High-Performance Dual-Ion Battery Based on Silicon-Graphene Composite Anode and Expanded Graphite Cathode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Dual-ion batteries (DIBs) offer high voltage, low cost, and safety, utilizing simultaneous anion and cation intercalation.
• Graphite cathodes are common due to their ability to intercalate anions at high voltages (up to 5.2 V vs. Li+/Li).
• Silicon anodes possess high theoretical capacity (4200 mAh g-1) but suffer from volume expansion and poor conductivity, limiting their use in DIBs.

Purpose of the Study:

• To develop a stable and high-capacity anode for dual-ion batteries (DIBs).
• To address the challenges of volume expansion and low conductivity in silicon anodes for DIB applications.
• To enhance the energy density of DIBs by combining advanced anode materials with established cathode materials.

Main Methods:

• Fabrication of a strongly coupled silicon and graphene composite (Si@G) anode using in-situ electrostatic self-assembly and post-annealing reduction.
• Investigation of the Si@G anode's performance in half-cell configurations against bare Si anodes.
• Assembly and testing of full DIBs using the Si@G anode and expanded graphite (EG) cathode.

Main Results:

• The Si@G anode demonstrated superior capacity retention, maintaining 1182.4 mAh g-1 after 100 cycles, compared to 435.8 mAh g-1 for the bare Si anode.
• Full Si@G//EG DIBs achieved a high energy density of 367.84 Wh kg-1 at a power density of 855.43 W kg-1.
• Improved electrochemical performance is attributed to controlled volume expansion, enhanced conductivity, and matched kinetics between anode and cathode.

Conclusions:

• The developed Si@G composite anode effectively mitigates silicon's drawbacks, enabling high-performance DIBs.
• This work presents a promising strategy for creating high energy density dual-ion batteries.
• The Si@G//EG system shows significant potential for next-generation energy storage solutions.