Increasing Li-ion conductivity in argyrodite solid electrolytes

argyrodites_tocThe use of liquid electrolytes makes current batteries prone to dangerous thermal runaway reactions, igniting the battery, as seen recently in the Samsung Note 7 phones. To make batteries safer the liquid electrolyte can be replaced by a solid electrolyte, which is not flammable. However, before solid electrolytes can be used the Li-ion conductivity must be equally good as in liquid electrolytes.

Currently several solid electrolytes are known with Li-ion conductivities comparable to that in liquid electrolytes, one of which are lithium argyrodites. To gain a better understanding of Li-diffusion in lithium argyrodites density functional theory molecular dynamics simulations have been performed.The simulations showed that the position of halogen atoms in the crystals has a large impact on the Li-ion conductivity, and that altering the halogen positions in lithium argyrodites during synthesis could increase the Li-ion conductivity of these materials.

The simulation results show that the Li-ion conductivity in these materials can a factor of 2 larger than the currently highest value. (Article)