Lithium-ion batteries (LIBs) have been widely used as a new energy storage system with high energy density and long cycle life. However, the solid electrolyte interfacial (SEI) layer formed on the surface of anode consumes excess active lithium during the initial cycle, resulting in an initial irreversible capacity loss (ICL) and reducing the overall electrochemical performance. To solve the critical issue, pre-lithiation technology has been accepted as one of the most promising strategies. Due to the pre-lithiated treatment provides additional active lithium to compensate for the ICL and effectively improves initial Coulombic efficiency (ICE), leading to raising the working voltage, increasing the Li⁺ concentration, as well as improving the energy density and cycle stability of LIBs. In this overview, the causes of ICL in LIBs are analyzed from different perspectives, and various pre-lithiation strategies are systematically classified and summarized. Finally, some current problems and development prospects in this field are summarized, with prospects for realizing industrialized technologies.
Graphite (Gr) is a low cost, high energy density anode material for lithium-ion batteries (LIBs). However, Gr has an obvious drawback of low initial Coulombic efficiency (ICE). To address this issue, this paper proposes a straightforward and effective pre-lithiation method for pre-lithiating Gr anodes. This is achieved primarily by selecting the potential difference between the 2-methyltetrahydrofuran solution of phenanthrene-lithium (Ph-Li-2-Me-THF), which has a low redox potential, and Gr to spontaneously drive the reaction. Ph-Li-2-Me-THF has a low redox potential of 0.1 V, allowing for quick pre-lithiation without co-embedding of the solvent by controlling immersion time. The pre-lithiated Gr (pGr) surface was pre-formed with a solid electrolyte interface (SEI) layer, which reacted on contact with the electrolyte to increase the stability and densification of the SEI layer, which consisted of homogeneous Li₂CO₃, ROCO₂Li and LiF, resulting in high ICE, rate capability and cycling performance. Thanks to these advantages, full cells assembled with commercial LiFePO₄ (LFP) and NCM811 cathodes have significantly improved ICE, cycling performance and energy density, showing promising and valuable applications.

 

Lithium-ion batteries; irreversible capacity loss; active lithium loss; solid electrolyte interfacial layer; initial coulombic efficiency