Marja Vilkman (middle, left) and her research team in the labs at VTT, Finland.

A self-healing battery is a new star on the battery research sky. The idea is to slow down the aging process in the battery substantially. This is being done by hindering dendrite growth at the anode of the battery and has the potential to increase the lifetime and energy density of Li-metal batteries by 50 percent compared to today’s Li-ion batteries. This is what Hidden, one of the research projects within Battery 2030+, aims for.

Today’s most common electric vehicle (EV) batteries use graphite as the anode material. The main problem in the graphite anode is its limited energy density, which also eventually hinders the driving range of EV’s. The ideal anode material option for enabling high energy density batteries is metallic lithium. Unfortunately, the formation of dendrite growth, a form of “plaque” at the electrode surface, is an essential factor that limits the use of metallic lithium as the anode. Solid-State electrolytes (SSEs) could help controlling the nucleation and prevent the growth of dendrites, but it has proven to be difficult to develop and process SSEs combining high enough conductivity, mechanical properties, and stabilized, electrochemically active interphases with electrode.

To get hold of the dendrite nucleation and growth, one needs to know more fundamentally what is happening in the battery and find solutions to prevent unwanted reactions at cell level. To do this, several things need to be in place; one is to use non-invasive analyzing tools to detect dendrites and applying multiscale modelling to accelerate the discovery of next generation electrolytes for alkali-metal anode-based batteries.

  • We aim to develop just that, and in combination with advanced algorithms, we can monitor the dendrites in the lab, model the growth virtually, and trigger the self-healing when needed, says Dr. Marja Vilkman, project leader for Hidden. We are looking at chemistry-neutral thermotropic ionic liquid crystals (TILCs)-based self-healing electrolytes. Their structure will be simultaneously i) encoded according to their tailor-made molecular design and ii) changed with the temperature; thus breaking the formed dendrites mechanically during phase transitions and upon heating above their clearing point. This dynamic process is fully reversible with the temperature. When complemented by a polarized piezoelectric polymeric separator, that creates an electric field when bended, the dendrite formation will diminish. If TILCs are topped up with protective additives to generate self-healing electrolytes, dendrite nucleation and growth will be ultimately put under smart control to make batteries with enhanced energy density and improved lifetime.

Another important part of the Hidden project is to make sure that the materials and their processes are scalable and industrially fit for manufacturing. Europe has set forth to be the first carbon free continent by 2050. Hidden contributes by enabling sustainable energy storage with longer battery lifetime and higher energy storage capacity.

Short fact
The Hidden project aims to:

  • develop novel self-healing thermotropic liquid crystalline electrolytes and piezoelectric separator technologies
  • investigate both technologies with protective additives
  • apply multiscale modelling means for electrolyte design and analysis algorithm to monitor the dendrite nucleation and growth