Suspension electrolyte for lithium metal battery regeneration

Background

Lithium metal batteries (LMBs) hold immense promise for next-generation energy storage due to their potential for high energy density, surpassing current lithium-ion batteries. This advancement is crucial for meeting the growing demands of electric vehicles and portable electronics, where longer range and extended usage time are highly desirable. However, realizing the full potential of LMBs faces significant hurdles.

A major challenge lies in the unstable nature of the lithium metal anode during repeated charge and discharge cycles. The formation of lithium dendrites, needle-like structures that grow on the anode surface, leads to rapid capacity fade, short circuits, and safety hazards. Additionally, the continuous reaction between lithium metal and the electrolyte forms an unstable solid-electrolyte interphase (SEI) layer, consuming active lithium and further degrading battery performance.

Existing approaches to address these issues, such as electrolyte additives and artificial SEI layers, have shown limited success in preventing dendrite growth and ensuring long-term stability, particularly at high charge/discharge rates.

Technology overview

Researchers at The University of Texas at Austin invented a novel approach to improve the performance and lifespan of lithium metal batteries (LMBs), by means of a suspension containing magnetically responsive vermiculite (VMT) nanosheets, and a process to regenerate a more uniform electrode. VMT nanosheets incorporated into the electrolyte can be oriented by an external magnetic field during battery operation, facilitating in situ regeneration of the battery. The regeneration process redistributes Li-ion flux and promotes the formation of an inorganic-rich solid-electrolyte interphase (SEI), leading to uniform and compact lithium deposition. While conventional approaches such as coatings of 2D materials lose effectiveness over time due to lithium deposition on their surfaces, this new approach avoids that limitation and provides in situ dynamic regeneration capability.

The success of this approach was first demonstrated in Li||Li symmetric cells, improving lifespan by 5× over the control (350 hours at 2 mA cm⁻² and 2 mA h cm⁻²). In longer tests of full-cells, capacity retention was significantly boosted to 67% (vs. 11% in control cells) after 500 cycles at 1C and 3 mA h cm−2 for Li||LiNi_1/3Mn_1/3Co_1/3O₂ (NMC) full cells. By controlling nanosheet orientation during operation, the technology effectively reshapes lithium deposition, which reduces overpotential, and extends battery lifespan for high-energy LMBs.

Benefits

Improved battery lifespan and capacity retention for lithium metal batteries (LMBs)
Uniform and compact lithium deposition, leading to extended cycling stability
In situ regeneration of the battery by redistributing ion flux and forming an inorganic-rich solid-electrolyte interphase (SEI)
Use of low-cost, readily available, and environmentally friendly vermiculite nanosheets
Compatibility with existing roll-to-roll battery manufacturing processes