative electrodes are plagued by inherent trade-offs among mechanical robustness, thin processability, and electrochemical performance. Here, we engineer a free-standing Li-composite foil negative electrodes by integrating a lithiophilic Li-Zn alloy with a Li3N-enriched carbon nanotube network. The Li-Zn alloy strengthens tensile resistance and regulates lithium deposition, while the Li3N-enriched carbon nanotube network reinforces mechanical toughness, achieving a rupture toughness of 1.3 × 10⁶ J/m³, a 12-fold enhancement over bare lithium. This property enables the fabrication of thin negative electrodes (<10 μm) that resist pulverization during deep Li plating/stripping. In cells with LiNi0.8Co0.1Mn0.1O2 positive electrodes, the composite negative electrode facilitates extended cyclability (>500 cycles in coin cells at 1 C, 92% retention after 300 cycles in Ah-grade pouch cells at 0.5 C) and sustain high-rate operation (10 C). An 8.5 Ah pouch cell demonstrates a practical specific energy of 553 Wh kg−1 at cell level when tested at 0.1 C. This work presents a design strategy for realizing high-energy, long-cycle-life lithium metal batteries.

Lithium metal offers high specific capacity but suffers from dendrite growth and poor cycling stability. Here, authors develop a 3D Li-Zn-Li3N/CNT composite combining ductile Li-Zn alloy and a mechanically robust Li3N-CNTs network, enabling thin, durable electrodes with uniform lithium deposition, demonstrating a pouch-cell with a specific energy of 553 Wh kg-1.