Qingdao Institute Of Bioenergy And Process Research (QIBEP) Makes Series Of Progress in The Field Of Low-cost And High-security Sodium-ion Batteries

In China's "14th Five-Year Plan" and "Guiding Opinions on Accelerating the Development of New Energy Storage", it is proposed to accelerate the research and development of sodium-ion batteries and other technologies, as well as to carry out large-scale experimental demonstrations. This fully demonstrates that sodium-ion battery technology research and development has risen as a national strategy. Compared with the scarcity of lithium resources, sodium in China's abundant reserves, the price is cheaper, so the sodium-ion battery in the field of large-scale energy storage has a broad application prospects. However, the current industrialization of sodium-ion batteries still exists in the process of lower energy density, shorter cycle life and other issues, seriously limiting the further application.
The Solid State Energy System Technology Center led by researcher Cui Guanglei of Qingdao Institute of Energy, Chinese Academy of Sciences, started to lay out the sodium-ion battery in 2011, combined with the national strategic needs and basic scientific issues as a whole, based on the cutting edge, a unique way to develop a number of sodium-ion battery key materials and electrolyte key technologies, and in recent years has achieved a series of important results, laying a research foundation for the development of industrialization of sodium-ion batteries. In 2015, the technology center developed porous graphite collector and corresponding pre-sodiumation technology through laser perforation of polyimide graphite film, which significantly reduced the cost and improved the energy density of sodium-ion batteries (Electrochemistry Communications 2015, 61, 84-88; Journal of Power Sources 2015, 297, 457-463; ZL201510242864.9).In 2016, polyacrylate-based polymer electrolytes with high ionic conductivity were developed and patented by in-situ solidification (ZL201610150608.1; ZL2016112243.1). ZL201611224300.3), which improved the interfacial ion transport performance between the solid-state electrolyte and the electrode material, realizing a significant increase in the multiplicity performance of sodium batteries.In 2019, a methyl vinyl ether-maleic anhydride copolymer solid-state polymer sodium battery was constructed, and the assembled soft-packed sodium batteries can still work safely under the harsh conditions of bending or corner-cutting, without leakage or fire hazards. No liquid leakage or fire hazard occurs (Nano Res. 2019, 12, 2230-2237; ZL201911259343.9; ZL201911357076.9). 2022, in order to further improve the safety of the electrolyte, the technology center designed and developed a new flame-retardant phosphate ester formula that takes into account the stability of the high voltage. In 2022, in order to further improve the safety of electrolytes, the center designed and developed a new phosphate ester flame retardant formulation with high voltage stability (ACS Appl. Mater. Interfaces 2022, 14, 15, 17444-17453) and an intrinsically safe, green and low-cost aqueous electrolyte (ACS Appl. Mater. Interfaces 2022, 14, 29, 33041-33051; ZL202011357076.9). -33051; ZL202011071670.4; ZL202111281780.8).
Recently, the Solid State Energy Systems Technology Center has made significant progress in the field of low-cost sodium-ion batteries, and the research results have been published in the international authoritative journals Angew. Chem. Int. Ed., Adv. Energy Mater. and Energy Storage Mater. (Fig. 1). In response to the problems of hydrogen precipitation and electrode metal ion dissolution caused by free water molecules in the traditional aqueous electrolyte, the research team obtained a new system of ultra-high concentration polymer electrolyte for sodium-ion batteries through the regulation of hydrogen bonding by methylation, and the cycling stability of sodium batteries achieved a breakthrough improvement (Angew. Chem. Int. Ed. 2023, e202311589). At the same time, the research team found that NaH in the sodium metal anode SEI is a major factor affecting the performance of the battery, which is an important mechanism leading to the failure of sodium batteries, and that NaH is generated by the spontaneous reaction between the hydrogen generated in the battery cycle and the deposited sodium metal (Energy Storage Mater. 2023, 61, 102891). The research team further summarizes the fundamental principles and research progress in the current electrolytes for sodium-ion batteries, and looks forward to the future development of electrolytes (Adv. Energy Mater. 2023, 2301758).

Fig. 1 Progress of basic research on sodium-ion batteries in Solid State Energy System Technology Center.
Based on the above research foundation and technology accumulation, after more than ten years of efforts, the Solid State Energy System Technology Center led by researcher Guanglei Cui has successfully developed low-cost, high-safety and high-performance solid-state sodium-ion batteries. The currently developed solid-state sodium-ion battery has an energy density of more than 140 Wh/kg in the electric core and a specific energy density of more than 110 Wh/kg in the battery module; it has ultra-high safety, which can pass the pinprick test without smoke, combustion, or explosion, and has been realized in the demonstration application of two-wheeled electric vehicles (Figure 2). In the future, the team will continue to develop key materials and core technologies for sodium-ion batteries to meet the market needs in accordance with different application scenarios, focusing on low-speed electric vehicles, new energy vehicles 48 V power supply systems, home energy storage and other fields.