High performance silicon electrode enabled by titanicone coating

Zahilia Cabán Huertas,Cristina Flox,Tanja Kallio,Daniel Settipani,Jordi Jacas Biendicho,Joan Ramon Morante

doi:10.1038/s41598-021-04105-x

Abstract

This paper presents the electrochemical performance and characterization of nano Si electrodes coated with titanicone (TiGL) as an anode for Li ion batteries (LIBs). Atomic layer deposition (ALD) of the metal combined with the molecular layer deposition (MLD) of the organic precursor is used to prepare coated electrodes at different temperatures with improved performance compared to the uncoated Si electrode. Coated electrodes prepared at 150 °C deliver the highest capacity and best current response of 1800 mAh g−1 at 0.1 C and 150 mAh g−1 at 20 C. This represented a substantial improvement compared to the Si baseline which delivers a capacity of 1100 mAh g−1 at 0.1 C but fails to deliver capacity at 20 C. Moreover, the optimized coated electrode shows an outstanding capacity of 1200 mAh g−1 at 1 C for 350 cycles with a capacity retention of 93%. The improved discharge capacity, electrode efficiencies, rate capability and electrochemical stability for the Si-based electrode presented in this manuscript are directly correlated to the optimized TiGL coating layer deposited by the ALD/MLD processes, which enhances lithium kinetics and electronic conductivity as demonstrated by equivalent circuit analysis of low frequency impedance data and conductivity measurements. The coating strategy also stabilizes SEI film formation with better Coulombic efficiencies (CE) and improves long cycling stability by reducing capacity lost.

Highlights

This paper presents the electrochemical performance and characterization of nano Si electrodes coated with titanicone (TiGL) as an anode for Li ion batteries (LIBs)
The use of nanoparticles with a critical particle diameter below 150 nm to reduce particle cracking upon first lithiation[9], formulation of new and effective binder compositions to better compensate for the volume expansion of the silicon[10], synthesis of silicon nanostructures e.g. core–shell11, nanowires[12] or n anotubes[13], with improved performance compared to micro-scale powders, and fabrication of composite materials with carbon to account for the volumetric changes while preserving electrical contact[14]
By combining these two techniques, the substrate is exposed to metal and organic precursors that go through a self-limiting reaction resulting in the deposition of a hybrid inorganic–organic film known as metalocone

Summary

Introduction

This paper presents the electrochemical performance and characterization of nano Si electrodes coated with titanicone (TiGL) as an anode for Li ion batteries (LIBs). A more practical and rational way to mitigate the aforementioned issues that have impeded a performant Si electrode is based on surface modifications by using ALD combined with the more powerful MLD By combining these two techniques, the substrate is exposed to metal and organic precursors that go through a self-limiting reaction resulting in the deposition of a hybrid inorganic–organic film known as metalocone. Recent studies conducted by Abdulagatov et al demonstrate that combining TiCl4-glycerol (GL) results in a film with improved mechanical properties compared to TiCl4-ethylene glycol (EG)[16,17] This approach can be used to produce flexible coatings to control the chemical reactivity and volume expansion of silicon; an example is alucone coating which provides significant improvements in cycling stability, rate capability, and CE for nano-Si composite e lectrodes[18] up to 2000 mAh g −1 at 0.05 C. Other interesting example is the use of zincone which improves discharge capacity to 1741 mAh g −1 at 2000 m Ag−1 and that is related to the formation of a stable LiF-rich SEI layer for the coated s ample[19]

Methods

Results

Conclusion