Core-shell structure electric catalyst material for lithium air batteries and preparation method thereof

Abstract

The invention relates to a core-shell structure electric catalyst material for lithium air batteries and a preparation method thereof. The electric catalyst material comprises a core layer formed by a transition metal oxide and a shell layer formed by a transition metal nitride, the core layer is a hollow or solid core, the inner diameter of the core layer is 0-50nm, the outer diameter of the core layer is 30-500nm, the thickness of the shell layer is 10-200nm, and the mass of the shell layer accounts for 10-40% of the mass of the electric catalyst material. The preparation method includes that the hollow or solid transition metal oxide is prepared by adopting a liquid phase method. On the basis, transition metal salt is nitrogenized directly to be covered on the surface of the transition metal oxide by adopting a nitriding sintering method, and the core-shell material is prepared by covering the transition metal nitride on the transition metal oxide. The core-shell material has good electrical conductivity and stability, can effectively reduce charging and discharging polarization of the lithium air batteries, reduces internal resistance of the batteries, has good discharging capacity simultaneously, is simple in preparation process method, convenient to operate and low in cost, and achieves large-scale production easily.

Description

technical field [0001] The invention belongs to the field of electrochemistry, and relates to a core-shell structure 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 ...

AI Technical Summary

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. used ammonia reduction method to reduce MoO 3 It is reduced to MoN as an electrocatalyst. Due to the good conductivity of MoN, its discharge and discharge platform is extremely high, but its charging voltage has not been effectively reduced, and its catalytic performance needs to be further improved.

Yi-Chun Lu (Journal of the American Chemical Society, 2010, 132, 12170-12171) et al. prepared noble metal nano-electrocatalyst PtAu / C and applied it to lithium-air batteries. The research results show that the discharge voltage of the battery has been significantly improved ( It is about 0.2V higher than pure carbon), the charging voltage is greatly reduced (about 0.6V lower than pure carbon), and the charging and discharging efficiency of the battery is significantly improved. The performance is not very ideal, and it is not easy to be commercialized on a large scale

[0006] Chinese patent CN 102240574 A discloses a catalyst composed of a transition metal complex and a carbon black carrier. The lithium-air battery prepared by using the catalyst exhibits good catalytic activity and stability, but the charging of the battery under high current density The discharge behavior is not ideal, and the hydrothermal method used cannot control the morphology of the catalyst; Chinese patent CN 102306808 A discloses a catalyst for air electrodes using manganese salts and silver salts as raw materials and carbon materials as carriers to prepare carbon-supported oxidation Manganese and carbon-supported silver catalysts, two carbon-supported materials are mixed by ball milling to obtain electrode materials. The preparation method is simple, but the ball milling of the two electrocatalysts mixes the distribution of the catalysts, resulting in insignificant catalytic effects.

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