In our computations, we treat the Li + and e -pair as a single lithium atom. The initial structures are prepared by adding the Li atom along the S chain at distinct positions. These structures then go through atomic coordinate optimizations. In total, about 360 initial structures and optimizations have been carried out. At each lithiation state, the lowest-energy product structure is considered as a candidate for the actual lithiation product. As indicated in Eq. ( ), we continue with sequential lithiation reactions until the saturation of the sulfur chain with lithium atoms is achieved. For simplicity, we specifically consider even numbers of lithium atoms in each reaction.