The electrolysis of anti-perovskite Li2OHCl for prelithiation of high energy density batteries.

Anti-perovskite type Li2OHCl was previously studied as a solid-state Li+ conductor. Here, we report that the Li2OHCl can be electrolyzed at 3.3 V or 4.0 V, with the creation of O2/HCl gases and the release of 2 eq. Li+ via two different decomposition routes, depending on the acidity of electrolyte. In the electrolyte with trace acid, the  Li2OHCl is oxidized at a constant voltage of 3.3 V. In neutral electrolyte, the oxidization of  Li2OHCl starts at 4.0 V, but the produced HCl will increase the acidity of electrolyte and lead to a voltage drop to 3.3 V for the electrolysis of  Li2OHCl . The electrolysis of  Li2OHCl delivers a lithium releasing capacity as high as 812 mAh g-1 , with an equivalent Li-deposition or Li-intercalation on anode, making it a promising candidate as a Li reservoir for prelithiation of anode. Using  Li2OHCl as the lithium source, silicon-carbon (Si@C) composite anode can be effectively prelithiated. The full cells composed of LiNi0.8Mn0.1Co0.1O2(NMC811) cathode and prelithiated Si@C anode exhibited increased capacities with the increment of prelithiation dosages.