Li2O-Based Cathode Additives Enabling Prelithiation of Si Anodes

Low first-cycle Coulombic efficiency is especially poor for silicon (Si)-based anodes due to the high surface area of the Si-active material and extensive electrolyte decomposition during the initial cycles forming the solid electrolyte interphase (SEI). Therefore, developing successful prelithiation methods will greatly benefit the development of lithium-ion batteries (LiBs) utilizing Si anodes. In pursuit of this goal, in this study, lithium oxide (Li₂ O) was added to a LiNi_0.6 Mn_0.2 Co_0.2 O₂ (NMC622) cathode using a scalable ball-milling approach to compensate for the initial Li loss at the anode. Different milling conditions were tested to evaluate the impact of particle morphology on the additive performance. In addition, Co₃ O₄, a well-known oxygen evolution reaction catalyst, was introduced to facilitate the activation of Li₂ O. The Li₂ O + Co₃ O₄ additives successfully delivered an additional capacity of 1116 mAh/g_Li2O when charged up to 4.3 V in half cells and 1035 mAh/g_Li2O when charged up to 4.1 V in full cells using Si anodes.