Electric Hydrolysis of Tungsten Trioxide /Tungsten Oxide

Tungsten trioxide is an important type of N type semiconductor oxide. It is widely used in chemical sensors, photocatalysis, energy conversion system and other fields. When WO₃ is used as negative material, its structure and volume will change greatly during charge / discharge process. It destroys the stability of electrode materials and eventually leads to the cyclic performance of the electrode. As a result, the actual capacity is often lower than the theoretical capacity.

In order to overcome the existing problems in the existing technology, the researchers produced a tungsten trioxide / tungsten oxide composite material which can be used as negative electrode for lithium ion batteries. The preparation methods include the following steps:

(1) 0.5M C₆H₈O₇•H₂O distilled water solution and 0.5M Na₂WO₄•2H₂O distilled water solution were prepared.

(2) The solution was mixed at a volume ratio of C₆H₈O₇•H₂O:Na₂WO₄•2H₂O = 2:1 and stirred 15min at 25°C.

(3) The mixed solution pH = 1 was adjusted with HCl solution of 2M.

(4) The mixed solution was poured into the Teflon lined high pressure hydrothermal reactor to maintain the volume filling ratio of 40%.

(5) The sealed reactor was put into the homogeneous hydrothermal reaction apparatus, and the temperature parameter was set at 160°C and the reaction time was 28h.

(6) After the reaction was cooled to room temperature, the final reactants were centrifugally separated and washed with deionized water and absolute alcohol for 3 times. After centrifugation and washing powder was put into vacuum drying oven at 60°C for drying 10h, the final product was obtained.

According to the electric hydrolysis of tungsten trioxide / tungsten oxide test, the current density of 100mA/g circulate 500 times, the efficiency can reach 95%. With the reduction of citric acid, the reduction of the tungsten part makes it have a higher theoretical capacity. Due to the oxygen vacancy defect in the two tungsten oxide lattice and the strong metal metal bond inside the crystal, tungsten oxide (WO₂) has metal conductivity (electronic conductivity is about 3.5 x 102S/cm), the metal conduction of tungsten oxide is used. As a conductive oxide and WO₃, it can solve the problem of large volume change in the cycle of tungsten trioxide, so as to improve the specific capacity, reduce the volume change in the cycle process, improve the discharge capacity of WO₃, and reduce the charge transfer resistance of WO₃, so that tungsten trioxide can reach the energy conversion standard.

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