Nanocrystals of tungsten disulfide may improve the safety of power batteries

    Compared with other materials, low-dimensional disulfide nanocrystals are widely regarded as a promising cathode material for lithium ion batteries due to their layered structure and large surface area.Compared with the commercial anode materials, the cathode containning sheet-shape nanometer ws2 material of lithium ion diffusion ability is stronger, and better chemical stability and thermal stability, is not easy for the charging and discharging lithium ion on the surface of the material, emergence and embedded with obvious deformation, but also can effectively reduce the probability of thermal chemical reaction with the electrolyte solvent.Therefore, it shows that the tungsten disulfide nanocrystals can improve the safety of power battery to a certain extent.

    So why are power batteries safe?

    The safety of power battery is the most difficult and intractable problem in all contradictions, which involves all aspects.

    Lithium battery is a kind of energy storage device, energy can be divided into two parts: one is reversible conversion, at both ends of the charge and discharge reversible;The second is its own energy consumption, in the oxidation reaction can release heat.Under normal circumstances, the battery charge and discharge or energy conversion speed can be controlled, but in the form of electrical energy, in the event of a short circuit, the energy release rate is very fast, which can lead to heat a large number of accumulation, when the rate of uncontrolled will explode, that's why lithium batteries will be the root cause of accidents.

    There is a trigger mechanism for the battery to lose control of heat. First, the cathode material itself is decomposed, which generates heat. In turn, the positive excitation leads to uncontrollable energy release, which eventually causes the battery to explode and burst into flames.So how do you keep batteries from getting out of control?The first is the choice of raw materials, as far as possible to choose a higher level of safety or less energy release materials for the battery;Secondly, from the perspective of battery design, battery safety accidents are mostly caused by battery defects.

    Factors affecting the safety of power battery include :(1) energy density.In general, the higher the energy density of materials, such as 811 high nickel materials, the lower the thermal stability;(2) Quick charge.Because fast charging requires a large current to charge the electric vehicle, which means that the faster the charging speed, the internal temperature of the battery is easy to jump, and the greater the potential safety hazard of the battery will be.

    Therefore, in order to improve the safety of power batteries, some researchers have suggested that tungsten disulfide nanometer sheets should be used to produce high-performance negative electrode materials.This is mainly due to the disulfide not only has a higher theoretical specific capacity density, but also has a higher melting point and better corrosion resistance. As a negative production material, it can well avoid the reaction between the product and electrolyte.In addition, as a layered material, tungsten disulfide nanocrystals are very favorable for the movement of lithium ions, which in turn can effectively slow the temperature rise rate of rechargeable batteries under high current.

    Nowadays, with the continuous improvement of people's safety awareness and the development of new energy industry, flake tungsten disulfide nanomaterials are expected to be the preferred materials to alleviate the safety problems of power batteries.