Rational Design of 2D Sn/MXene Hybrid As Anode Battery with Long Cycling and High Rate Performance

Abstract

Current lithium ion batteries (LIBs) can’t provide sufficient energy density due to a limiting capacity of 372 mAh/g from graphite anode and a low capacity from cathode. Therefore, searching novel electrode materials for large energy storage that can deliver much higher energy density becomes critical. Li-M (M = Si, Al, Sn) alloy batteries are in particular attracting more attention due to the conspicuous advantages on industrial availability, specific capacity and rate capability. Sn has a 3 times greater capacity of ~1000 mAh/g that allows it as one of primary candidates for the next-generation LIBs. Scientists have made numerous attempts to stabilize the Sn alloy geometry by constructing various structures. However, most of these nano-structured particles can’t long survive because of the severe agglomeration and pulverization, nevertheless some types of carbon may limit the particle growth. Here we report a rational design of 2D Sn/MXene hybrid as anode battery with long cycling (over 1000 cycles) and high rate performance (over 5C), which is based on our previous work on Sn (Kang et al Nano Letter 2018; Liu et al Nano Letter 2016; Liu et al Chem Commun 2017) and MXene (Nagui et al Adv Mater 2011). The excellent Li+/e- conductivity and strong chemical/physical bonding of the interface between MXene and Sn lead to the improved half-cell (VS Li) and full-cell (VS NMC) battery performance at both coin and pouch cell scales. The structure evolution of the hybrid composite, the SEI forming and disappearing, and the interface between electrode and electrolyte upon cycling will be investigated via electrochemical measurements and in-situ TEM technique. Our strategy based on the benefits of MXene and the major capacity contribution of loaded metal active material can elevate the development and utilization of this new type of 2D hybrid materials with a high rate capability, high storage capacity, and low voltage, making it a promising candidate for next-generation batteries.