废旧锂离子电池回收制备MnO_(2)及其储锌性能

Zinc storage properties of MnO_(2) recovered from spent lithium-ion batteries

随着锂离子电池产业的快速发展,退役锂离子电池的回收利用问题已成为工业和学术界关注的热点。前人对废旧锂离子电池中有价值资源的回收做了大量研究,但将回收的锂离子电池材料直接转化为新型储能体系电极材料的研究鲜有报道。为实现退役电池的资源化再利用,可通过简单的H_(2)SO_(4)浸渍法,将废旧锂离子电池中锰酸锂(LiMn_(2)O_(4))材料转化为MnO_(2),并用做水系锌离子电池正极材料。通过XRD、XPS、BET、SEM、CV、TEM、EIS以及电化学性能测试等表征方法,探究酸浸渍条件如温度、时间等对所制备MnO_(2)形貌、结构和电化学性能的影响规律。结果表明:LiMn2O4材料经酸浸渍会发生歧化反应,使Li^(+)和部分Mn^(2+)从晶格中溶出,而浸渍温度对离子的溶出速度有显著影响。室温下,LiMn_(2)O_(4)晶格中离子的溶出速度较慢,可获得与其晶体结构相近的λ-MnO_(2)材料;而水热条件下,高反应温度会加剧晶格中原子的振动,加快离子溶出速度,形成晶体结构更紧密且热力学更稳定的γ-MnO_(2)和β-MnO_(2)。电化学性能测试结果显示,具有纳米棒状形貌和较大比表面积的γ-MnO_(2)材料,表现出较高的放电比容量和最优的循环稳定性,在0.3和3.0 A/g电流密度下,其放电比容量分别为273.3和127.2 mAh/g。在3.0 A/g电流密度下,γ-MnO_(2)材料经200、500和1 000圈循环后,其容量保持率高达77.1%、65.7%和43.9%。此外,通过ex-XRD表征研究发现,该Zn//MnO2电池的电化学储能机理遵循H^(+)/Zn^(2+)共插入/脱出机制。

With the rapid growth of the lithium-ion batteries,searching effective strategies for recycling decommissioned LIBs has become a hot topic in the fields of industry and academia.Previous studies have extensively investigated the recovery of valuable resources from waste lithium-ion batteries,but the study on directly converting waste lithium-ion battery materials into electrode materials of new energy storage system is relatively few.To achieve the resource reuse of retired batteries,a simple H 2 SO 4 impregnation method could be used to convert lithium manganese oxide(LiMn_(2)O_(4))material from waste lithium-ion batteries into MnO 2.Then the prepared MnO_(2)was used as the cathode material for aqueous zinc ion batteries.The effects of acid impregnation temperature and time on the morphology,structure,and electrochemical performance of the prepared MnO_(2)were investigated through the characterization technologies of XRD,XPS,BET,SEM,CV,TEM,EIS,and electrochemical performance test.The results indicate that LiMn_(2)O_(4) material could undergo dismutation reaction during acid impregnation process,and the Li+and some Mn 2+would dissolve from LiMn_(2)O_(4) lattice.It is found that the impregnation temperature has a significant impact on the ion dissolution rate.At room temperature,the dissolution rate of ions in LiMn_(2)O_(4) lattice is slow,andλ-MnO_(2)material with similar crystal structure with that of LiMn_(2)O_(4) is obtained.While under hydrothermal condition,the relatively high reaction temperature would intensify the vibration of atoms in lattice,and accelerate the rate of ion dissolution.Then more compact and thermodynamically stable crystal structures ofγ-MnO_(2)andβ-MnO_(2)are obtained.The electrochemical performance test results show thatγ-MnO_(2)material with a nanorod-like morphology and a large specific surface area exhibits high discharge capacities of 273.3 and 127.2 mAh/g at the current densities of 0.3 and 3.0 A/g,respectively.It also displays the optimal cyclic stability and the corresponding capacity retentions are 77.1%,65.7%,and 43.9%after 200,500,and 1000 cycles at the current density of 3.0 A/g.In addition,the electrochemical mechanism study by ex-XRD technology shows that the energy storage mechanism of this Zn//MnO_(2)cell follows a H+/Zn^(2+)co-insertion/extraction mechanism.