Studies on preventing Li dendrite formation in Li-S batteries by using pre-lithiated Si microwire anodes

In this work, detailed studies on Li dendrite formation in Li-S Batteries are reported. Li dendrites can grow rapidly, may pierce through or can easily grow around the separator. Dendrites can even lead to short circuits when cathode and/or anode are wrapped with the separator. By replacing the Li metal anode with a pre-lithiated Si anode, these dendrite problems could be successfully prevented and were not observed for more than 200 cycles. The here used Si microwire array anodes are examined with ether and carbonate based electrolytes and different charging conditions vs. a Li metal counter electrode and demonstrate very high capacities matching the theoretical values. Electrochemical pre-lithiated Si microwire array anodes are examined in full cells with binder free, sulfur infiltrated carbon nanotube cathodes (CNT-S) and various polysulfide or Li2S containing electrolytes. The average polysulfide chain length and the presence of LiNO3 in the electrolyte have a great impact on the cycle stability of the cell, next to the charging conditions.