Turning Trash into Treasure: MXene with Intrinsic LiF Solid Electrolyte Interfaces Performs Better and Better during Battery Cycling

Abstract Commercialization of lithium ion batteries has accelerated dramatically over the last few decades. Single‐layered Ti₃C₂ (s‐Ti₃C₂) is effectively prepared by etching Ti₃AlC₂ via simple treatment with HCl and LiF, producing inevitably sediments always discarded after etching. This study explores the effect of LiF doping of multilayered Ti₃C₂ to form m‐Ti₃C₂/LiF consisting essentially of the sediments. Simple half‐cells assembled with m‐Ti₃C₂/LiF sediments suggest that LiF suppresses electrode volume expansion and surface cracking during cycling promoting Li⁺ intercalation/deintercalation. The data also suggest that LiF promotes formation of stable artificial solid electrolyte interfaces to prevent electrolyte and electrode degradation. The capacity of m‐Ti₃C₂/LiF sediments derived cells maintains 136 mAh g⁻¹ after 1500 cycles at 300 mA g⁻¹ while s‐Ti₃C₂ from supernatants physically mixed with 20 wt% LiF shows a capacity of 335 mAh g⁻¹ (100th cycle) at 100 mA g⁻¹ with an initial coulombic efficiency of 83%. Half‐cell anodes made of Ti₃C₂ etched by HF, commercial TiO₂, and Sn powder mixed physically with 20 wt% LiF exhibit improved performance with cycling. These results indicate that the always discarded sediments can be directly used in LIBs and simple doping with LiF obviously improves the electrochemical performance of materials.