{"title":"Enhancing the cycling performance of manganese oxides through pre-sodiation for aqueous Zn-ion batteries†","authors":"Anjeline Williams and Prasant Kumar Nayak","doi":"10.1039/D4MA00824C","DOIUrl":null,"url":null,"abstract":"<p >Although Li-ion batteries have dominated the portable electronics market due to their high energy density and long cycle-life, it is essential to find alternative energy storage devices that can be cost-effective and environmentally friendly because of the low abundance and high cost of Li. In this regard, aqueous Zn-ion batteries are promising, because of their high abundance, low cost, high gravimetric capacity of the Zn anode and the environmental friendliness of aqueous electrolytes compared to flammable and costly organic electrolytes. Manganese oxides are the preferred cathode materials for aqueous Zn-ion batteries because of their specific capacity above 200 mA h g<small><sup>−1</sup></small>, low cost and environmental friendliness. However, they suffer from capacity fading due to manganese dissolution and structural transformation upon cycling. In this study, pre-sodiated manganese oxide Na<small><sub>0.6</sub></small>MnO<small><sub>2</sub></small> is synthesized by a hydrothermal method, followed by annealing at 900 °C, and its performance was tested for Zn-ion batteries by means of cyclic voltammetry, galvanostatic charge–discharge cycling and electrochemical impedance spectroscopy. Interestingly, Na<small><sub>0.6</sub></small>MnO<small><sub>2</sub></small> delivers an initial specific capacity of 165 mA h g<small><sup>−1</sup></small>, showing approximately 77% capacity retention over 150 cycles when cycled at 0.2 A g<small><sup>−1</sup></small> in the voltage domain of 1.0–2.0 V <em>vs.</em> Zn in 1.0 M ZnSO<small><sub>4</sub></small> + 0.1 M MnSO<small><sub>4</sub></small>. On the other hand, Mn<small><sub>2</sub></small>O<small><sub>3</sub></small> (without pre-sodiation) exhibits a high specific capacity above 200 mA h g<small><sup>−1</sup></small>; however, it undergoes severe capacity fading and retains only 26% capacity after 150 cycles. The <em>ex situ</em> XRD analysis shows the formation of a major spinel ZnMn<small><sub>2</sub></small>O<small><sub>4</sub></small> phase along with a ZnMn<small><sub>3</sub></small>O<small><sub>7</sub></small> phase, thus confirming the intercalation of the zinc-ion during the discharge process. Thus, this study enlightens the importance of pre-sodiation of manganese oxides in aqueous Zn-ion batteries for maintaining a stable specific capacity upon prolonged cycling.</p>","PeriodicalId":18242,"journal":{"name":"Materials Advances","volume":" 24","pages":" 9699-9715"},"PeriodicalIF":5.2000,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ma/d4ma00824c?page=search","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials Advances","FirstCategoryId":"1085","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/ma/d4ma00824c","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Although Li-ion batteries have dominated the portable electronics market due to their high energy density and long cycle-life, it is essential to find alternative energy storage devices that can be cost-effective and environmentally friendly because of the low abundance and high cost of Li. In this regard, aqueous Zn-ion batteries are promising, because of their high abundance, low cost, high gravimetric capacity of the Zn anode and the environmental friendliness of aqueous electrolytes compared to flammable and costly organic electrolytes. Manganese oxides are the preferred cathode materials for aqueous Zn-ion batteries because of their specific capacity above 200 mA h g−1, low cost and environmental friendliness. However, they suffer from capacity fading due to manganese dissolution and structural transformation upon cycling. In this study, pre-sodiated manganese oxide Na0.6MnO2 is synthesized by a hydrothermal method, followed by annealing at 900 °C, and its performance was tested for Zn-ion batteries by means of cyclic voltammetry, galvanostatic charge–discharge cycling and electrochemical impedance spectroscopy. Interestingly, Na0.6MnO2 delivers an initial specific capacity of 165 mA h g−1, showing approximately 77% capacity retention over 150 cycles when cycled at 0.2 A g−1 in the voltage domain of 1.0–2.0 V vs. Zn in 1.0 M ZnSO4 + 0.1 M MnSO4. On the other hand, Mn2O3 (without pre-sodiation) exhibits a high specific capacity above 200 mA h g−1; however, it undergoes severe capacity fading and retains only 26% capacity after 150 cycles. The ex situ XRD analysis shows the formation of a major spinel ZnMn2O4 phase along with a ZnMn3O7 phase, thus confirming the intercalation of the zinc-ion during the discharge process. Thus, this study enlightens the importance of pre-sodiation of manganese oxides in aqueous Zn-ion batteries for maintaining a stable specific capacity upon prolonged cycling.
尽管锂离子电池因其高能量密度和长循环寿命而主导了便携式电子市场,但由于锂的丰度低且成本高,因此找到具有成本效益和环保的替代能源存储设备至关重要。在这方面,水性锌离子电池很有前景,因为它们丰度高、成本低、锌阳极的重量容量大,而且与易燃和昂贵的有机电解质相比,水性电解质对环境友好。锰氧化物具有比容量大于200ma h g−1、成本低、环境友好等优点,是制备水性锌离子电池的首选正极材料。但在循环过程中,由于锰的溶解和结构的转变,它们的容量会下降。本研究采用水热法合成了预硫化氧化锰Na0.6MnO2,并在900℃下退火,采用循环伏安法、恒流充放电循环法和电化学阻抗谱法对其在锌离子电池中的性能进行了测试。有趣的是,Na0.6MnO2提供了165 mA h g−1的初始比容量,在1.0 - 2.0 V电压域中以0.2 A g−1循环时,与在1.0 M ZnSO4 + 0.1 M MnSO4电压域中的Zn相比,在150次循环中显示出约77%的容量保持率。另一方面,未经预酸化处理的Mn2O3表现出200 mA h g−1以上的高比容量;然而,它经历了严重的容量衰退,在150次循环后仅保留26%的容量。非原位XRD分析表明,在放电过程中形成了一个主尖晶石相ZnMn2O4和一个ZnMn3O7相,从而证实了锌离子的插层作用。因此,本研究启发了锰氧化物在水性锌离子电池中预酸化对于在长时间循环下保持稳定比容量的重要性。