Method for preparing modified spinelle manganic acid lithium material and lithium secondary battery

A spinel lithium manganate, lithium secondary battery technology, applied in the field of electrochemistry, can solve problems such as capacity decay, and achieve the effects of improving compatibility, easy industrialization, and low production cost

Active Publication Date: 2007-09-19
SHENZHEN BAK POWER BATTERY CO LTD
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Problems solved by technology

However, experiments have found that these methods have improved cycle performance during low-rate charge and discharge at room temperature, ...
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Abstract

The invention discloses a modified spinel lithium manganate material used in anode material of lithium secondary battery, the lithium manganate is a kind of doped lithium manganate LiaMn2-bXbO4 with other metallic element X, wherein X is at least one element of chroumium, gallium, magnesium, titanium, cuprum, zincum, 0.97 <= a <= 1.07, 0 <= b <= 0.1; and the surface of the said doped lithium manganate LiaMn2-bXbO4 is provided with a coat which contains at least one kind of boron-lithium composite oxides, cobalt-lithium composite oxides, vanadium-lithium composite oxides or carbon layer. The invention also discloses a preparing method for the said material and the lithium secondary battery using the said material as anode material. The invention provided modified spinel lithium manganate material has relative good high rate deep discharge capacity in normal temperature or high temperature, in mean time, the preparing method is easy for control and operation and industrialisation, and production cost thereof is low.

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  • Method for preparing modified spinelle manganic acid lithium material and lithium secondary battery
  • Method for preparing modified spinelle manganic acid lithium material and lithium secondary battery
  • Method for preparing modified spinelle manganic acid lithium material and lithium secondary battery

Examples

  • Experimental program(4)
  • Comparison scheme(2)

Example Embodiment

[0035] Example 1
[0036] Weigh LiOH·H 2 0 1Kg, and get zirconia balls by mass ratio 1.5: 1 (material weight/ball weight) and add them to the ball mill and dry them for later use after ball milling for 2h, weigh LiOH H in molar ratio 1: 1.96: 0.02: 0.02 2 O (ball milled), electrolytic manganese dioxide (EMD), titanium dioxide (TiO 2 ) and copper oxide (CuO) into the ball mill, add about 1 times the weight of zirconia balls for ball milling for 4h, then calcinate at 500°C for 5h, then continue to calcine at 800°C for 10h, naturally cool to room temperature, take out for grinding, sieve ( 300 mesh or so) to obtain preliminary material A1. Li by mole ratio 2 O-2B 2 O 3 / Preliminary material = 0.5% Weigh out LiOH·H 2 O and H 3 BO 3 Put it in a beaker, and add about 20 times the mass of methanol to dissolve it to obtain LiOH·H 2 O-H 3 BO 3 /Methanol coating solution B1. The amount of methanol added is generally based on the principle of saving and ensuring LiOH·H 2 O and H 3 BO 3 sufficient dispersion to determine. Under constant stirring (stirring speed about 300-500 rpm), the prepared preliminary material A1 was added to the coating solution B1, heated for about 4 hours while stirring, and then placed in an oven at 150°C for 12 hours. The resulting powder is calcined at 600° C. for 6 hours, cooled to room temperature naturally, ground, and sieved (about 300 mesh).
[0037] In order to detect the morphology of the materials prepared in this example, the materials prepared in this example were taken for XRD test, and the results are shown in FIG. 1 . It can be seen from Figure 1 that the XRD peaks before and after material doping and coating are almost the same, which is a spinel structure. There are no new impurity peaks in the spectrum, indicating that the doped metal ions exist in the material unit cell, and the surface coating Li 2 O-2B 2 O 3 Exist in an amorphous glass state. In order to detect the electrochemical properties of the materials prepared in this example, 91 parts of the materials prepared in this example, 5 parts of the conductive agent, 4 parts of the binder polyvinylidene fluoride (PVDF) and an appropriate amount of N-methylpyrrolidone (NMP) were prepared. Slurry, coated on both sides of the aluminum foil to obtain a positive electrode, the surface density of the positive electrode is 38mg/cm 2 , according to the normal production process to assemble a battery with a model of 423048A, and test its charge-discharge, rate cycle performance, and high-temperature charge-discharge performance on the Xinwei battery tester. Its structure and electrochemical performance test results are shown in Figures 2-3. It can be seen from Figure 2 that when the material is discharged at a rate, the lithium ion deintercalation channel is very smooth (the middle part of each rate discharge curve is very parallel), so the material has good rate and cycle performance. For example, the capacity retention of charge and discharge at room temperature 3C, 5C, 7C, and 9C are 97.4%, 98.1%, 91.5% and 73.9% of the capacity at room temperature 1C, respectively, and the capacity retention rates for 200 cycles are 93.5%, 92.9%, 92.1% and 92.1%, respectively. 93.4%. The high temperature 55℃ 1C and 7C charge and discharge capacities are 97.8% and 96.2% of the normal temperature 1C charge and discharge capacities, respectively, and the capacity retention rates after 100 cycles under this condition are 88.9% and 91.7%, respectively. The material has a good high temperature depth discharge performance.

