What progress has been made in Qingdao Energy series in the solid lithium battery field?

The fire accidents of Tesla electric vehicles have occurred one after another. Several domestic incidents have been very serious. Even the entire vehicle has been severely burned, allowing people to re-examine the safety of commercial lithium-ion batteries. Liquid organic electrolytes in traditional lithium-ion batteries are the main culprits of combustion and explosion hazards. Although the battery management system can ensure the consistency and safety of the battery to a certain extent, when the external force collides to cause the puncture, the explosion of the lithium ion battery fire is inevitable. Obviously, this can not be solved by simple external battery management or physical peripheral protection. It is necessary to theoretically break through the design concept of lithium batteries so as to fundamentally improve the safety of lithium batteries.

The use of solid electrolytes to replace traditional liquid electrolytes is considered to be the only way to essentially improve the safety of lithium batteries. However, due to a series of scientific problems such as solid interface compatibility and immature solid electrolyte scale preparation technology, there has been no commercial high-energy density solid lithium battery. Relying on the Qingdao Institute of Bioenergy and Process Research Institute of the Chinese Academy of Sciences, the Qingdao Energy Storage Industry Technology Research Institute(abbreviation: Qingdao Energy Storage Institute), with the support of the Chinese Academy of Sciences Nanotopic, has been exploring and exploring for many years, and has achieved high energy density solid state lithium batteries. Progress has been made at different stages. A series of progress has been made in the field of basic research, and 42 SCI papers have been published. In the demonstration of the industrialization of high-energy density and high-security deep solid lithium batteries across the sea, the key core technologies for long-term power supply throughout the sea have been captured. The 11000-meter pressure tank test and the full-sea depth demonstration application have been achieved to boost the country's deep-sea power supply to a new height.

Solid electrolyte is the core component of solid lithium-ion batteries. The research and development of solid electrolyte system with excellent comprehensive performance is the core and bottleneck of the system to improve battery performance. However, inorganic materials or polymer materials, single materials alone can not meet the requirements of high-capacity batteries for the comprehensive performance of Ionic conductivity, mechanical strength, and thermal stability. In order to solve this difficult problem, the Qingdao energy storage Institute put forward the design concept of "rigid and flexible" solid polymer electrolytes, and used the advantages of different materials to innovatively compound "rigid" porous skeleton materials and "flexible" polymer ion transfer materials. Through the advantages and complementarities of rigid and flexible materials, combined with the Lewis acid-base interaction to increase the segmental motion and enhance the interface ion transmission characteristics, a number of solid polymer electrolytes with excellent comprehensive performance were prepared to meet the requirements of long endurance and high safety solid lithium batteries. The series of results has been published in ACSappl.Mater.Interfaces, 2017, 9,3694; Electrochim.Acta, 2017, 225, 151; J. Mater.Chem.A, 2016, 4,5191; Chem.Mater. , 2017, 236,221; Apple.Mater.Interfaces, 2017, 9,8737; Adv.Sci.. , 2017, DOI: 10.1002 / advs. 2017 00174; J. Mater.Chem.A, 2017, 5, 11124 and other academic journals.

Ion conduction between solid electrolytes and electrodes is related to the success or failure of solid lithium batteries. In order to effectively reduce the interface impedance, inspired by the "SEI membrane", the Qingdao Energy Storage Institute proposed the "in-situ self-formation" mechanism. First, the liquid monomer molecule infiltrates the electrode interface and then polymerized it in situ into a polymer solid electrolyte. This "in-situ self-formation" system effectively solves the solid interface ion conduction while improving the distribution of lithium ions at the interface to inhibit lithium dendrites. The results are published in Adv.Sci. , 2017, 4,160377; 2017, DOI: 10.1002 / manuscript No. advs. 2017 00174. Based on this concept, the integrated solid state sodium battery built by Qingdao Energy Storage Institute can effectively reduce the interface impedance and widen the electrochemical window, greatly improving the long-term cycle stability of solid state sodium batteries. At the same time, the "in-situ self-formation" method was further extended to the application of Gaodianya positive electrode and the in situ protection of lithium metal negative electrode. The series of results were published in Small, 2017, 13,1601530; J. Mater.Chem.A. 2017, 5,11124; Chem.Mater.2017, 29,4682.

In the practical application of solid-state batteries, extrusion and puncture are inevitable. How to deal with the resulting fixed interface failure is very necessary. The Qingdao energy storage house has constructed a solid battery system with "cooling recovery" function by using the gelation process of thermal reversible polymer temperature response(Figure 2). After being strongly squeezed or folded, although the contact between the electrolyte and the electrode is destroyed and the battery performance plummet, the battery performance can be restored efficiently through a simple low-temperature cooling step to reshape the effective solid interface. The results are published in Angew. Chem.Int.Ed. 2017, DOI: 10.1002 / anie.201704373. In the integration and trial of large-capacity devices for solid-state lithium batteries, Qingdao Energy Storage Institute has broken through the technical bottleneck of high-energy density solid-state lithium batteries: successful development of large-capacity solid-state lithium batteries; The third-party detection energy density of the National Chemical Power Testing Center reached 300 Wh/kg, and the recycling life exceeded 500 times; Moreover, their further development of the polymer heating flow will cut off the short-circuit point to ensure safety performance. Multiple pinning experiments have shown that the battery has excellent safety and self-repair characteristics(Figure 2).

In March 2017, the "Qingneng-I" solid state battery developed by the Qingdao Energy Reserve Institute went to the Mariana Trench with the Chinese Academy of Sciences Abyss Examination Team to provide energy for the "Wanquan" lander control system and CCD sensor, and successfully completed 10,000 meters. Full deep-sea demonstration application. It marks that the Chinese Academy of Sciences has broken through the bottleneck of the full-sea deep power supply technology and mastered the core technology of the full-sea deep power supply system. This technology will provide technical support for the development of the high-performance long endurance power supply system represented by the "Dragon"special. Related achievements and technologies have applied for 29 Chinese invention patents and 3 international PCT patents.

The above work was supported by the National Outstanding Youth Fund, the Nano Special Project of the Chinese Academy of Sciences, the Deep Sea Power Project of the Chinese Academy of Sciences, the Shandong Provincial Forward-looking Special Fund, and the Qingdao Storage Energy Institute Think Tank Joint Fund.

The page contains the contents of the machine translation.