He Xinjun, Zhang Haozhe, Zhao Xingyu, Zhang Peng, Chen Minghua, Zheng Zhikun, Han Zhiji, Zhu Tingshun, Tong Yexiang, Lu Xihong
Key Laboratory of Engineering Dielectric and Applications (Ministry of Education) Harbin University of Science and Technology Harbin 150080 China.
MOE of the Key Laboratory of Bioinorganic and Synthetic Chemistry The Key Lab of Low-Carbon Chem & Energy Conservation of Guangdong Province School of Chemistry Sun Yat-Sen University Guangzhou 510275 P. R. China.
Adv Sci (Weinh). 2019 May 14;6(14):1900151. doi: 10.1002/advs.201900151. eCollection 2019 Jul 17.
Exploration of high-performance cathode materials for rechargeable aqueous Zn ion batteries (ZIBs) is highly desirable. The potential of molybdenum trioxide (MoO) in other electrochemical energy storage devices has been revealed but held understudied in ZIBs. Herein, a demonstration of orthorhombic MoO as an ultrahigh-capacity cathode material in ZIBs is presented. The energy storage mechanism of the MoO nanowires based on Zn intercalation/deintercalation and its electrochemical instability mechanism are particularly investigated and elucidated. The severe capacity decay of the MoO nanowires during charging/discharging cycles arises from the dissolution and the structural collapse of MoO in aqueous electrolyte. To this end, an effective strategy to stabilize MoO nanowires by using a quasi-solid-state poly(vinyl alcohol)(PVA)/ZnCl gel electrolyte to replace the aqueous electrolyte is developed. The capacity retention of the assembled ZIBs after 400 charge/discharge cycles at 6.0 A g is significantly boosted, from 27.1% (in aqueous electrolyte) to 70.4% (in gel electrolyte). More remarkably, the stabilized quasi-solid-state ZIBs achieve an attracting areal capacity of 2.65 mAh cm and a gravimetric capacity of 241.3 mAh g at 0.4 A g, outperforming most of recently reported ZIBs.
探索用于可充电水系锌离子电池（ZIBs）的高性能阴极材料非常必要。三氧化钼（MoO）在其他电化学储能装置中的潜力已被揭示，但在ZIBs中仍未得到充分研究。在此，展示了正交晶系MoO作为ZIBs中一种超高容量阴极材料。特别研究并阐明了基于锌嵌入/脱嵌的MoO纳米线的储能机制及其电化学不稳定性机制。MoO纳米线在充放电循环过程中的严重容量衰减源于其在水系电解质中的溶解和结构坍塌。为此，开发了一种通过使用准固态聚（乙烯醇）（PVA）/ZnCl凝胶电解质替代水系电解质来稳定MoO纳米线的有效策略。在6.0 A g下进行400次充放电循环后，组装的ZIBs的容量保持率显著提高，从（在水系电解质中）的27.1%提高到（在凝胶电解质中）的70.4%。更值得注意的是，稳定后的准固态ZIBs在0.4 A g下实现了2.65 mAh cm的诱人面积容量和241.3 mAh g的重量容量，优于最近报道的大多数ZIBs。
