Jiangsu Haona New Energy Technology Co., Ltd. has conducted research on some high-end cutting-edge sodium ion battery technologies. Our developed negative electrode free sodium ion battery has an energy density of up to  500wh/kg, a composite collector was manufactured using atomic layer deposition method, and sodium ions can be uniformly and smoothly deposited on the surface of the collector. At the same time, soft elastic design is adopted to ensure close contact between the internal structure of the battery during the deposition and stripping process of sodium ions.

At the same time, the company has studied solid-state sodium ion batteries, which have good safety performance and can pass needle testing. The energy density can reach up to 450Wh/Kg, and the cycle time can reach over 2000 times. The use of sulfide solid electrolyte with high conductivity and strong adaptability ensures that the battery can have good rate performance like conventional liquid batteries. At the same time, artificial SEI technology and 3D sodium negative electrode technology are used to ensure the interface stability between sodium metal and solid electrolyte, as well as to avoid the surface hole problem of conventional sodium ion solid Shenchi negative electrode.

In addition, the company has also conducted research on the technology of manufacturing sodium ion battery electrodes using thousands of methods and applied for invention patents. Unlike the dry mixing, cold rolling, and hot pressing processes currently used in Tongtang on the market, the present invention uses newly developed fibrosis equipment, slicing equipment, and Fule equipment. The newly developed fibrosis equipment consists of a deformable material groove and a ramming head, which can repeatedly hammer the powder. After hammering, the fibrosis of the adhesive is more thorough and the dispersion is more uniform. The fibrosis equipment finally compresses the dry powder into a high-pressure solid density material rod, which is fed by a servo motor on the slicer and cut into thin slices using a punching knife. Then, the thin sheets are squeezed onto the collector to form electrode plates. Finally, various types of sodium ion batteries and ion batteries are manufactured through processes such as wafer viewing, electrode ear soldering, packaging, baking, liquid injection, and formation.

Among numerous negative electrode materials for sodium ion batteries, hard carbon has the advantages of rich raw material sources, non-toxic and environmentally friendly, small volume changes in sodium removal, and low sodium storage potential. Thanks to the rich sodium storage environment (including graphite interlayer, enclosed micropores, surface, and defect sites), its theoretical sodium storage capacity is as high as; Above 530 mAh/g. At present, hard carbon, as a negative electrode material for sodium ion batteries, mainly faces three problems: high preparation cost, low first-time Coulombic efficiency, and poor rate performance. The commonly used hard carbon precursors are biomass and its derivatives, which have low raw material costs and high capacity. However, the carbonization yield is low (about 30%) and the treatment process is relatively complex, resulting in poor economic performance (the coconut shell based hard carbon from Japan's colali is priced at 200000 yuan/ton). There are two main development directions for reducing preparation costs: firstly, developing biomass based industrial products as raw materials to improve yield and maintain raw material consistency, thereby reducing process costs; The second is to develop low-cost surface treatment technologies, balancing performance regulation and cost control. The improvement of the first Coulomb efficiency and rate performance of hard carbon materials is based on reasonable control of defects and interlayer spacing, and the construction of reaction interfaces with fast kinetics. There are four main development directions: firstly, regulating the precursor carbonization process (carbonization temperature, temperature change rate, carbonization method, etc.) or conducting heteroatom doping to regulate the pore structure and interlayer spacing of hard carbon at the micro level; The second is to regulate the surface structure of materials at a macro level through surface coating, composite and other methods; Thirdly, develop mixed solvent electrolytes or electrolyte additives to regulate sodium ion diffusion rate and SEI membrane structure; The fourth is to perform pre sodium treatment to compensate for the irreversible loss of active sodium ions.

As an important component of sodium ion batteries, electrolyte is not only the only medium for charge transfer between positive and negative electrodes, but also determines the maximum reversible capacity that the battery can achieve. At present, the commercial sodium ion battery electrolyte formula is single, mainly using sodium hexafluorophosphate (NaPF6) as the main sodium salt (NaClO4 has low industrialization feasibility due to its explosive and strong oxidizing properties), ester based EC or PC as the main solvent, and 5% FEC as the electrode interface film-forming additive. Although it can basically meet the current requirements for material characterization and device assembly, it still faces problems such as poor positive and negative electrode compatibility, narrow operating temperature range, and slow ion transport kinetics. These problems can lead to short cycle life of sodium ion batteries and may cause serious gas production. In order to improve the many problems currently faced by sodium ion batteries, Jiangsu Haona New Energy Technology Co., Ltd. plans to conduct technological research and development in the following three aspects based on electrode material modification and optimization, starting from the electrolyte aspect：

1. Develop a wide temperature range sodium ion battery electrolyte: By optimizing the composition, adjusting the solvation structure, improving the low-temperature ion transport kinetics and high-temperature thermal/chemical stability of the sodium ion battery electrolyte, and expanding the operating temperature range of the sodium ion battery.

2. Develop new sodium ion battery electrolyte additives: By developing new electrolyte additives, CEI/SEI films with high ion conductivity and stable structure are generated at the positive/negative electrode interface. Strive to passivate the positive/negative interface, reduce side reactions, inhibit electrode gas production and continuous decomposition of electrolyte, and improve the cycling stability of sodium ion batteries.

3. Customized design of sodium ion battery electrolyte: Due to the inevitable component interaction between the electrolyte and electrode materials, theoretically there is no specific electrolyte that can be universally applicable to multiple electrode materials. Therefore, based on the current diversification of positive/negative electrode materials for sodium ion batteries, we plan to customize the optimal electrolyte formula for the company's electrode material products through a combination design of sodium salts, solvents, and additives.