The Electrolysis of Anti‐Perovskite Li 2 OHCl for Prelithiation of High‐Energy‐Density Batteries

Anti‐perovskite type Li 2 OHCl was previously studied as a solid‐state Li + conductor. Here, we report that the Li 2 OHCl can be electrolyzed at 3.3 V or 4.0 V, with the creation of O 2 /HCl gases and the release of 2 equiv. Li + via two different decomposition routes, depending on the acidity of electrolyte. In the electrolyte with trace acid, the Li 2 OHCl is oxidized at a constant voltage of 3.3 V. In neutral electrolyte, the oxidization of Li 2 OHCl 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 Li 2 OHCl. The electrolysis of Li 2 OHCl delivers a lithium releasing capacity as high as 810 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 Li 2 OHCl as the lithium source, silicon‐carbon (Si@C) composite anode can be effectively prelithiated. The full cells composed of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode and prelithiated Si@C anode exhibited increased capacities with the increment of prelithiation dosages.