Self-discharge screening method for lithium ion phosphate battery

A technology of a lithium iron phosphate battery and a screening method, which is applied in the field of lithium ion batteries, can solve problems such as the inability to properly screen lithium iron phosphate batteries with large self-discharge, and achieve the effects of high reliability, improved consistency and simple operation.

Active Publication Date: 2011-07-06
HEFEI GUOXUAN HIGH TECH POWER ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The object of the present invention is to overcome the shortcoming of using the discharge state to shelve the lithium iron phosphate battery with large self-di

Method used

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  • Self-discharge screening method for lithium ion phosphate battery
  • Self-discharge screening method for lithium ion phosphate battery
  • Self-discharge screening method for lithium ion phosphate battery

Examples

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Embodiment 1

[0017] Example 1 In the composite positive electrode containing lithium iron phosphate, a layered lithium nickel cobalt manganese oxide LiNi with a mass fraction of 3 wt% of lithium iron phosphate is added 0.4 co 0.2 mn 0.4 o 2 , with graphite as the negative electrode, assembled into a lithium iron phosphate battery. The battery discharge curve is as figure 2. Charge the battery with a constant current of 0.33C to 3.65V, and then charge it at a constant voltage of 3.65V until the current reaches the cut-off current of 0.02C, then stop charging; measure and record the voltage, and leave the battery at 25±2°C for 10 day, measure and record the voltage again; calculate the voltage difference and the voltage change value per unit time (K value), and determine the voltage difference of the self-discharging large battery for 10 days or the critical value of the voltage change per unit time is 40mV or 4mV / d , judging that the voltage difference or the voltage change per unit ti...

Embodiment 2

[0020] Example 2 In the composite positive electrode containing lithium iron phosphate, a spinel-like lithium manganese oxide LiMn with a mass fraction of 5 wt% of lithium iron phosphate is added 2 o 4 , with graphite as the negative electrode, assembled into a lithium iron phosphate battery. The battery discharge curve is as image 3. Charge the battery with a constant current of 0.33C to 3.8V, and then charge it at a constant voltage of 3.8V until the current reaches the cut-off current of 0.02C, then stop charging; measure and record the voltage, and leave the battery at 25±2°C for 10 day, measure and record the voltage again; calculate the voltage difference and the voltage change value (K value) per unit time, and determine the voltage difference of the self-discharging large battery for 10 days or the critical value of the voltage change per unit time is 40mV or 4mV / d, judging that the voltage difference or the voltage change per unit time is greater than the critical...

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Abstract

The invention discloses a self-discharge screening method for a lithium ion phosphate battery, belongs to the technical field of lithium ion batteries, and aims to provide a method for effectively screening the lithium ion phosphate battery with high self-discharge rate by using shelving in a charging state. According to the technical key points, the method comprises the following steps of: adding laminar lithium nickel cobalt manganese oxide or spinel lithium nickel manganese oxide which comprises 0.5 to 5 weight percent of lithium ion phosphate and has high voltage platform into a lithium ion phosphate-containing compound positive electrode; assembling the lithium ion phosphate battery by taking graphite as a negative electrode; fully charging the battery and then shelving the battery at an ambient temperature of between 20 and 45 DEG C; recording voltages before and after the shelf and shelf time; calculating the voltage difference before and after the shelf or a voltage variation value in unit time; and determining a critical value of the voltage difference of the batteries with the high self-discharge rate which are shelved in the same period or voltage variation in the unit time, and determining that the self-discharge rate of the battery of which the voltage difference or the voltage variation value in the unit time is greater than the critical value is high.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a self-discharge screening method for lithium iron phosphate batteries. Background technique [0002] With the depletion of oil resources, it has become an inevitable trend to develop electric vehicles that use electricity as a power source to replace the current fuel vehicles, and the importance of power batteries, the core component of electric vehicles, is particularly prominent. [0003] Due to its high energy density, low self-discharge, and long service life, lithium-ion power batteries have become the focus of research and development of power batteries for electric vehicles. At present, there are two main types of power batteries used in electric vehicles: one is lithium manganese oxide power battery, and the other is lithium iron phosphate power battery. Lithium iron phosphate batteries occupy the main market of electric vehicle power batteries due to their superior...

Claims

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Application Information

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IPC IPC(8): H01M10/058B07C5/344
CPCY02E60/12Y02E60/10Y02P70/50
Inventor 贺狄龙张良新饶晓东郭小烛
Owner HEFEI GUOXUAN HIGH TECH POWER ENERGY
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