Stable Quasi‐Solid‐State Aluminum Batteries

Abstract

nonflammable ionic liquid (IL) electrolytes. Thus, they have been considered as one of the candidates for next-generation batteries in large-scale energy storage. [2] Particularly, Al-graphite batteries with a chloroaluminate-based IL electrolyte are the most promising RAB systems due to their high stability, reliability, and low-cost advantages. [3] Nevertheless, the IL electrolytes with their high moisture sensitivity can cause several critical problems in Algraphite batteries, including undesirable volume expansion in the cell, decreased Coulombic efficiency, and irreversible capacity decay, which have limited their practical applications. [2b,c] In the ambient environment, chloroaluminate-based IL electrolytes are prone to absorb H 2 O, and would subsequently react with chloroaluminate-based anions to produce H 2 , Cl 2 , and HCl, which greatly impacts the battery stability (Figure 1a). [4] Meanwhile, the gas will change the geometry of electrode/ electrolyte interface and affect the mass transfer process, resulting in unbalanced energy storage and output. [5] More importantly, the degradation of the chloroaluminate-based IL will substantially undermine the active ions in the electrolytes, which leads to severe performance decay. [6] In the early attempts, the chloroaluminate-based IL was encapsulated in the polymeric frameworks, including polyacrylamide, poly-(3,4-ethylenedioxythiophene), and polyamide, for achieving gel electrolytes, where the IL provides active ions and polymers act as a protective framework from moisture. [4b,5-7] Although the air stability of IL-based gel electrolytes has been improved due to the shielding effect of polymer frameworks, they still have strong hygroscopic properties. The critical issues of gas production and activity loss have not been effectively addressed in the battery operation, because of very high content of IL (over 90%) and limited protection from the polymer frameworks. [4b] In comparison with liquid electrolytes, employment of a (quasi-) solid-state electrolyte could effectively enhance the stability of the IL-based electrolyte in air, thus substantially promoting the stability in practical RABs (Figure 1b). [8] Therefore, it is urgent to develop an appropriate framework that enables the chloroaluminate-based IL to be carried, for achieving quasi-solid-state electrolytes. As a typical high porosity framework material, metal-organic frameworks (MOFs) can store large amounts of large molecules and clusters via strong absorptive capability. [9] The stable frameworks in MOFs give rise to a confinement effect on the large molecules and clusters, and thus behave Nonaqueous rechargeable aluminum batteries (RABs) of low cost and high safety are promising for next-generation energy storage. With the presence of ionic liquid (IL) electrolytes, their high moisture sensitivity and poor stability would lead to critical issues in liquid RABs, including undesirable gas production, irreversible activity loss, and an unstable electrode interface, undermining the operation ...

Electrocatalysis for Continuous Multi‐Step Reactions in Quasi‐Solid‐State Electrolytes Towards High‐Energy and Long‐Life Aluminum–Sulfur Batteries

“…[25] A stable electrochemical window between 0 V and 2.47 V in linear sweep voltammetry (LSV) profiles is observed for the IL@MOF electrolyte (Figure S26), almost identical to that of pristine IL, because the MOF is stable against IL electrolyte under a wide potential range. [25] Furthermore, the interface features between IL@MOF electrolyte and Al metal were evaluated by the direct current Al plating/ stripping cycles, as shown in Figure 4c. A large polarization voltage of � 98 mV is observed in the initial cycle at 0.05 mA cm À 2 , indicating a high interfacial impedance between IL@MOF and Al metal.…”

Electrocatalysis for Continuous Multi‐Step Reactions in Quasi‐Solid‐State Electrolytes Towards High‐Energy and Long‐Life Aluminum–Sulfur Batteries

“…[25] A stable electrochemical window between 0 V and 2.47 V in linear sweep voltammetry (LSV) profiles is observed for the IL@MOF electrolyte (Figure S26), almost identical to that of pristine IL, because the MOF is stable against IL electrolyte under a wide potential range. [25] Furthermore, the interface features between electrolyte and Al metal were evaluated by the direct current Al plating/ stripping cycles, as shown in Figure 4c. A large polarization voltage of � 98 mV is observed in the initial cycle at 0.05 mA cm À 2 , indicating a high interfacial impedance between IL@MOF and Al metal.…”

“…Meanwhile, the IL@MOF electrolyte can achieve reversible deposition and stripping of aluminum with a small polarization potential (Figure S24), demonstrating free movement of chloroaluminate‐based ions (Al 2 Cl 7 − and AlCl 4 − ). The anion transference number ( t anion ) of the IL@MOF calculated from the DC polarization curve is 0.26 (Figure S25), which is slightly higher than that of pure IL, due to the confinement effect of MOF to EMIm + cations of large sizes [25] . A stable electrochemical window between 0 V and 2.47 V in linear sweep voltammetry (LSV) profiles is observed for the IL@MOF electrolyte (Figure S26), almost identical to that of pristine IL, because the MOF is stable against IL electrolyte under a wide potential range [25] .…”

“…The anion transference number ( t anion ) of the IL@MOF calculated from the DC polarization curve is 0.26 (Figure S25), which is slightly higher than that of pure IL, due to the confinement effect of MOF to EMIm + cations of large sizes [25] . A stable electrochemical window between 0 V and 2.47 V in linear sweep voltammetry (LSV) profiles is observed for the IL@MOF electrolyte (Figure S26), almost identical to that of pristine IL, because the MOF is stable against IL electrolyte under a wide potential range [25] . Furthermore, the interface features between IL@MOF electrolyte and Al metal were evaluated by the direct current Al plating/stripping cycles, as shown in Figure 4c.…”

Graphene-encapsulated selenium@polyaniline nanowires with three-dimensional hierarchical architecture for high-capacity aluminum–selenium batteries

“…Rechargeable aluminum batteries (RABs) have been considered as one of the potential candidates due to their great potential values with abundant natural resources, high-safety and reliability features. [1][2][3][4] At present, international research on RABs mainly focuses on the development of intercalation-type positive materials, such as graphite carbon materials, 5,6 transition metal oxides, [7][8][9] suldes, 10,11 etc. Among them, graphite carbon materials have the best cycle stability, but the discharge specic capacity was only 70 mA h g À1 , which was much lower than those of commercial lithium-ion batteries.…”