Ultrafine manganese hexacyanoferrate with low defects regulated by potassium polyacrylate for high-performance aqueous Zn-ion batteries

• Published in: Journal of energy storage 2023-11, Vol.72, p.108535, Article 108535
• Main Authors: Liu, Bingqiu, Zhao, Ruiyi, Zhang, Qi, Ali, Usman, Li, Yiqian, Hao, Yuehan, Jia, Hongfeng, Li, Yanxin, Zeng, Guowei, Sun, Maoyu, Fu, Lihua, Zhang, Yu, Sun, Hang, Zhang, Lingyu, Li, Lu, Wang, Chungang
• Format: Article
• Language: English
• Subjects: [Fe(CN)6] vacancies and water; Aqueous Zn-ion batteries; Cathode; Surfactants of potassium polyacrylate; Ultrafine Prussian blue analogues
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2023.108535

Manganese hexacyanoferrate (MnHCF) is an ideal candidate for aqueous Zn-ion batteries (AZIBs) because of their high capacity and high operating voltage. Adding surfactant during the preparation process is an effective way to reduce the [Fe(CN)6] vacancies and water, leading to a stable structure and excellent electrochemical performance. However, the size of MnHCF becomes large (> 100 nm) after adding surfactant, resulting in the sluggish kinetics of Zn-ion transport and low utilization rate of active materials. Herein, ultrafine MnHCF (15 nm) (MnHCF-15) with few vacancies and low water content has been fabricated by introducing a typical surfactant of potassium polyacrylate (PAAK). Moreover, PAA-K can also precisely regulate the size of MnHCF, which exhibit a series of nano-sizes of 15, 50, 80, and 120 nm. The MnHCF-15 cathode exhibited a high capacity of 139.2 mA h g−1 at 0.05 A g−1 with a high operating voltage of 1.75 V. The excellent cycling stability of 92.5 %, 91.9 %, and 84.5 % capacity retention at 0.1, 0.2, and 0.5 A g−1 for 1000 cycles were also achieved because of the ultrafine size and the low defect of MnHCF-15. Ex-situ XRD and XPS were carried out to probe Zn-ion storage mechanism, indicating a reversible electrochemical reaction of the MnHCF-15 cathode. Impressively, the soft-packed AZIBs with high electrochemical performance highly reveal the practical application of the MnHCF-15. The results of this work offer a promising cathode material and lead to a new understanding on the nano-size effect of PBAs in AZIBs. Uniform ultrafine manganese hexacyanoferrate (MnHCF) is synthesized by adding a novel surfactant of potassium polyacrylate (PAAK), which shows excellent electrochemical performance as cathode materials for aqueous zinc-ion batteries. [Display omitted] •Uniform ultrafine manganese hexacyanoferrate (15 nm) nanocubes were fabricated by adding a novel surfactant of potassium polyacrylate (PAAK).•The PAA-K can also effectively decrease the coordinated water molecules and [Fe(CN)6] vacancies.•The ultrafine manganese hexacyanoferrate exhibits outstanding zinc ion-storage performance with high capacity, high operating voltage and long cycle life.