Reversible Li storage for nanosize cation/anion-disordered rocksalt-type oxyfluorides: LiMoO 2 – x LiF (0 ≤ x ≤ 2) binary system

Material Design Concept of Lithium‐Excess Electrode Materials with Rocksalt‐Related Structures for Rechargeable Non‐Aqueous Batteries

“…Therefore, the formation of solid solution samples (Li 1+ x MoO 2 F x or Li 1+ x Mo 1− x O 2−2 x F 2 x ) is anticipated, and the highest reversible capacity (based on the Mo 3+ /Mo 6+ redox) is expected for Li 3 MoO 2 F 2 ( x =2). Indeed, a uniform distribution of Mo/O/F is clearly noted by EDX mapping after mechanical milling as shown in Figure , and the formation of a single phase sample with low crystallinity is further confirmed by XRD . If all lithium ions are reversibly extracted from the crystal lattice with the three‐electron redox of Mo, the theoretical capacity reaches 430 mA h g −1 .…”

“…Recently, our group has extended the concept of three‐electron redox of Mo 3+ /Mo 6+ to the oxyfluoride, and relatively low electrochemical potential of Mo redox (2–3 V vs. Li) is effectively increased by partial substitution of fluoride ions for oxide ions . Lithium molybdenum oxyfluorides were prepared from a mixture of LiMoO 2 and LiF.…”

Advances in the Cathode Materials for Lithium Rechargeable Batteries

“…Moreover,asFhas higher electronegativity than O, it can increase the average discharge voltage (i.e., energy density) by an inductive effect. [197,200] Thepotential of fluorination has been reported by several research groups since the discovery of the novel disordered rock salt Li 2 VO 2 F cathode which showed over 400 mAh g À1 . [50] Further elemental modification was conducted and the Li 2 V x Cr 1Àx O 2 Fo xyfluoride cathode showed an improved discharge voltage with participation of high voltage Cr redox (3.5 V).…”

“…Note that despite its merits,F À doping is reported to result in materials that have atendencytocapture Li + ,which can cause sub-theoretical capacity due to strong Li-F bonding. [200] Thea mount of F À doping is therefore,c arefully controlled in each system.…”

Li2O:Li–Mn–O Disordered Rock‐Salt Nanocomposites as Cathode Prelithiation Additives for High‐Energy Density Li‐Ion Batteries

“…Li 2/3 Mn 1/3 O 5/6 is part of an emerging family of Li‐rich cathode materials based on disordered RS structures, displaying higher capacities (200–350 mAh g −1 ) than Li‐rich layered oxides (150–250 mAh g −1 ). Besides their superior capacities, disordered RS offers a versatile chemical playground and several disordered RS compositions have been reported over the last few years that can present multivalent transition metals, mixed O 2− /F − anions, or oxygen redox …”