Magnesium-doped positive electrode material for magnesium ion battery and preparation method thereof

Abstract

The invention relates to a magnesium-doped positive electrode material for a magnesium ion battery and a preparation method thereof, and belongs to positive electrode materials for rechargeable batteries in energy materials. The molecular formula of the positive electrode material is Mg(1-x)AxNiSiO4, wherein A is one of doping elements Ca, Sr and Ba, and x is equal to 0.001 to 0.08. The preparation method comprises the following steps: accurately weighing a magnesium source compound, a doping element compound and a nickel source compound according to the atom mole ratio of Mg, A to Ai being (1-x): x: 1, adding an appropriate amount of deionized water, ball-milling and mixing uniformly, drying after taking out the mixture, and firing to obtain solid powder. Tetraethyl orthosilicate is weighed in proportion according to the atom mole ratio of Ni to Si being 1: 1, the solid powder, the tetraethyl orthosilicate and an appropriate amount of citric acid are sufficiently mixed in an absolute ethyl alcohol solvent, and the mixture is put in a stainless steel tank to obtain a gel substance. Then, mixed ball-milling is carried out with a carbon source compound, and sintering is carried out in an inert atmosphere for a few hours, so that the carbon coated positive electrode material Mg(1-x)AxNiSiO4 for the magnesium ion battery is obtained.

Description

Technical field [0001] The invention belongs to the field of preparation of cathode materials for magnesium ion batteries, and particularly relates to a magnesium site-doped nickel magnesium silicate anode material Mg for magnesium ion batteries (1-x) A x NiSiO 4 And its preparation method. Background technique [0002] Lithium-ion batteries are currently the most widely used secondary batteries. However, the global lithium resources are not rich. Lithium-ion batteries have greater safety hazards in the application process, especially when used as power batteries, forcing people to develop lithium-ion batteries At the same time, strive to find other secondary battery systems. In recent years, certain progress has been made in the research of magnesium-ion batteries. The diagonal positions of magnesium and lithium in the periodic table, according to the law of diagonals, have many similarities in their chemical properties. Magnesium reserves are very abundant on the earth. my cou...

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Problems solved by technology

[0003] There are two main obstacles to the technological development of magnesium-ion batteries: first, in the process of charging and discharging, a surface passivation film will be formed on the surface of the electrode material. Unlike lithium, the surface film of lithium can conduct lithium ions, while The passivation film formed on the surface of the magnesium electrode is difficult to conduct divalent magnesium ions, so that the deposition and dissolution of magnesium can proceed smoothly; Intercalation, the movement in the intercalation material is difficult, and there are few matrix materials for the rapid intercalation of magnesium ions, so the selection of positive electrode materials has become an important issue. Finding suitable positive electrode materials is the key to the research of magnesium ion batteries

[0004] People have carried out research on the positive electrode materials of magnesium ion batteries, and most of the positive electrode materials of magnesium ion batteries are inorganic transition metal compounds, concentrated as oxides (such as V 2 o 5 ), sulfide (such as the sulfide Mo of the Chevrel phase 6 S 8 ), phosphate polyanions (such as Mg 0.5+y (Fe y Ti 1-y ) 2 (PO 4 ) 3 ), etc., the main problems of these materials are: poor compatibility between materials and electrolyte, slow kinetics of magnesium intercalation, low intercalation capacity, large charge-discharge voltage difference, and poor cycle performance

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