Kaijin Energy Technology Co Ltd Sodium Ion Battery Technology
Kaijin Energy Technology Co Ltd based in Dongguan, China, was founded in March 2012. It is a high-tech enterprise in China specialising in R&D, production, and sales of anode materials for mobility, energy storage and portable electronics. Kaijin’s anode materials are designed to have high capacity, high temperature performance, excellent cycling performance and good safety performance. The products cover anode materials for square, cylindrical, soft pack polymer and other types of lithium-ion batteries.
Kaijin’s recent patent applications describe a technology for self-filling pores of a merchant graphite material using negative pressure. The work looks to overcome the challenges of utilising silicon in anodes i.e., volume expansion and resultant cracking and chalking which cause the anode material to lose contact with the current collector, resulting in a sharp decline in cycle performance.
In addition, silicon material has low intrinsic conductivity which leads to poor rate performance. The patent applications (CN112563501 A, CN112563503 A) describe a production method which makes a silica phase by spray pyrolysis to form silica nanoparticles and mixes those with a dispersing agent and a binder in a solvent to obtain a uniformly dispersed precursor. Secondly a “puffed/emulsified” graphite is prepared. This material is more commonly known as “expanded graphite” and is multiporous with pores as large as 2 mm which can easily be intercalated by polymeric materials to form composites. (Zheng, Yu, & Yang, CN112563501A, 2021a), (Zheng, Yu, & Yang, 2021b) The expanded, emulsified graphite is added to the dispersed silica precursor under vacuum which forces the silica precursor into the graphite’s pores. This gives a paste which is spray dried and mixed with carbon coating material, calcined, and screened to the desired size to provide an anode material with a pomegranate appearance and a garnet structure. The material obtained is claimed to provide an anode with a high initial efficiency, low volume expansion, improved conductivity, rate performance and long cycle life. The carbon coating on the outside layer also prevents direct contact between the nano silicon and the electrolyte.
Preparation methods which overcome the outstanding issues with cracking, and which can be scaled cost effectively provide a significant competitive advantage for anode manufacturers. High tech enterprises are on the forefront of such innovations.
Other KAIJIN patent filings including WO2022121137A1 describe preparation processes for one-dimensional porous silicon-carbon composite anode materials with good performance in terms of reversible specific capacity and cycle stability. The materials are prepared by using nano-SiO2 with polyacrylonitrile processed using electrospinning which results in a material with a shorter lithium-ion transmission distance and lower volume expansion problem, improved structural properties and cycling characteristics. (Ge & Yang, 2022)
Tests on the material indicated that reversible capacity of the silicon/carbon composite material can be selectively regulated by the amount of silicon source introduced. A first reversible specific capacity greater than 750 mAh/g was obtained, the first cycle coulombic efficiency was greater than 86% and the capacity retention was 84% after 100 cycles.
Ge, C., & Yang, Y. (2022, June 16). WO2022121137A1. One-dimensional porous silicon-carbon composite negative electrode material, preparation method, and application thereof.
HiNa Battery. (2018). R&D Achievements. Retrieved from HiNa Battery: https://www.hinabattery.com/en/index.php?catid=15
Nannan, Z. (2019, April 1). China First Demonstrates the 100 kWh Na-Ion Battery System for Energy Storage. Retrieved from Chinese Academy of Sciences: https://english.cas.cn/newsroom/research_news/201904/t20190401_207399.shtml
Wu, K., Dou, X., Zhang, X., & Ouyang, C. (2022). The sodium-ion battery: An energy-storage technology for a carbon-neutral world. Engineering, Pre-proof.
Zheng, A., Yu, D., & Yang, Y. (2021a, Mar 26). CN112563501A. Pomegranate-like structure silicon-based composite material, and preparation method and application thereof.
Zheng, A., Yu, D., & Yang, Y. (2021b, March 26). CN112563501A. Pomegranate-like structure silicon-based composite material, and preparation method and application thereof.