Qingdao Energy made progress in large-scale preparation of lithium-free cathode materials

Conventional lithium ion rechargeable batteries generally use an organic electrolyte. When there are abnormal conditions such as overcharging or internal short circuit, the electrolyte may be heated, and there is a danger of spontaneous combustion or even explosion. For example, the Boeing 787, known as the "Dream Airline", suffered a battery failure in 2013, and was forced to stop globally due to battery defects. Recently, Samsung has recalled 4.3 million mobile phones worldwide due to the battery "explosion door" incident. , causing major economic losses. Therefore, it is very important to develop a safe and reliable battery.

Lithium metal polymer batteries have become a research hotspot due to their high energy density, good thermal stability and high safety performance. This type of battery replaces the liquid electrolyte in a conventional lithium ion battery with a polymer electrolyte material. Because the polymer material has many advantages such as good flexibility, good viscoelasticity, easy film formation, good electrochemical and chemical stability, and high lithium ion migration number, its safety can be greatly improved. In addition, the lithium metal polymer battery uses lithium metal as the negative electrode, and its theoretical capacity is as high as 3680 mAhg-1. However, the overall capacity of the battery is still not high, which is mainly limited by the performance of the positive electrode material. Therefore, the development of a positive electrode material with excellent performance can greatly increase the capacity of a lithium metal polymer battery.

V6O13 has an octahedral structure, and each molecule of V6O13 can accommodate 8 lithium ions, thereby exhibiting a theoretical specific energy of up to 417 mAhg-1 and 900 Whkg-1. Because of its high theoretical capacity and good electron conductivity, V6O13 has been widely used as a battery cathode material. However, in the preparation process, since vanadium has a mixed valence state (V2+, V3+, V4+, V5+), there is a big challenge in the controllable preparation of the material.

Recently, the energy materials and nanocatalysis team led by Liang Hanjun, a researcher at the Qingdao Institute of Bioenergy and Processes of the Chinese Academy of Sciences, used the thermogravimetric-infrared coupling technology to successfully produce high-purity V6O13 lithium-free cathode materials on a large scale. This technology successfully demonstrates that commercial V6O13 cathode materials contain impurities that affect their electrochemical performance. The lithium metal polymer battery with the prepared V6O13 as the positive electrode material was subjected to charge and discharge experiments at a high temperature of 125 ° C. The experimental results show that the high-purity V6O13 obtained by large-scale preparation has a discharge capacity of V6O13 compared with the commercial V6O13 during the initial discharge. Increased by nearly 10%, a good description of the structure-activity relationship between the purity of V6O13 and its electrochemical properties. In addition, the high-temperature test results of the battery prove that it can be used as an oil and gas well underground power source in oil and gas field logging tools. Related results are published in ACS Applied Materials and Interfaces (ACS Applied Materials & Interfaces, 2016, 8, 25674-25679).

Infrared 3D image of NH4VO3



Commercialized V6O13 infrared 3D map



Infrared 3D image of V6O13 prepared on a large scale



Commercialized (left) and large-scale preparation (right) V6O13 discharge curves