BYD's latest patent for all-solid-state batteries is disclosed!

According to information from the National Intellectual Property Administration, BYD has published a patent titled "All-solid-state batteries , battery packs and electrical equipment" (hereinafter referred to as "Patent 1"), with publication number CN 118748295 A. The inventors are Shi Hongbing, Wang Guoshuai, Guo Zizhu, You Maolin and Shi Zhuo. The application publication date is October 8, 2024, and the application date is August 7, 2024.

Photo/State Intellectual Property Office

The abstract shows that the all-solid-state battery of Patent 1 includes staggered stacked negative and positive electrodes, a solid electrolyte layer between the negative and positive electrodes, and the outermost negative electrode. Among them, the outermost negative electrode includes a negative electrode current collector and a negative electrode active material layer and a ceramic layer respectively arranged on the two sides of the negative electrode current collector, and the ceramic layer is located on the side of the negative electrode current collector away from the positive electrode.

The technical innovation of Patent 1 lies in that the outermost layer of the battery is designed to be a ceramic layer, and the good rigidity and hardness of the ceramic layer itself are utilized to ensure uniform force when the battery is subjected to a large pressure during the isostatic pressing process, so that the pressing surface is flat, the outer packaging film is not easily broken, and the battery will not be torn during the subsequent restraint and pressurization process, so that the battery has good initial efficiency and cycle performance.

According to the specification, the ceramic layer of the all-solid-state battery of Patent 1 meets at least one of the following four conditions: Mohs hardness of 3~10, Poisson's ratio of 0.1~0.5, density of 50%~90%, and elastic modulus of 2~10GPa, and the thickness of the ceramic layer is 30μm~150μm.

A patent related to all-solid-state batteries has been published

Veken Lithium also noted that on August 7 this year, BYD also applied for a patent called "All-solid-state battery, battery pack and power-consuming equipment" (hereinafter referred to as "Patent 2"), with the publication number CN 118589111 A. However, the application publication date of this patent is September 3, 2024, and the inventors are Shi Hongbing, Wang Guoshuai, Guo Zizhu, Ren Jincan and Zhao Xiaolei.

In addition, Patent 2 is different from Patent 1 in that one of the two sides of the outermost negative electrode current collector is a negative electrode active material layer and a flexible buffer layer, and the other is a negative electrode active material layer and a ceramic layer.

Photo/State Intellectual Property Office

The abstract shows that the all-solid-state battery of Patent 2 includes staggered stacked negative and positive electrodes, a solid electrolyte layer between the negative and positive electrodes, and the outermost negative electrode. The outermost negative electrode includes a negative current collector and a negative active material layer and a flexible buffer layer respectively disposed on both sides of the negative current collector, and the flexible buffer layer is located on the side of the negative current collector away from the positive electrode.

The technical innovation of Patent 2 lies in that the outermost layer of the battery is designed as a flexible buffer layer, and the good flexibility of the flexible buffer layer itself is utilized to make the pressure distribution of the battery uniform during the restraint and pressurization process, thereby improving the initial efficiency and cycle performance of the battery.

According to the specification, the flexible buffer layer of the all-solid-state battery of Patent 2 meets at least one of the three conditions of elastic modulus of 0.5~6Gpa, Poisson's ratio of 0.05~0.5, and elongation of 2%~15%, and the thickness of the flexible buffer layer is 5~50μm.

Fudi Battery's solid-state battery plan

BYD is the company with the largest number of solid-state battery patents in my country. With the announcement of the above two all-solid-state battery patents, BYD's solid-state battery patent group has further expanded.

At present, BYD has not released any solid-state battery related products, but in June this year, the latest solid-state battery plan of its subsidiary Fudi Battery was exposed.

It is reported that from the perspective of technical route, Farasis Battery is very likely to have chosen the technical route of high-nickel ternary (single crystal) + silicon-based negative electrode (low expansion) + sulfide electrolyte (complex halide).

Fudi's solid-state battery cell capacity can reach more than 60Ah, the mass energy density reaches 400Wh/Kg, the volume energy density reaches 800Wh/L, and it will not catch fire or explode when punctured or hot-boxed. At the same time, taking into account the battery system and vehicle efficient integration technology under the performance requirements of thermal management, safety, and fast charging, the battery pack energy density exceeds 280Wh/Kg.

Materials In terms of cost control, the cost reduction plan for sulfide (or sulfide + halide composite) solid electrolytes, which account for the absolute cost proportion, is to reduce the cost of LiS by 1500%-2000% by 2027 compared with the cost reduction effect in 2024. In 2030, through the improvement and optimization of the synthesis process, the cost will be reduced by another 30%-50% compared with 2027. In 2033, the cost will continue to be reduced by about 20%-30% through scale efficiency.

After reducing costs through solid-state electrolytes, the overall material BOM cost is planned to be reduced by 2000%-3000% by 2027, and then the manufacturing cost will be reduced by 30%-50% by improving product yield + scale effect + process optimization.

In terms of mass production time, the report said that Fudi's plan is consistent with national policies and most companies. It will start small-scale production in 2027 and be installed on BYD's high-end models as a demonstration project with a scale of only about 1,000 units; 2030 is the market promotion period, and it is expected that 40,000 vehicles will be equipped with all-solid-state batteries, and will begin to move down to models in the mainstream price range; 2033 will enter a rapid expansion period, and it is expected that 120,000 vehicles will be installed on a large scale, and the market share of all-solid-state batteries will gradually increase.

In fact, there was news in 2022 that BYD's all-solid-state lithium battery was produced in Chongqing and was about to be installed for testing. Although BYD denied the news at the time, some of the content was consistent with the information disclosed by Fudi this time.

It is understood that news in 2022 revealed that BYD's solid-state battery mainly adopts oxide and sulfide technology routes, uses silicon-based materials as the negative electrode, and the energy density is expected to reach 400Wh/kg.

It is worth mentioning that the news also mentioned that in addition to BYD's own use, BYD's first batch of all-solid-state batteries will also be supplied to other companies.

In general, there is more and more news about BYD's solid-state batteries. As to whether it can be mass-produced in 2027, we have to wait and see.