废旧锂离子电池负极梯级提锂

Cascade Extraction of Lithium in Anode of Waste Lithium-Ion Battery

废旧锂离子电池保持容量的不同直接影响其回收价值,使用电池循环测试系统,按保持容量不同对废旧锂离子电池进行分类。在30℃条件下,用硫酸配合超声预处理方式,对分类后的负极材料进行浸出回收实验,并利用X射线光电子能谱(XPS)、X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、电感耦合等离子光谱仪(ICP)和激光粒度分析仪对不同锂离子电池负极材料及浸出实验进行表征。结果显示,约有28%的废旧锂离子电池保持容量超过75%,电池循环性能良好且负极材料Li含量相对较低,适于电芯整体再利用;保持容量降低,电池循环性能衰减而负极Li含量逐渐升高;保持容量在25%~50%范围,电池循环性能迅速衰减而负极Li含量达到峰值,适于负极Li提取。保持容量较高时,负极Li元素多以水溶性化合物的形式存在于表面SEI膜(固体电解质界面膜)中,可由常温水浸出达到84.52%回收率。随保持容量的降低,Li更多以LiF等非水溶性化合物的形式存在,且有更多的Li进入石墨内部,水浸或直接酸浸出的回收效果不佳,经超声预处理后由硫酸浸出可达98%回收率。

The capacity of the waste lithium-ion battery directly affects its recycling value.Use the battery test system to classify waste lithium-ion batteries according to the different retention capacity.Ultrasonic pretreatment and sulfuric leaching experiments of the classified anode materials were performed at 30 ℃.X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectroscopy(EDS),inductively coupled plasma(ICP)atomic emission spectroscopy and laser particle size analyzer were used to characterize the anode materials and leaching process of different lithium-ion batteries.The results showed that about 28% of the used lithium-ion batteries maintained a capacity of more than 75%,the battery cycle performance was good and the Li content of the anode material was relatively low,which was suitable for the overall reuse.With the decrease of the holding capacity,the battery cycle performance was attenuated and the Li content of the anode was gradually increased.In the capacity range of 25%~50%,the battery cycle performance was rapidly attenuated and the anode Li content peaked,which was suitable for the Li extraction.When the holding capacity was high,the anode Li was mostly water-soluble components present in the surface SEI(solid electrolyte interphase)film,which could be recovered by direct water leaching to reach 84.52% recovery.As the retention capacity decreased,more Li element was in the form of non-water-soluble components such as LiF,and relatively more Li entered the interior of the graphite.The recovery rate of water leaching or direct acid leaching was not appropriate.After ultrasonic pretreatment,the sulfuric acid leaching could reach 98% recovery.