Li 2 O:Li–Mn–O Disordered Rock‐Salt Nanocomposites as Cathode Prelithiation Additives for High‐Energy Density Li‐Ion Batteries

The irreversible loss of lithium from the cathode material during the first cycles of rechargeable Li‐ion batteries notably reduces the overall cell capacity. Here, a new family of sacrificial cathode additives based on Li 2 O:Li 2/3 Mn 1/3 O 5/6 composites synthesized by mechanochemical alloying is reported. These nanocomposites display record (but irreversible) capacities within the Li–Mn–O systems studied, of up to 1157 mAh g −1 , which represents an increase of over 300% of the originally reported capacity in Li 2/3 Mn 1/3 O 5/6 disordered rock salts. Such a high irreversible capacity is achieved by the reaction between Li 2 O and Li 2/3 Mn 1/3 O 5/6 during the first charge, where electrochemically active Li 2 O acts as a Li + donor. A 13% increase of the LiFePO 4 and LiCoO 2 first charge gravimetric capacities is demonstrated by the addition of only 2 wt% of the nanosized composite in the cathode mixture. This result shows the great potential of these newly discovered sacrificial additives to counteract initial losses of Li + ions and improve battery performance.