## 4 Discussion  
Manganese hexacyanoferrate material is being considered as a potential alternative to traditional chemistries for large-scale rechargeable batteries. The adopted electrochemical protocol aims at simulating BMS malfunctioning and investigating the structural and chemical effects on manganese hexacyanoferrate. Although the electrochemical efficiency for the first cycle results was significantly affected, the overall local structural environment around each photo absorber, i.e., Mn and Fe, was not severely damaged. The state of charge after the protocol differs from the pristine state as expected and consists of an additional spectral contribution, labeled \"Component 2\" in the MCR-ALS analysis. The charge state C\({}_{1}\) and Component 3 (from the MCR-ALS analysis) were both fitted by considering an asymmetric Mn-environment because of the trivalent oxidation state of Mn and the respective JT distortion. MCR-ALS suggests that Component 2 is not exclusively present during cycling. However, the identification of the spectrum of the pure component allowed an EXAFS analysis; the differences in equatorial/axial Mn-N bond lengths are reduced when compared to Component 1, where the respective difference amounts to 0.26 A. The protocol has, therefore, both an electrochemical and structural effect on the system, especially at the beginning of the cycling. The eventual recovery of electrochemical performance after a BMS malfunction is of great importance for technological applications and needs to be further explored, for long-term cycling as well.  
The following are available online at [[http://www.mdpi.com/2076-3417/10/21/7573/s1](http://www.mdpi.com/2076-3417/10/21/7573/s1)]([http://www.mdpi.com/2076-3417/10/21/7573/s1](http://www.mdpi.com/2076-3417/10/21/7573/s1)): Figure S1: Current density profile; Figure S2: Magnification of the spectra at the Fe K-edge for D\({}_{0}\), C\({}_{1}\), and D\({}_{1}\) states of charge; Figure S3: Magnification of the comparison between the spectra at the Fe K-edge for the initial, charged, and discharged states of charge; Figure S4: PCA analysis highlights the need to use at least 3 different spectral components to describe entirely both datasets.  
Conceptualization, M.G., S.P., and A.M.; methodology, M.G. and A.M.; investigation--X-ray absorption spectroscopy measurements, A.M., S.B., L.S., and M.G.; data curation--MCR-ALS, L.S.; data curation--EXAFS analysis, M.G.; data curation--XANES analysis, A.M.; writing--original draft preparation, A.M. and M.G.; writing--review and editing, all authors; funding acquisition, M.G., L.S., and S.P. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the University of Bologna, RFO Funding (M.G.) and by the Synchrotron SOLEIL through project #20171297. The HIU authors acknowledge the basic funding of the Helmholtz Association.  
Figure 6: EXAFS fitting analysis on (**a**) the most relevant states of charge, i.e., D\({}_{0}\), C\({}_{1}\), and D\({}_{1}\), as well as (**b**) all three components retrieved by the MCR-ALS analysis. The experimental Fourier transform signal is compared to the calculated one in all instances. (**c**,**d**) Examples of contour plots for the error parameter determination. These refer to highly correlated parameters; the inner elliptical circle corresponds to a 95% confidence level.  
**Acknowledgments:** This work was supported by a public grant overseen by the French National Research Agency (ANR) as part of the \"Investissements d'Avenir\" program (reference: ANR10-EQPX45).  
**Conflicts of Interest:** The authors declare no conflict of interest.