In the rapid development of new energy vehicles, the performance requirements for batteries are getting higher and higher. Silicon-based anode materials have become the key to break through the energy density bottleneck of lithium-ion batteries due to their ultra-high theoretical specific capacity (4200 mAh/g) and abundant reserves. Today we talk about silicon-carbon anode materials.

I. Advantages and challenges of silicon-based anode materials

Advantage: The theoretical specific capacity of silicon-based anode materials is as high as 4200 mAh/g, which is much higher than the 372 mAh/g of the traditional graphite anode. in addition, the abundant natural reserves of silicon and its low price make it one of the most promising anode materials.

Challenges: Despite the many advantages of silicon-based anode materials, they still face some challenges in practical applications. First, silicon undergoes significant volume expansion (>300%) during lithiation, leading to structural collapse of the electrode material. Second, the dynamic rupture and reconfiguration of the solid electrolyte interface (SEI) membrane can cause irreversible loss of active lithium ions and reduce the cycle life of the battery.

II. Research progress of silicon-based negative electrode materials

Material Preparation: Silicon materials are prepared by a variety of methods, including chemical vapor deposition (CVD), physical vapor deposition (PVD) and electrochemical deposition methods. In recent years, researchers have also explored methods to extract silicon from natural minerals and waste materials. For example, high-performance silicon anode materials have been prepared by magnesium thermal reduction using natural materials such as beach gravel and rice husk.

Composite Processes: In order to address the volume expansion of silicon materials, researchers have developed a variety of composite processes. Among them, carbon cladding is a common method that,By coating a layer of carbon material on the silicon surface, the volume expansion of silicon can be effectively suppressed and the conductivity of the electrode can be improved.In addition, composites of silicon with metals or metal oxides, such as silicon-copper composites and silicon-nickel composites, also exhibit good electrochemical properties.

Elemental doping: Elemental doping is another effective method to enhance the performance of silicon-based anode materials. By doping non-metallic elements such as nitrogen and sulfur, the electronic conductivity of silicon materials can be significantly improved. For example, nitrogen-doped silicon materials exhibit higher stability and capacity retention during cycling. Metal element doping, such as nickel and magnesium, can improve the electrical conductivity and structural stability of silicon by modulating its energy band structure.

Nanosized Silicon Materials: Nanosizing can significantly enhance the electrochemical properties of silicon materials. The critical size range of silicon nanomaterials is 20-870 nm, In this context,Silicon nanomaterials can effectively inhibit volume expansion and improve the cycling stability of the battery.However, the high specific surface area of silica nanomaterials can lead to the overgrowth of SEI membranes, and its performance needs to be optimized by rational structural design.

SEI membrane research: the stability of SEI membrane is crucial to the performance of silicon-based anode materials. Through electrolyte additive optimization, surface engineering and core-shell structure design, the composition and structure of SEI membrane can be effectively regulated to improve its mechanical stability and chemical inertness. For example, fluorinated ethylene carbonate (FEC) additives can generate LiF-rich inorganic layers to enhance the stability of SEI membranes.

III. Outlook for industrialization and application

The industrialization process of silicon-based anode materials is at a critical stage where technological breakthroughs and large-scale applications promote each other. Current research mainly focuses on the preparation of carbon skeleton composite silicon-carbon materials with three-dimensional porous structure by chemical vapor deposition. This structural design not only effectively mitigates the volume expansion effect of silicon material in the process of charging and discharging, but also significantly improves the cycling stability and multiplier performance of the material.

Leading companies at home and abroad, such as Betray, have made breakthroughs in the process innovation of silicon-based anode materials. Through the optimization of synthesis process parameters, the development of new reactor equipment and the establishment of a complete quality control system, these companies have achieved large-scale mass production and have a stable batch supply capacity.

The industrialization of silicon-based anode materials needs to focus on breaking through the following key directions: firstly, in terms of material structure design, efforts should be made to develop composites with multilevel pore structure and core-shell cladding function; secondly, in terms of cost control, it is necessary to reduce costs and increase efficiency through the large-scale equipment and the localization of raw materials; thirdly, in terms of supporting technology, it is necessary to strengthen synergic development of key materials, such as new electrolyte system and high-performance conductive agent; fourthly, the application of silicon anode materials in all-solid-state batteries is also the focus of current research. Third, in terms of supporting technology, it is necessary to strengthen the synergistic development of key materials such as new electrolyte systems and high-performance conductive agents; fourth, the application of silicon anode materials in all-solid-state batteries is also the focus of current research.

With its significant advantages, silicon-based anode materials have become the focus of cutting-edge research in the field of high-energy storage. Through continuous technological innovation and process optimization, silicon-based anode materials are expected to play an important role in the field of new energy vehicles and energy storage, and promote the global energy transition.