Example Embodiment

[0038] Example 2:
[0039] Weigh Li 2 CO 3 1Kg, and take zirconia balls in a mass ratio of 1.5:1 (material weight/ball weight) and add them to the ball mill for 2h and then dry them for later use. 2 CO 3 (Ball-milled), Electrolytic Manganese Dioxide (EMD), Chromium Oxide (Cr 2 O 3 ) and aluminum nitrate (Al(NO) 3 ) 3 ) into the ball mill, and add about 1 times the weight of zirconia balls for 4 hours, then calcined at 450 ° C for 8 hours, and then continued to sinter at 850 ° C for 8 hours, and then cooled to room temperature naturally, taken out, ground and sieved (about 300 mesh) to obtain a preliminary Material A1. According to the molar ratio C/preliminary material=0.6%, weigh an appropriate amount of polyvinyl alcohol PVA and place it in a beaker and add about 20 times of ethanol to dissolve to obtain PVA coating solution B1. The amount of ethanol added is also based on the principle of saving and ensuring the sufficient dispersion to determine. Under the condition of constant stirring (stirring speed is about 300-500rpm), the prepared preliminary material A1 was added to the coating solution B1, heated for about 4 hours while stirring, and then placed in an oven for 16 hours at 120°C. The resulting powder was calcined at 620° C. for 6 hours, cooled to room temperature naturally, ground, and sieved (about 300 mesh) to obtain modified spinel lithium manganate coated with carbon layer.
[0040] Using this material as the positive electrode active material, the electrochemical performance test results of the battery assembled in the manner of Example 1 are: the capacity retention of charge and discharge at room temperature 3C, 5C, 7C, and 9C is 92.6% and 91.3% of the capacity of 1C at room temperature, respectively. , 90.5% and 71.4%, and the capacity retention rates of 200 cycles were 92.9%, 90.1%, 91.4% and 90.8%, respectively. The charge-discharge capacities at high temperature 55°C at 1C and 7C are 96.9% and 92.2% of the charge-discharge capacities at room temperature at 1C, respectively, and the capacity retention rates after 100 cycles under these conditions are 90.1% and 87.9%, respectively.

Example Embodiment

[0041] Example 3
[0042] Weigh anhydrous LiNO 3 1Kg, and take zirconia balls in a mass ratio of 1.5:1 (material weight/ball weight), add them to the ball mill for 2h, and dry them for later use. Weigh LiNO in a molar ratio of 1.05:1.94:0.01:0.04. 3 (ball milled), electrolytic manganese dioxide (EMD), gallium oxide (Ga 2 O 3 ) and magnesium hydroxide (Mg(OH) 2 ) into the ball mill, and add about 1 times the weight of zirconia balls for 4 hours, then calcined at 600 °C for 4 hours, then continued to calcine at 800 °C for 14 hours, and then cooled to room temperature naturally, taken out for grinding and sieving (about 300 mesh) to obtain a preliminary Material A1. Lithium carbonate: cobalt tetroxide in molar ratio: preliminary material=3: 2: 100 Weigh lithium carbonate and cobalt tetroxide and place them in a beaker, and add about 20 times the mass of acetone to dissolve to obtain lithium carbonate and cobalt tetroxide mixed solution B1, the added acetone The amount is also determined according to the principle of saving and ensuring sufficient dispersion of lithium carbonate and cobalt tetroxide. Under the condition of constant stirring (stirring speed is about 300-500rpm), the prepared preliminary material A1 is added to the solution B1, heated for about 4 hours while stirring, and then placed in an oven to be dried at 100°C for 18 hours. The powder is calcined at 660° C. for 7 hours, cooled to room temperature naturally, ground, and sieved to obtain modified spinel lithium manganate coated with cobalt-lithium composite oxide.
[0043] Using this material as the positive electrode active material, the electrochemical performance test results of the battery assembled in the manner of Example 1 are: the capacity retention of charge and discharge at room temperature 3C, 5C, 7C, and 9C are respectively 93.5% and 93.3% of the capacity at room temperature 1C. , 90.7% and 76.7%, and the capacity retention rates for 200 cycles were 88.7%, 87.1%, 86.9% and 86.8%, respectively. The high temperature 55℃ 1C and 7C charge and discharge capacities are 98.6% and 87.1% of the normal temperature 1C charge and discharge capacities, respectively, and the capacity retention rates after 100 cycles under this condition are 91.6% and 87.8%, respectively.
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