Tuning Magnetic Symmetry and Properties in the Olivine Series Li_1–xFe_xMn_1–xPO₄ through Selective Delithiation

Abstract

We present the first in-depth study of the nuclear and magnetic structures of the fully lithiated LiFe x Mn 1−x PO 4 solid solutions as well as the partially delithiated Li 1−x Fe x Mn 1−x PO 4 series using neutron powder diffraction. By using a weak oxidizing solution that only oxidizes Fe 2+ , we find that lithium can be removed from these olivines in a stepwise manner. Representational analysis was performed on the observed magnetic reflections and found that the lithiated solid solutions order in the magnetic space group Pnma′, which is identical to triphylite (LiFePO 4 ). We report that, even when removing 20% of the lithium from the hcp lattice, the magnetic structure changes and multiple magnetic contributions are needed to fully encompass the observed magnetic order. We find that the partially delithiated x = 0.2 and 0.3 have a magnetic structure P2 1 ′/n11, and when x surpasses 0.3, the magnetic structure changes to P2 1 2 1 2 1 . We give a detailed report on the effect of delithiation on magnetic order, bond distances/angles, and the super-and supersuperexchange interactions in the material. The symmetries of the magnetic order of these solid solutions are then discussed with regard to their potential as ferrotoroidic candidates.

Tuning magnetoelectricity in a mixed-anisotropy antiferromagnet

“…Tuning of the magnetic symmetry was also recently achieved in the olivine series of compounds, Li 1− x Fe x Mn 1− x PO 4 45 , as well as in Mn and Co doped LiNiPO 4 46 . These studies do not report on the corresponding consequences for the ME effect but they further illustrate that the lithium orthophosphate family harbour many possibilities for tailoring the magnetic and consequently also ME material properties.…”

Sustainable upcycling of mixed spent cathodes to a high-voltage polyanionic cathode material

“…However, these alternative “high-voltage” olivine-type cathodes are far from practical, either because of their poor electrical conductivity or they operate beyond the stable voltage range of the electrolyte. Substituting a transition metal (TM) at Fe 2+ sites in LFP to form a LiFe x TM 1-x PO 4 (such as LiFe x Mn 1-x PO 4 , LFMP) solid solution is considered a promising strategy to increase the working potential 20 – 22 . Spent LIBs rich in these transition metals are important resources and directly upgrading S-LFP and Mn-rich cathode materials to a high-voltage LFMP cathode seems to be a feasible and economical way.…”

Electrochemical Control of Magnetism on the Breathing Kagome Network of LixScMo3O8

“…In particular, magnetic studies have greatly impacted our understanding of complex mechanisms in a host of different material systems by probing the electron spin . Detailed study of the electronic phase diagram of Li x CoO 2 , Li 1– x Fe x Mn 1– x PO 4 , and LiNi 0.8 Mn 0.1 Co 0.1 O 2 using magnetometry has illuminated the sensitive influence of Li content on the complex electronic property evolution in these materials. In some members of the Wadsley-Roth family of fast-charging anode materials, magnetic measurements have been instrumental in supporting a hypothesized insulator to metal transition during cycling. , Advances in operando magnetometry have additionally revealed important insights toward design strategies in Sn-based alloy anodes .…”