We have developed an Non-negative sodium ion battery with an energy density of up to 500wh/Kg. The composite collector is fabricated using the atomic layer deposition method, and sodium ions can be uniformly and smoothly deposited on the surface of the collector. At the same time, the soft elasticity design ensures that the sodium ions are in close contact with the internal structure of the battery during the deposition and stripping process.

At the same time, the company has researched the solid-state sodium ion battery, which has good safety performance, can pass the pinprick test, has an energy density of up to 450Wh/Kg, and has a cycle of up to 2,000 times or more. It adopts sulfide solid electrolyte with high conductivity and strong adaptability to ensure that the battery can have good multiplication performance as conventional liquid batteries. Meanwhile, it adopts artificial SEI technology and 3D sodium negative technology to ensure the interfacial stability between sodium metal and solid electrolyte and avoid the problem of holes on the anode surface of conventional sodium-ion solid state battery.

Among many anode materials for sodium-ion batteries, hard carbon has the advantages of abundant raw material sources, non-toxicity and environmental protection, small volume change of de-embedded sodium, and low sodium storage potential, etc. Thanks to the rich sodium storage environment (including graphite interlayers, closed micropores, surface and defect sites), its theoretical sodium storage capacity is as high as over 530 mAh/g. At present, hard carbon, as an anode material for sodium-ion batteries, mainly faces three problems: higher preparation cost, low first-time coulombic efficiency, and poor multiplicity performance. Commonly used hard carbon precursors are biomass and its derivatives, with low raw material cost and high capacity, but low carbonization yield (about 30%) and more complex treatment process, resulting in poor economy (Japan's Kuraray's coconut shell-based hard carbon is priced at 200,000 yuan/ton). There are two main development directions to reduce the preparation cost: one is to develop biomass-based industrial products as raw materials, improve the yield and maintain the consistency of raw materials, and then reduce the process cost; the second is to develop low-cost surface treatment technology, taking into account the performance regulation and cost control. The enhancement of hard carbon materials for the first time the Coulomb efficiency and multiplicity of performance based on reasonable control of defects and layer spacing, and the construction of fast dynamics of the reaction interface, the development of the direction of the main four: one is to regulate the carbonization process of the precursor (carbonization temperature, rate of change of temperature, carbonization mode, etc.) or doping of hetero-atoms, in the microscopic control of the pore structure of the hard carbon and the spacing of the layers; the second is to through the surface of the surface coating, composite, etc., the surface structure of the material on the macroscopic control; the second is the development of low cost surface treatment technology, taking into account the cost control. The second is to regulate the surface structure of the material by surface coating and composite, etc.; the third is to develop mixed solvent electrolyte or electrolyte additives to regulate the diffusion rate of sodium ions and the structure of the SEI membrane; and the fourth is to carry out pre-sodiumation treatment to compensate for the irreversible loss of active sodium ions.

The electrolyte, as an important component of sodium-ion batteries, is not only the only medium for charge transfer between the positive and negative electrodes, but also determines the maximum reversible capacity that can be realized by the battery. Currently, the commercial sodium ion battery electrolyte has a single formulation, mainly using sodium hexafluorophosphate (NaPF6) as the main sodium salt (NaClO4 is less feasible for industrialization due to its explosive and strong oxidizing properties), and ester-based EC or PC as the main solvent, supplemented by 5% FEC as the electrode interfacial film-forming additive. Although it can basically meet the current needs of material characterization and device assembly, it still faces problems such as poor compatibility of positive and negative electrodes, narrow operating temperature range and slow ion transport kinetics, which can lead to a short cycle life of sodium-ion batteries and possibly a more serious gas production phenomenon. In order to improve the many problems faced by sodium-ion batteries, 江苏浩钠新能源科技有限公司 plans to carry out the following three aspects of technological research and development based on the modification and optimization of the electrode materials and starting from the electrolyte:

1. Development of sodium ion battery electrolyte with wide temperature range: through composition optimization and adjustment of solvation structure, the low-temperature ion transport kinetics and high-temperature thermal/chemical stability of sodium ion battery electrolyte can be improved, so as to broaden the working temperature range of sodium ion battery.

2. Develop new electrolyte additives for sodium ion batteries: through the development of new electrolyte additives, a CEI/SEI film with high ionic conductivity and stable structure is derived at the positive/negative electrode interface. The aim is to passivate the positive/negative interface, weaken the side reaction, inhibit the electrode gas production and the continuous decomposition of the electrolyte, and improve the cycling stability of the sodium ion battery.

3. Customized design of sodium ion battery electrolyte: Due to the unavoidable component interaction between electrolyte and electrode materials, theoretically, there is no specific electrolyte that can be universally applied to a variety of electrode materials. Therefore, according to the current situation of diversified positive/negative electrode materials for sodium ion batteries, it is planned to customize the optimal electrolyte formula for the company's electrode material products through the combination design of sodium salt, solvent and additives.