Enhanced electrochemical performance of silicon anode materials with titanium hydride treatment

Abstract

As a promising anode material for the next generation of lithium-ion batteries, silicon (Si) suffers from the main problems of severe volume expansion and poor electrical conductivity. Compounding Si-based materials with metal hydrides is one of the ways to overcome these problems. Herein, we proposed TiH2 decorated Si composites prepared by ball milling and subsequent high-temperature calcination to restrain the volume expansion of Si and enhance the electrical conductivity. The resulting Si-0.05TiH2 anode delivered a reversible discharge capacity of 766.1 mAh/g after 100 cycles at a current density of 100 mA/g and better rate capability than the Si anode. Additionally, the impedance measurements and the density functional theory (DFT) calculation demonstrated that the insertion of Ti after dehydrogenation of TiH2 enhanced the conductivity of the composite anode. The charge transfer resistance (Rct) of Si-0.05TiH2 and Si anodes were 43.03 Ω and 609.6 Ω, respectively, indicated that the charge transfer process of Si/TiH2 electrodes was faster. This study provides a new strategy for compounding metal hydrides with Si, and a further attempt to enhance the electrochemical properties of Si.