Solving the Challenges of Solid-State Battery Recycling

Solid-state batteries have long been touted as the next big thing in energy storage, offering higher energy density, faster charging times, and enhanced safety compared to traditional lithium-ion batteries. However, one of the major roadblocks to their widespread adoption has been the challenge of recycling. 

 

Car batteries awaiting recycling. Image used courtesy of Adobe Stock

 

Why are SSBs so difficult to recycle, and what solution did the researchers develop? Lawrence Berkley National Laboratory researchers recently developed a solid-state battery (SSB) solution to solve this issue. 

 

Solid-State Batteries

Solid-state batteries represent a significant advance over traditional lithium-ion batteries, offering higher energy density, faster charging times, and enhanced safety. Unlike lithium-ion batteries, which use a liquid or gel-like electrolyte to facilitate ion movement between the anode and cathode, SSBs employ a solid electrolyte. This eliminates the risk of electrolyte leakage, a common issue in liquid-based systems that can lead to catastrophic failures like fires or explosions. The solid-state architecture also allows for using lithium metal as the anode, which has a much higher theoretical capacity than the graphite anodes used in lithium-ion batteries.

 

Solid-state batteries have a solid electrolyte. Image used courtesy of Murata
 

From a physics perspective, the solid electrolytes in SSBs offer superior ionic conductivity, enabling faster electron flow and, thus, quicker charging and discharging rates. The absence of liquid components also means SSBs are less sensitive to temperature variations, making them more versatile for various applications, from electric vehicles to portable electronics and grid storage. Moreover, the compact nature of SSBs allows for more flexible form factors, which is crucial for device miniaturization.

 

Recycling Challenges for Solid-State Batteries

Recycling SSBs presents a unique set of challenges compared to liquid-based counterparts. 

One challenge is that the solid electrolyte and electrode materials are often fused, making them difficult to separate for recycling. Traditional methods that involve shredding the battery and using solvents to dissolve the electrolyte are less effective with SSBs due to their solid-state nature. Moreover, the high-quality materials used in SSBs, like lithium metal and advanced ceramics for the solid electrolyte, require specialized recycling processes to recover them in a usable form.

 

A recycling process for SSBs. Image used courtesy of Azhari et al.

 

Another challenge is the energy-intensive nature of recycling processes for SSBs. The tightly bound components require more energy to disassemble, which can offset some environmental benefits of using a more efficient battery. Additionally, the lack of a standardized recycling process for SSBs complicates matters, as different manufacturers may use other materials and designs, requiring customized recycling approaches for each.

 

Solid-State Battery Research and Solutions

In a recent research from Lawrence Berkeley National Laboratory, a group of scientists explored developing and characterizing a novel electrolyte for solid-state batteries, termed ORION (organo-ionic) conductors. 

These conductors are engineered using supramolecular chemistry, featuring a unique coordination chemistry that allows for structural and mobile lithium ions. The electrolyte is viscoelastic, meaning it possesses both solid-like and fluid-like characteristics. Specifically, the material is solid at battery operating temperatures (-40°C to 45°C) and is liquid above 100°C.  This enables both the fabrication of high-quality SSBs and the recycling of their cathodes at the end of life.

 

The ORION-based SSB. Image used courtesy of Bae et al.
 

To characterize the properties of the ORION conductors, the researchers employed analytic techniques like X-ray diffraction and impedance spectroscopy. They found the electrolyte exhibits high ionic conductivity, making it suitable for high-performance SSBs. The paper also discusses the thermal properties of the electrolyte, emphasizing its stability and suitability for various operating conditions.

One of the most groundbreaking aspects of this research is the recyclability of the ORION conductors. The authors demonstrate that the electrolyte can be melted and separated from the other battery components, facilitating easy recycling.