New Breakthrough in Huawei's Silicon-based Anode Materials!

On November 15th, the National Intellectual Property Administration disclosed that Huawei has published a patent for silicon-based anode materials, titled "Silicon-based Anode Material and Its Preparation Method, Battery, and Terminal." The patent involves dispersing high silicon-oxygen ratio particles in a silicon-based matrix with a low silicon-oxygen ratio and coating the surface of the high silicon-oxygen ratio particles with a conductive layer/ion-conductive layer to suppress expansion. This results in an anode material with a capacity of 500 mAh/g, which maintains up to 86% (a decrease of 15 percentage points) of its capacity after 600 cycles and has a charging expansion rate of 20.7% (a decrease of 15 percentage points). The patent primarily addresses the issue of low battery cycle performance due to excessive expansion effects in silicon-based materials, enhancing the cycle stability of the anode.

In addition, on October 29th, another silicon-based anode patent from Huawei was announced (applied for in April 2023), titled "A Silicon-Carbon Composite Material, Its Preparation Method, Negative Electrode Plate, and Lithium-Ion Battery." The patent uses a chemical vapor deposition (CVD) method to adsorb amorphous silicon onto a porous carbon framework, achieving a pure silicon-carbon composite with a specific capacity of up to 1,987 mAh/g, a first-cycle efficiency of 90%, and a swelling rate of 84% after 20 cycles. These two patents adopt silicon-oxygen and silicon-carbon anode routes, respectively, both requiring electronic conductive agents and carbon-coated materials to improve rate performance and maintain interface stability. Currently, the market for silicon-based anode materials is developing concurrently along silicon-oxygen and silicon-carbon paths, with silicon-oxygen anodes having a higher market share. In the long term, CVD method silicon-carbon anodes may become the mainstream direction due to their outstanding performance and greater potential for cost reduction.

Solid-state batteries have the potential to expand the application space for silicon-based anodes. Recently, solid-state batteries have been a hot topic in the market, with capital markets focusing on solid-state batteries and their upstream raw materials. The anode material segment is one of the key links, and lithium metal is considered the ideal negative electrode material for solid-state batteries due to its high theoretical specific capacity and the lowest reduction potential, thus offering significant potential. However, issues such as lithium dendrite growth and volume expansion during cycling need to be addressed to optimize the safety of metallic lithium. Semi-solid-state batteries contain electrolyte and cannot use metallic lithium as the negative electrode, while the full realization of all-solid-state batteries still requires considerable time. Therefore, silicon-based anodes remain an important choice for solid-state batteries in the medium to short term.

The reversible specific capacity of graphite anode materials is approaching its theoretical value of 372 mAh/g, whereas the theoretical specific capacity of silicon-based anodes is ten times that of graphite. The industry currently predominantly adopts a mixed-use solution of silicon-based and traditional graphite, which enhances the energy density of batteries, making it more suitable for high-energy-density solid-state batteries. The cost-effectiveness of CVD method silicon-carbon anodes becomes more prominent after cost reduction. Huawei's previously published patent, "A Silicon-Carbon Composite Material, Its Preparation Method, Negative Electrode Plate, and Lithium-Ion Battery," employs the CVD method silicon-carbon anode route, demonstrating excellent performance in multiple dimensions such as specific capacity, first-cycle efficiency, cycle life, and rate capability. The swelling problem has been significantly improved compared to traditional ball milling methods, leading it to be regarded as the most promising development direction for future silicon-based anodes.

However, the high cost of CVD method silicon-carbon anodes has deterred many downstream manufacturers. For example, when the price of silane gas is 250,000 yuan per ton and the price of porous carbon is 180,000 yuan per ton, the overall cost exceeds 400,000 yuan per ton, with a selling price of over 750,000 yuan per ton. If the prices of silane gas and porous carbon can stabilize below 100,000 yuan per ton in the future, the costs will be significantly reduced, making the cost-effectiveness of this material more pronounced compared to other silicon-based anode materials, and the application prospects will be very broad. The publication of Huawei's silicon-based anode patents has added heat to the currently popular solid-state battery sector. As the downstream application market continues to expand and technology iterates and upgrades, the industrialization process of silicon-based anodes will gradually accelerate!