Composite electrocatalyst material used for Li-air batteries and preparation method thereof

Abstract

A composite electrocatalyst material used for Li-air batteries and a preparation method thereof. The transition metal oxide composite electrocatalyst modified by surface conductive transition metal nitride is obtained by conducting thermal nitrogen treatment, in an ammonia atmosphere or an ammonia and argon atmosphere, for transition metal oxide powder or transition metal oxide powder pretreated by nitrogen overlying, wherein the technology of the thermal nitrogen treatment is heating up the powder at a rate of 2-10 DEG C / min to reach the thermal nitrogen treatment temperature of 300-800 DEG C, preserving heat for 10min to 2h and then cooling in furnace. By controlling the content and flow rate of ammonia and the temperature and time of sintering, the thickness of the surface transition metal nitride can be controlled selectively. The method of the invention is simple in technology, convenient for operation, low in cost and strong in controllability. In addition, the obtained composite electrical catalyst has good conductivity and stability and can reduce the charging and discharging polarization of Li-air batteries effectively. The catalyst decreases the inner resistance of batteries and has good discharge capacity. The industrialization prospect of the catalyst is good.

Description

technical field [0001] The invention belongs to the field of electrochemistry, and relates to a composite electrocatalyst material for a lithium-air battery and a preparation method thereof. Background technique [0002] Due to the increasingly prominent environmental problems and the increasingly serious oil crisis, energy conservation and new energy technologies have gradually become the focus of human attention and research hotspots. As we all know, lithium-ion battery is a very representative and competitive battery system in the field of new energy. It has been widely used in mobile phones and notebook computers, and is now an important choice for the next generation of hybrid vehicles and pure electric vehicles. However, conventional lithium-ion batteries are largely limited by their inherent limitations. Lithium-ion batteries with low energy density are difficult to meet the requirements of high energy density in fields such as electric vehicles. There is limited roo...

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Problems solved by technology

When transition metal oxides are used as electrocatalysts, their lithium-air batteries have the characteristics of high discharge capacity, good cycle performance, and good electrocatalytic performance, but the conductivity of transition metal oxides is not good, the reaction is easily terminated, and cannot play Stable electrocatalytic performance

Shanmu Dong (Chemical Communications, 2011, 47, 11291-11293) etc. will use the hydrothermal method to first convert MoO 3 The composite electrocatalyst material of MoN / NGS is obtained by loading and depositing graphene material, and then reacting with ammonia gas at high temperature. Due to the good conductivity of MoN, its discharge platform is extremely high, but its charging voltage is not effectively reduced. The catalytic performance It needs to be further improved, and as MoN, which plays an electrocatalytic role, compared with transition metal oxide materials, the discharge specific capacity of its battery needs to be further improved.

[0006] Chinese patent CN 102306808A discloses a catalyst for air electrodes, using manganese salts and silver salts as raw materials, carbon materials as carriers, and ball milling to obtain a composite electrocatalyst material of carbon-supported manganese oxide and silver. The catalytic performance has been improved; however, the composite electrocatalyst material obtained by ball milling physical mixing has uneven distribution of manganese oxide and silver, and its performance needs to be further improved.

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