Lithium embedding process of lithium supplement battery

Abstract

The invention discloses a lithium embedding method of a lithium supplement battery. The lithium embedding method comprises the following steps: charging the battery in a specific voltage range, then vacuumizing or standing, then carrying out secondary charging to fully supplement lithium, and finally vacuumizing and degassing. The invention provides a lithium embedding process of a lithium supplement battery, which can effectively avoid the influence of produced gas on the lithium supplement effect of the battery, and can greatly improve the performance of the battery.

Description

Technical Field

[0001] The invention relates to the technical field of new energy batteries, and in particular to a lithium insertion method for a lithium supplement battery. Background Art

[0002] When lithium-ion batteries are charged for the first time, a solid electrolyte interface film (SEI film) will be generated on the surface of the negative electrode, consuming a large amount of active lithium and affecting the battery capacity. There are currently two ideas for positive electrode lithium replenishment and negative electrode lithium replenishment. These two lithium replenishment technologies can effectively replenish the lost active lithium. Negative electrode lithium replenishment includes lithium powder replenishment and lithium foil replenishment. Since the lithium source used is relatively active, special equipment is usually required and it is produced in a harsh production environment. Compared with negative electrode lithium replenishment, positive electrode lithium replenishment usually uses materials such as Li2NiO2 and lithium-rich lithium ferrite to add to the positive electrode plate, which is more friendly to equipment and environmental requirements. However, some positive electrode lithium replenishment materials often produce a lot of gas during the lithium replenishment process, resulting in poor lithium replenishment effect.

[0003] The conventional lithium insertion process is to charge the lithium replenishment material at a specific voltage, so that the lithium replenishment material undergoes a decomposition reaction and lithium is inserted into the negative electrode material. During the lithium replenishment process, a negative pressure vacuum may be used. After the lithium replenishment is completed, degassing and packaging are performed. The use of this lithium insertion process is often accompanied by insufficient decomposition of the lithium replenishment material and uneven lithium insertion caused by gas, which leads to unsatisfactory lithium replenishment effect. Therefore, it is necessary to develop a better lithium insertion process to improve the lithium replenishment effect. Summary of the invention

[0004] The main technical problem solved by the present invention is the problem of poor lithium insertion in lithium-supplemented batteries. The present invention provides a lithium insertion process, which is simple in process, fully replenishes lithium, and can evenly embed lithium into the negative electrode material, effectively avoiding the influence of gas on the lithium-supplementing effect of the battery, and greatly improving the performance of the battery.

[0005] The present invention adopts the following technical scheme: the lithium insertion process is to charge the battery within a specific voltage range, then evacuate or stand it, then recharge it to fully replenish lithium to ensure that the lithium replenishing material reacts completely, and finally evacuate and degas.

[0006] Preferably, the lithium supplement material is one or more combinations of lithium supplement materials such as lithium nitride, lithium ferrite, lithium oxalate and lithium squarate that will generate gas during the lithium supplement process.

[0007] Preferably, the specific voltage range is the voltage range in which the lithium supplement material decomposes.

[0008] Preferably, the selected vacuuming step is to vacuumize the interior of the battery.

[0009] Preferably, the selected resting step is to place the battery at room temperature or high temperature.

[0010] Preferably, the selected secondary charging is to charge the lithium-supplemented battery for the second time after vacuuming or standing.

[0011] Advantages and beneficial effects of the present invention: The present invention provides a lithium insertion process for lithium supplementing materials, which can achieve full reaction of lithium supplementing materials in batteries, and the generated gas can be discharged from the battery, avoiding the adverse effect of gas on the lithium supplementing effect of the battery, and improving the performance of the battery. The present invention can be applied to the lithium insertion process of any gas-generating lithium supplementing material to improve the lithium insertion effect of the material. Specific implementation cases

[0012] Example 1 Lithium-rich lithium iron oxide is used as the lithium supplement material for lithium iron phosphate soft pack batteries. In the first cycle, a charging current of 0.05C is used, and the voltage range is 2.5-4.5V. After full charge, it is left to stand for 24 hours, and then charged to 4.5V using 0.05C again. Then it is vacuumed and vented for packaging. After disassembly, the battery pole piece has uniform color and no lithium precipitation, and the battery capacity is increased by 2.5%, and the cycle performance reaches more than 5000 times.

[0013] Example 2 Lithium-rich lithium iron oxide is used as the lithium supplement material for lithium iron phosphate square batteries. In the first cycle, a 0.05C charging current is used, the voltage range is 2.5-4.5V, and negative pressure vacuum is performed at the same time. After full charge, it is left to stand for 24 hours, and then charged again at 0.05C to 4.5V. Then vacuum degassing is performed. After disassembly, the battery pole piece has uniform color and no lithium precipitation, and the battery capacity is increased by 3%, and the battery cycle performance reaches more than 5,000 times.

[0014] Example 3 Squarate lithium is used as the lithium supplement material for lithium iron phosphate square batteries. In the first cycle, a 0.05C charging current is used, the voltage range is 2.5-4.4V, and negative pressure vacuum is performed at the same time. After full charge, it is left to stand for 24 hours, and then charged again with 0.05C to 4.4V. Then vacuum degassing is performed. After disassembly, the battery pole piece has uniform color and no lithium precipitation, and the battery capacity is increased by 4%, and the battery cycle performance reaches more than 6,000 times.

[0015] Example 4 Squarate lithium is used as the lithium supplement material for lithium iron phosphate soft pack batteries. In the first cycle, a 0.05C charging current is used, and the voltage range is 2.5-4.4V. After full charge, vacuum is evacuated, and then 0.05C is used to charge to 4.4V. Finally, vacuum is evacuated and degassed. After disassembly, the battery pole pieces are uniform in color and have no lithium deposition, and the battery capacity is increased by 5%, and the battery cycle performance reaches more than 6,000 times.

Claims

1. A lithium insertion method for a lithium supplement battery, characterized in that: The lithium insertion method comprises charging the lithium-supplemented battery within a specific voltage range, then vacuumizing the battery or leaving it to stand, recharging the battery to fully replenish lithium, and finally vacuumizing and degassing the battery.

2. The lithium supplement material according to claim 1, characterized in that: One or more combinations of lithium-replenishing materials such as lithium nitride, lithium-rich lithium ferrite, lithium oxalate and lithium squarate that will produce gas during the lithium replenishment process.

3. The specific voltage range according to claim 1, characterized in that: It is the voltage range in which lithium supplement materials decompose.

4. The vacuuming according to claim 1, characterized in that: Evacuate the inside of the battery.

5. The static setting according to claim 1, characterized in that: Let stand at room temperature or high temperature.

6. The secondary charger according to claim 4, characterized in that: Charge the lithium battery a second time after vacuuming or standing.