Multi-metal anode: Towards safe and energy dense batteries

Introduction

Li metal is considered to be the holy grail anode material due to its high specific capacity and low standard redox potential. It could, in theory, lead to the assembly of extremely high energy density cells. Metal anode-based batteries, in general, represent the main viable option towards a leapfrog in terms of energy density when compared with current Li-ion technology, thus motivating important research efforts in Li-air, Li-Sulfur, and, more recently, solid-state batteries (SSB).

Challenges in Current Technologies

Unfortunately, all of these technologies (even SSB) suffer from dendritic Li growth, which eventually results in short circuit/thermal runaway. Requirements for smooth Li metal electrodeposition mostly consist of fine control of the cation mass transport through the solid electrolyte interphase (SEI). This control is governed by the composition, morphology, and stability of the SEI.

Despite several decades of investigation, it is virtually impossible to achieve the perfect interphase/interface that can sustain thousands of cycles under real battery operation conditions.

Objectives of MULTIMETALBAT

The main objective of MULTIMETALBAT is to bring a new paradigm for metal anodes by developing electrolytes containing a mixture of multiple cations (Li+, Na+, K+, Ca2+, or Mg2+). This approach will modify the overall thermodynamics of plating and stripping when compared with conventional single metal anodes.

Key Features

1. Kinetic competition between various electrodeposition processes will be promoted.
2. The SEI will be engineered to sustain high mechanical, chemical, and thermal stability.
3. This engineering will help promote homogeneous cation diffusion through the SEI.

Targeted Figures of Merit

• Critical current density for 3D metal growth above 10 mA.cm-2.
• 350 Wh/kg energy density for 100 mAh pouch cells, almost doubling that of current Li-ion batteries.

Safety Considerations

Yet, the main objective of MULTIMETALBAT will be increased safety. Extensive standard safety measurements will be performed on prototype cells and compared with Li-ion batteries.