In situ Seamless Magnetic Measurements for Solid‐State Electrochemical Processes in Prussian Blue Analogues

Abstract

Seamless observation: Magnetic measurements in a solid‐state electrochemical environment have been developed and applied to a mixed‐valent chromium Prussian blue analogue (PBA) ferrimagnet. Battery cells containing PBA as a cathode active material were inserted into a SQUID and the PBA reduction during battery discharge was controlled. Magnetic changes were revealed that can be understood by the redox‐induced spin changes of the Cr ions.

Effect of Particle Size and Anion Vacancy on Electrochemical Potassium Ion Insertion into Potassium Manganese Hexacyanoferrates

“…Despite the 32 % Na/K vacancies, the sum of alkali metal content is still unusually high because the average oxidation state of Fe/Mn estimated from the charge balance was lower than +2 (Table 1). Although the high Na/K content is not fully understood, possible reasons are surface contamination of K compounds and the presence of Cl − and OH − in the anion vacancy, [13] which would increase alkali metal content. All refined structures were in agreement with the typical monoclinic structure for K‐rich KMnHCFs (space group of P 2 1 / n ; see details in Supporting Information, Tables S2–S4) [5b,c,14] .…”

The solid-state electrochemical reduction process of magnetite in Li batteries: in situ magnetic measurements toward electrochemical magnets

“…In addition, while keeping the redox potential constant, variabletemperature magnetic measurements are available down to 2 K. We have already applied this system to a mixed-valent chromium Prussian-blue ferrimagnet, Cr 2. 24 [Cr(CN) 6 ]$ Cl 0.13 (OH) 1.68 $5.25H 2 O (Cr-PBA), 11 with a ferrimagnetic transition temperature T N of 215 K, and found continuous changes in T N and the saturation magnetization, which were well understood by the redox/spin changes of Cr ions, though these magnetic changes occurred at low temperatures.…”

Magnetic Switching by the In Situ Electrochemical Control of Quasi‐Spin‐Peierls Singlet States in a Three‐Dimensional Spin Lattice Incorporating TTF‐TCNQ Salts

“…The in situ reversible magnetic phase switching between PM and FM phases was demonstrated through the rechargeability of the LIB system, for which a miniaturized LIB cell was inserted into a commercial superconducting quantum interference device (SQUID). This cell is hereafter called the in situ cell . Figure a displays the time dependence of the voltage for the discharge/charge cycles between 2.3 and 3.5 V versus Li/Li + (at 300 K), revealing the rechargeability of the LIB with the 1 ‐cathode.…”

“…This cell is hereafter called the in situ cell. [27,29] Figure 7a displays the time dependence of the voltage for the discharge/charge cycles between 2.3 and 3.5 Vv ersusL i/Li + (at 300 K), revealing the rechargeability of the LIB with the 1-cathode. The temperature dependence of the magnetization for each dischargedo rc harged state is shown in Figure 7b.I nt he discharged states (blue curves), the FM phases, T c of which are almostt he same values, appear repeatedly.O nt he other hand, the long range magnetic order completely disappears in all chargeds tates (red curves).…”

“…[3][4][5] Therea re two methods to use the void spaces (i.e.,p ores)i nM OFs/PCPs:b yp re-organizing functional molecules in the pores during the self-assembly syntheticp rocess (for the design of statically controlled functionality), or by insertingf unctional molecules into the pores after framework formationt oa ttempt the guest-induced dynamic control of the functionality.B ased on the formers trategy,b i -or synergistic functions, such as metallic ferromagnets, [6] chiral magnets, [7,8] and switchable ferroelastic transitions, [9] have been demonstrated, in which functionalities in the framework and the molecules or molecular array in the pores mutuallyi nteract to induce as pecific characteristic. [10] Meanwhile, the latter strategy is acurrent growing interest, in which physical properties of frameworks, such as electronic, [11,12] magnetic, [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] and spectroscopic properties [31,32] are modulated by guest molecules/ionsi nsertedi nto the nano-sized pores of the frameworks after framework formation.H owever, the development of MOF/PCP materials, where these technical strategies are assembled in as ingle system, is crucial for the creationo fa finely tuned and accessible functional molecular system.F igure 1a shows an example in which at rigger molecule for the activation/inactivationo faframework function is inserted into the pores during the self-assembly process, which inactivates framework function through host-guest interactions (step-A). The trigger molecule is modulated by an externals timulus,o r ac hemical perturbation, to activate the anticipated framework-function (step-B).…”