The Electrolysis of Anti-Perovskite Li₂ OHCl for Prelithiation of High-Energy-Density Batteries

Anti-perovskite type Li₂ OHCl was previously studied as a solid-state Li⁺ conductor. Here, we report that the Li₂ OHCl can be electrolyzed at 3.3 V or 4.0 V, with the creation of O₂ /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 Li₂ OHCl is oxidized at a constant voltage of 3.3 V. In neutral electrolyte, the oxidization of Li₂ 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 Li₂ OHCl. The electrolysis of Li₂ 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 Li₂ 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 O₂ (NMC811) cathode and prelithiated Si@C anode exhibited increased capacities with the increment of prelithiation dosages.