High-temperature high-cycle negative electrode active material and preparation method thereof and nickel-metal hydride battery

Abstract

The invention relates to the field of nickel-metal hydride batteries, and discloses a high-temperature high-cycle negative electrode active material and a preparation method thereof and a nickel-metalhydride battery. The high-temperature high-cycle negative electrode active material comprises hydrogen storage alloy powder, the hydrogen storage alloy powder comprises a plurality of hydrogen storage alloy particles, the hydrogen storage alloy particles have a composition as shown in a general formula R1-aMgaYbNic-d-eAldTe which is described in the specification, wherein R comprises at least oneof La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ca, Sr, Sc, Ti, Zr and Hf, T comprises at least one of Mn, Co, V, Nb, Ta, Cr, Mo, Fe, Ga, Zn, Sn, In, Cu, Si, P and B, 0<a<=0.2, 0<b<=0.2, 3<= c<=4, 0<d<=0.50, and 0<e<=1. Therefore, the capacity of the battery is improved, the long-term charge-discharge performance of the battery in a high-temperature environment of 55 DEG C or aboveis improved, and the cycle service life of the battery is prolonged.

Description

technical field [0001] The invention relates to the field of nickel-hydrogen batteries, in particular to a high-temperature and high-cycle negative electrode active material, a preparation method thereof, and a nickel-hydrogen battery. Background technique [0002] As a backup power source, nickel-metal hydride battery is composed of hydrogen ions and metal nickel. It has 30% more power reserve than nickel-cadmium batteries, is lighter than nickel-cadmium batteries, has a longer service life, and has no pollution to the environment. It is environmentally friendly, With the advantages of long life and mature technology, it is used more and more, and its use temperature is also wider and wider. The current application environment temperature of high-temperature Ni-MH batteries is 50°C, which can no longer meet the growing new demands of the market. For example, the application temperature should be increased to above 55°C, and the service life needs to be maintained for more t...

AI Technical Summary

Problems solved by technology

This LaNi 5 Type hydrogen storage alloys have small capacity, poor long-term charge and discharge performance in a high temperature environment above 55°C, and short cycle life

[0004] In addition, during the charging and discharging process of the battery, due to the local severe polarization or overcharging of the positive electrode, the positive electrode reaches the oxygen evolution potential, thereby generating oxygen, which reaches the negative electrode through the diaphragm, and a part of the oxygen recombines at the negative electrode to form water, and there is always A part of oxygen oxidizes the hydrogen storage alloy because it cannot be recombined. After the surface of the hydrogen storage alloy powder is oxidized, the electrical contact and electrochemical activity of the powder decrease. As the temperature gradually increases, this oxidation phenomenon will become more and more serious. It is the main reason for the rapid loss of battery capacity during high temperature cycling.

In order to prevent the oxidation of the negative electrode, people coat metal nickel or metal copper on the surface of the hydrogen storage alloy powder, but this reduces the capacity density of the hydrogen storage alloy powder, reduces the effective capacity of the battery, and due to the surface of the hydrogen storage alloy powder Insufficient bonding of nickel or metallic copper cladding, resulting in poor effectiveness in preventing negative electrode oxidation

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