A recent study conducted at Helmholtz-Zentrum Berlin (HZB) has found that solid-state lithium-sulfur batteries have the potential to provide greater energy densities and improved safety compared to conventional lithium-ion batteries.

However, the results of this study have revealed a significant bottleneck in the development of solid-state batteries. The findings indicate that slow ionic transport in the cathode composites is a major limitation.

Lithium-ion batteries have slow charging and discharging mechanism caused by slow lithium-ion transport within a composite cathode.

The challenge now is to find ways to improve the ion delivery rate within the cathode composite.

The researchers emphasized that without the direct visualization of the reaction front within the cathode composite, this effect would have remained unnoticed despite its importance for the development of solid-state batteries.

Method of Study

To observe the movement of lithium-ions between the anode and cathode in a solid-state lithium-sulfur battery, the researchers designed a specialized cell.

However, detecting lithium using X-ray methods proved challenging.

To overcome this, physicists Robert Bradbury and Ingo Manke used neutron radiography and neutron tomography methods.

These methods are highly sensitive to lithium, allowing for the examination of the sample cell. The research involved collaboration between various groups, from Giessen (JLU), Braunschweig (TUBS), and Jülich (FZJ).

According to Bradbury, the use of neutron radiography allowed for the direct observation of lithium ions, leading to a better understanding of the limitations of the battery’s performance.

The operando neutron radiography data revealed that the composite cathode had a reaction front of lithium ions propagating through it, confirming that a low effective ionic conductivity had a negative impact on battery performance.

The 3D neutron tomography images also showed trapped lithium concentrated near the current collector during recharging, which reduced the battery’s capacity as not all the lithium was transported back when charged.

The researchers noted that the observed distribution of lithium in the battery was highly consistent with a model based on the theory of porous electrodes.

They explained that the electronic and ionic conductivity conditions from the model matched well with the data obtained from neutron imaging, indicating the accuracy of the model.

In March 2023, researchers at HZB found that solar cells made of metal halide perovskites achieve high efficiencies and can be produced from liquid inks with little energy input.

Researchers at Swansea University in Wales, United Kingdom, recently established a low-cost and scalable carbon ink formulation capable of unlocking the potential for manufacturing perovskite solar cells at scale.