Lithium-aluminum alloy, and production method and use thereof

Abstract

The invention relates to lithium-aluminum alloy, and a production method and use thereof, which belong to the technical field of a secondary battery negative material. The lithium-aluminum alloy has a longer charging-discharging cycling life. The lithium-aluminum alloy consists of the following components according to weight percent: 0.1 to 4.0 percent of aluminum, and the balance of lithium and unavoidable impurities. By adding the aluminum in specific content to the lithium, the performance of the pure metal lithium is modified, and not only can the advantages of the lithium capacity be maintained, but also a dendritic crystal inhibition effect can be improved. A single phase is used in the charging and discharging processes, the phase change can be avoided, and thus the charging-discharging cycling life of the lithium-aluminum alloy can be prolonged.

Description

technical field [0001] The invention relates to a lithium aluminum alloy and its production method and use, and belongs to the technical field of negative electrode materials for secondary batteries. Background technique [0002] Lithium is a silver-white metal with light texture, good ductility, strong electrical conductivity, quite active electrochemical properties, and strong reducibility. Its electrochemical equivalent is very small, 0.259g / Ah, and the theoretical ratio of lithium electrodes is The capacity reaches 3860Ah / kg, far exceeding 820Ah / kg of zinc, 260Ah / kg of lead and 481Ah / kg of cadmium. At the same time, the exchange current density of the lithium electrode is relatively large, and only a small polarization occurs in the electrode reaction. [0003] However, the metal lithium electrode used as the negative electrode of the secondary lithium battery will have great defects. The main defects are as follows: metal lithium batteries composed of metal lithium neg...

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Problems solved by technology

[0003] However, the metal lithium electrode used as the negative electrode of the secondary lithium battery will have great defects. The main defects are as follows: metal lithium batteries composed of metal lithium negative electrodes and ordinary organic electrolytes have problems such as low cycle efficiency and poor safety. Especially safety issues, when the battery is short-circuited, overheated, overcharged or overdischarged, the thermal runaway of the system may occur, and even cause an explosion

This poses many insurmountable problems for the commercialization of lithium metal batteries

But fundamentally speaking, the use of metal lithium as the negative electrode of secondary batteries has the following main problems: (1) the low charge-discharge cycle efficiency and the continuous increase of interface impedance caused by complex interfacial reactions; (2) "dendrite " and "dead lithium", resulting in safety issues and loss of electrode active materials

However, the lithium aluminum alloy prepared by the above method contains 18-24% of lithium (weight percentage), and the content of non-lithium alloy components is very high, which increases the electrode reaction potential of the lithium metal negative electrode and reduces the mass specific energy of the lithium negative electrode.

Moreover, during the charging and discharging process of the battery, the negative electrode material will inevitably undergo a phase change, resulting in a huge change in volume, resulting in rapid pulverization of the material and greatly reducing the cycle life.

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