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.Etching Ti3AlC2 using HCl and LiF results in the supernatants containing single‐layered Ti3C2 and multilayered Ti3C2/LiF sediments [m‐Ti3C2/LiF(S1)] always discarded as “debris”, further to be investigated in lithium ion batteries. The m‐Ti3C2/LiF(S1) shows negative capacity fading with capacity increasing to 198 mAh g−1 after 600 cycles at 30 mA g−1. LiF takes a significant role in electrochemical performance enhancing.