The Ministry of Industry and Information Technology Lithium-ion Battery and Similar Products Standards Working Group held the "Sodium-ion Battery Industry Chain and Standard Development Forum" on November 28~29. The forum was hosted by the China Electronics Technology Standardization Institute and Zhongguancun Energy Storage Industry Technology Alliance, and participated by enterprises and institutions related to sodium-ion batteries.
The conference aims to build a communication platform for sodium-ion battery industry chain enterprises, and also provide a window for relevant personnel in the sodium-ion battery industry to understand the latest information of the sodium-ion battery industry. Enable participating enterprises and institutions to strengthen cooperation and exchanges and promote the healthy and sustainable development of sodium-ion battery industry. During the period, 18 industry leaders discussed the development status and market prospects of sodium-ion batteries.
Liu Zhongbo from Shenzhen Xinzhubang Technology Co., Ltd. delivered a keynote speech on "Development of Matching Electrolyte for Sodium-ion Batteries" at the Sodium-ion Battery Industry Chain and Standard Development Forum.
The speech mainly focused on four aspects: the future prospects of sodium-ion batteries, the comparison of lithium/sodium battery electrolytes, the development thinking and research progress of sodium-ion battery electrolytes, and the industrial layout of Xinzhoubang.
The development history of sodium-ion batteries is introduced, since 1970 began to study sodium-ion batteries, in the 90s the research on sodium-ion batteries was temporarily shelved, and in 2011 continued the research of sodium-ion batteries, sodium-ion batteries ushered in rapid development.
Compared with lithium iron phosphate batteries, sodium-ion batteries have the advantage of better rate, and the capacity release rate at different temperatures is also better, and the performance of sodium-ion batteries is better at low temperatures.
Compared with lithium-ion batteries, sodium-ion batteries have advantages in cost, low temperature, rate, safety and system integration efficiency. It has shortcomings in energy density and long cycle life, and has good application prospects in energy storage, low-speed vehicles, industrial batteries and other fields.
The benefits of sodium-ion batteries exist in many aspects, including more secure resources, huge potential markets, favorable global policies, and lower theoretical costs.
In the second part of the presentation, the electrolyte of lithium batteries and sodium batteries was compared.
Compared with the basic physical properties of sodium and lithium electrolyte, the chromaticity of sodium electrolyte is almost four times that of lithium electrolyte, the turbidity difference is more than 20 times, and the flash point of sodium electrolyte is stable than that of lithium electrolyte by 4.8 °C.
Comparison of thermal weight loss of sodium electro/lithium electrolyte, it was found that the thermal stability of sodium hexafluorophosphate itself and the electrolyte based on it showed better thermal stability.
Comparison of the quality of sodium battery/lithium electrolyte, when sealed and stored, the water acidity change of lithium battery and sodium electrolyte is similar, but the color of sodium ion battery electrolyte is relatively stable; In a humid environment, the electrolyte stability of sodium-ion batteries is better.
The third part of the speech was the development of electrolytes for sodium-ion batteries and research progress.
Xinzhoubang sodium-ion batteries focus on layered oxide/hard carbon systems. Because the technical maturity of the system is high. Compatible with the existing process system, it is one of the fastest systems to be introduced.
Due to the shortage of O3-type layered oxides, Fe ions will be transferred to the Na layer, which is irreversible; In the case of high capacity and high pressure, oxygen evolution phenomenon exists in the positive electrode; The phase transition technology of elemental doping inhibition materials is not fully mature; The radius of Na ions is larger than that of lithium ions, and the stress embedded in the detachment process will lead to the fragmentation of particles; The surface of the cathode material is highly alkaline.
Through the typical XRD and SEM diagrams of graphite and hard carbon, we can see that the physical properties and electrochemical differences between graphite and hard carbon are obvious, and the existence of slope area requires the electrolyte to change the design concept.
The sodium phosphate layer present in the SEI membrane structure of sodium electricity is very different from the mosaic model of lithium battery. It can be seen that FEC additives have a very obvious effect on improving the stability of SEI films.
The design of electrolyte for sodium-ion batteries considers that in terms of cathode, there are similar requirements for high nickel cathodes, and the alkalinity tolerance and improvement of cathode stability requirements are changed; Negative electrode; There are double references of supercapacitors and graphite, as well as dual consideration of capacity in slope area and platform area; In terms of SEI membrane, it is necessary to improve the stability and structure of SEI membrane, and increase the means for electrolyte to regulate SEI membrane.
In order to improve the electrolyte of sodium-ion battery, there is an innovative design of ether-based electrolyte to adjust the solvation structure and improve the kinetics of sodium ion transport. Based on the customized design of the formula, it realizes the collaborative modification of multi-level and multi-element interface films, inhibits the occurrence of positive electrode defects, isolates interface side reactions, and stabilizes the material structure; In view of the catalytic decomposition of electrolyte due to surface defects of cathode materials after delithiumization, the occurrence of cathode defects is inhibited by the special design of the electrolyte, and the adsorption process of the solvent by the defect can be suppressed, thereby inhibiting gas production.
On the basis of the traditional lithium battery composition formula, the combination of traditional carbonate solvent and sodium salt additive can achieve a great improvement in performance by optimizing the formula, and the cycle life can be more than doubled.
In terms of the use of new solvent to improve performance, SCT2673 solvent showed an overall improvement of sodium-ion batteries, especially the cycle improvement.
In terms of improving battery cycle performance and gas production, SCT2584 and SCT2582 are potential additives, SCT2582 can improve battery high temperature cycle, SCT2584 can improve cycle performance, rate performance and effectively inhibit high temperature cycle gas production.
Shenzhen Xinzhoubang Technology Co., Ltd. began to develop sodium-ion battery electrolyte in 2016, Neralyte series sodium-ion battery electrolyte has been released, the scope of application includes basic chemical principles, electronic chemicals, electronic components, batteries, capacitors, etc., 3C digital products, energy storage, medicine and other aspects.
Neralyte series sodium-ion battery electrolyte has good effects in improving the magnification, improving circulation, and inhibiting gas production.
At present, Shenzhen Xinzhubang Technology Co., Ltd. has completed the process development of tonn-level production of sodium-ion batteries, and the new additives and solvents of sodium electricity are planned for mass production in Jiangsu Hankang and Hunan Fubang.
Finally, Shenzhen Xinzhubang Technology Co., Ltd. thanked Southern University of Science and Technology, China Science and Technology Haina, Shanghai Jiaotong University, and Nachuang for their assistance in the research and development process.
The above is the keynote speech of "Development of Matching Electrolyte for Sodium-ion Batteries" delivered by Shenzhen Xinzhoubang Technology Co., Ltd. at the sodium-ion battery industry chain and standard development forum. Interested parties can contact Shenzhen Xinzhoubang Technology Co., Ltd. for details.