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H2SO4浸渍法,将废旧锂离子电池中锰酸锂(LiMn2O4)材料转化为MnO2,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MnO2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Mn2+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,LiMn2O4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-MnO2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-MnO2和β-MnO2。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-MnO2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3.0A/g电流密度下,其放电比容量分别为273.3和127.2mAh/g。在3.0A/g电流密度下,γ-MnO2材料经200、500和1000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+/Zn2+共插入/脱出机制。

With the rapid growth of the lithium-ion batteries, searching effective strategies for recycling decommissioned LIBs has becomea hot topic in the fields of industry and academia. Previous studies have extensively investigated the recovery of valuable resources fromwaste lithium-ion batteries, but the study on directly converting waste lithium-ion battery materials into electrode materials of new energystorage system is relatively few. To achieve the resource reuse of retired batteries, a simple H2 SO4 impregnation method could be usedto convert lithium manganese oxide (LiMn2O4) material from waste lithium-ion batteries into MnO2. Then the prepared MnO2 was used asthe 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 MnO2 were investigated through the characterization technologies of XRD, XPS,BET, SEM, CV, TEM, EIS, and electrochemical performance test.The results indicate that LiMn2O4 material could undergo dismutationreaction during acid impregnation process, and the Li+ and some Mn2+ would dissolve from LiMn2O4 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 LiMn2O4 lattice isslow, and λ-MnO2 material with similar crystal structure with that of LiMn2O4 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 of γ-MnO2 and β-MnO2 are obtained. The electrochemical performance test resultsshow that γ-MnO2 material with a nanorod-like morphology and a large specific surface area exhibits high discharge capacities of 273.3and 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 1 000 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/ / MnO2 cell follows a H+ /Zn2+ co-insertion/ extraction mechanism.

0 引言

1 试验

   1.1 正极材料的回收

   1.2 MnO2的制备

   1.3 材料表征

   1.4 电化学性能测试

2 结果与讨论

   2.1 形貌和结构分析

   2.2 电化学性能测试

   2.3 反应动力学和机理研究

3 结论