Metal phosphorus trichalcogenides (MPX3) are of great interest since these layered materials exhibit wide applications in optical, electrical and magnetic fields. An effective chemical intercalation route for MPX3 which could regulate their physical properties, however, is still lacking. In this work, we show that the liquid ammonia method is an efficient route to co-intercalate alkali metals and NH3 molecules into the gaps in FePS3. After intercalation, the interlayer distance is significantly enlarged by ∼3 Å while the monoclinic lattice (C2/m space group) is still maintained. The structure refinement and EDS measurement suggest that intercalation does not induce any Fe vacancy, thus leading to electron transfer from the alkali metal to [FePS3] layers. Interestingly, magnetic susceptibility shows that the intrinsic anti-ferromagnetic transition in the FePS3 matrix is completely suppressed by this intercalation, whereas a spin-glass state is observed in A(NH3)xFePS3 (A = Li, K) in the lower temperature range (<50 K). The intercalation described in this work is reversible: the alkali metal can be easily de-intercalated using a two-step route and the anti-ferromagnetism reappears accordingly. Meanwhile, the liquid ammonia method is also shown to be efficient at intercalating other MPS3 materials (M = Mn, Co, Ni). Our work not only enriches the intercalation chemistry in the MPX3 system but also provides an excellent route to regulate the magnetic properties of these layered materials.
Leyuan Zhang,Liang Chen,Hao Luo,Xufeng Zhou,Zhaoping Liu
To develop high-power and high-energy batteries with a long life remains a great challenge, even combining the benefits of metal (fast kinetics and high capacity) and carbon materials (robust structure). Among them, Al-ion batteries based on aluminum anode and graphite carbon cathode have gained lots of interests as one of the most promising technologies. Here, it is demonstrated that the size of graphitic material in ab plane and c direction plays an important role in anion intercalation chemistry. Sharply decreasing the size of vertical dimension ( c direction) strongly facilitates the kinetics and charge transfer of anions (de)intercalation. On the other hand, increasing the size of horizontal dimension ( ab plane) contributes to improving the flexibility of graphitic materials, which results in raising the cycling stability. Meanwhile, chloroaluminate anions are reversibly intercalated into the interlayer of graphite materials, leading to the staging behaviors. In the end, an ultrafast Al-ion battery with exceptional long life is achieved based on large-sized few-layer graphene as a cathode and aluminum metal as an anode.
Bi Songshan,Wang Shuai,Yue Fang,Tie Zhiwei,Niu Zhiqiang
Aqueous rechargeable metal batteries are intrinsically safe due to the utilization of low-cost and non-flammable water-based electrolyte solutions. However, the discharge voltages of these electrochemical energy storage systems are often limited, thus, resulting in unsatisfactory energy density. Therefore, it is of paramount importance to investigate alternative aqueous metal battery systems to improve the discharge voltage. Herein, we report reversible manganese-ion intercalation chemistry in an aqueous electrolyte solution, where inorganic and organic compounds act as positive electrode active materials for Mn 2+ storage when coupled with a Mn/carbon composite negative electrode. In one case, the layered Mn 0.18 V 2 O 5 ·nH 2 O inorganic cathode demonstrates fast and reversible Mn 2+ insertion/extraction due to the large lattice spacing, thus, enabling adequate power performances and stable cycling behavior. In the other case, the tetrachloro-1,4-benzoquinone organic cathode molecules undergo enolization during charge/discharge processes, thus, contributing to achieving a stable cell discharge plateau at about 1.37 V. Interestingly, the low redox potential of the Mn/Mn 2+ redox couple vs. standard hydrogen electrode (i.e., −1.19 V) enables the production of aqueous manganese metal cells with operational voltages higher than their zinc metal counterparts.
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