Single-Layer Graphene Oxide: A New Dawn in the Field of Lithium-Ion Batteries

Introduction

Against the backdrop of the rapid development of the new energy industry, lithium-ion batteries (LIBs), as core energy storage devices, are widely used in electric vehicles, portable electronic equipment, and other fields. However, current LIBs face challenges such as insufficient energy density, short cycle life, and the need for improved safety, thus urgent requiring new materials to break through performance bottlenecks. Single-layer Graphene Oxide (SLGO), with its unique structure and excellent properties, has emerged as a key material to address the performance issues of LIBs, injecting new vitality into their development.

1. Unique Structure and Properties of Single-Layer Graphene Oxide

SLGO possesses a two-dimensional planar structure with a single atomic layer thickness. Carbon atoms form a hexagonal ring framework through sp² hybridization, and the surface is rich in oxygen-containing functional groups such as hydroxyl and epoxy groups. This structure endows SLGO with multiple excellent properties: in terms of electrical performance, high conductivity can be achieved through reduction regulation, which is conducive to charge transfer; mechanically, its tensile strength reaches 130 GPa, which can enhance the structural stability of electrodes; thermally, its thermal conductivity is approximately 5000 W/(m·K), which can effectively alleviate battery heating issues. These properties are highly compatible with the requirements of LIBs for electrode materials and electrolyte modification materials, laying a foundation for improving the comprehensive performance of batteries.

2. Application Exploration of Single-Layer Graphene Oxide in Lithium-Ion Battery Cathode Materials

Traditional LIB cathode materials, such as lithium iron phosphate (LFP), have limitations of low electrical conductivity (10⁻⁹~10⁻¹⁰ S/cm) and poor lithium-ion mobility, which restrict the rate performance of batteries. Compositing SLGO with cathode materials has become an important solution: when adopting a semi-encapsulated structure, SLGO forms a conductive network on the surface of LFP particles, increasing the electrode conductivity by 2-3 orders of magnitude; although a fully encapsulated structure can further enhance stability, oxygen-containing functional groups may hinder lithium-ion transport, leading to a decrease in ion mobility by approximately 10%. It is speculated that this is caused by weak interactions between functional groups and lithium ions, and subsequent optimization of the structure through precise regulation of surface groups is required.

3. Application Progress of Single-Layer Graphene Oxide in Lithium-Ion Battery Anode Materials

3.1 Challenges and Breakthroughs in Direct Use as Anode Materials

When SLGO is directly used as an anode, its two-dimensional sheets tend to stack, resulting in reduced specific surface area and poor rate performance. This issue can be improved through different preparation methods: the initial cycle specific capacity of SLGO anodes prepared by mechanical exfoliation is approximately 600 mAh/g, but the capacity retention rate is only 65% after 50 cycles; in contrast, SLGO prepared by the thermal expansion method forms a porous structure, with the initial specific capacity increased to 1200 mAh/g and the capacity retention rate still reaching 88% after 100 cycles, significantly improving cycle stability.

3.2 Research and Innovation in Composite Anode Materials

The composite of SLGO with transition metal oxides and silicon-based materials can synergistically improve anode performance. For example, in the Si/(G+C) composite material, SLGO acts as a buffer layer and conductive framework, effectively alleviating the 300% volume expansion of silicon materials during charge-discharge cycles. This increases the electrode capacity retention rate from 20% (pure silicon) to 75% after 50 cycles. However, the preparation process of this composite material requires the use of high-cost catalysts, leading to high production costs, and there are safety hazards caused by interface reactions, so further optimization of the preparation process is still needed.

4. Other Applications of Single-Layer Graphene Oxide in Lithium-Ion Batteries

4.1 Advantages as a Conductive Additive

As a conductive additive, SLGO can construct a three-dimensional conductive network, reducing the amount of additives while improving conductivity. Comparative experiments show that adding 5% SLGO to silicon-based anodes increases the conductivity by 40% compared to adding 10% natural graphite, improves the battery energy density by 15%, and extends the cycle life by 2 times. This is because the high conductivity and dispersibility of SLGO effectively reduce electrode internal resistance and minimize the invalid consumption of active materials.

4.2 Key Role in Inhibiting Lithium Dendrite Growth

The growth of lithium dendrites can pierce the separator and cause short circuits, posing a serious threat to battery safety. The SLGO coating can inhibit the formation of lithium dendrites through electrostatic repulsion and steric hindrance effects. Studies have shown that after coating the surface of lithium metal anodes with SLGO, the battery shows no obvious signs of lithium dendrites even after 500 charge-discharge cycles, and the Coulombic efficiency remains stable above 99%, significantly improving the safety and cycle stability of LIBs.

5. Preparation Processes and Future Prospects

5.1 Current Status and Challenges of Preparation Processes

Current SLGO preparation methods have their own limitations: mechanical exfoliation can produce high-quality SLGO, but the yield is extremely low, making large-scale production difficult; chemical vapor deposition (CVD) can achieve large-area preparation, but it requires high equipment costs and complex processes; chemical reduction of graphite oxide has high yield, but the product is prone to agglomeration and has uneven performance; the thermal expansion method is simple to operate, but it is difficult to accurately control the sheet thickness and surface functional group content. These issues restrict the large-scale application of SLGO in LIBs.

5.2 Opportunities and Directions for Future Development

Future breakthroughs need to be made in three aspects: first, developing low-cost and large-scale preparation technologies, such as optimizing chemical reduction processes to reduce catalyst costs; second, conducting in-depth research on the interface interaction mechanism between SLGO and various battery components, and regulating its structure through molecular design to further improve battery performance; third, expanding the application of SLGO in new-type batteries such as solid-state lithium batteries and flexible lithium batteries to promote the upgrading of the new energy industry.