Despite the imminent commercial introduction of Li-ion batteries in electric drive vehicles and their proposed use as enablers of smart grids based on renewable energy technologies, an intensive quest for new electrode materials that bring about improvements in energy density, cycle life, cost, and safety is still underway. This Progress Report highlights the recent developments and the future prospects of the use of phases that react through conversion reactions as both positive and negative electrode materials in Li-ion batteries. By moving beyond classical intercalation reactions, a variety of low cost compounds with gravimetric specific capacities that are two-to-five times larger than those attained with currently used materials, such as graphite and LiCoO(2), can be achieved. Nonetheless, several factors currently handicap the applicability of electrode materials entailing conversion reactions. These factors, together with the scientific breakthroughs that are necessary to fully assess the practicality of this concept, are reviewed in this report.

Beyond Intercalation-Based Li-Ion Batteries: The State of the Art and Challenges of Electrode Materials Reacting Through Conversion Reactions

2.4.2. Interpenetrated Ladders 711 2.4.3. Unusual Motifs of Ladders 713 2.4.4. Properties of Ladderlike Chains 713 2.5. Rotaxane Polymers 714 2.5.1. 1D Polyrotaxanes 714 2.5.2. 2D Polyrotaxanes 715 2.5.3. 3D Polyrotaxanes 716 2.5.4. Hydrogen-Bonded Polyrotaxanes 716 2.6. Ribbon/Tape Polymers 717 2.7. Metal Cluster As Building Blocks for 1D CP 718 2.7.1. Metal Carboxylate Clusters 718 2.7.2. Metal Halide Clusters 719 2.7.3. Metal Chalcogenide Clusters 720 2.7.4. Polyoxometalate Clusters 721 2.7.5. Single Molecular Magnets as Building Blocks 722

One-Dimensional Coordination Polymers: Complexity and Diversity in Structures, Properties, and Applications

During the charging and discharging of lithium-ion-battery cathodes through the de- and reintercalation of lithium ions, electroneutrality is maintained by transition-metal redox chemistry, which limits the charge that can be stored. However, for some transition-metal oxides this limit can be broken and oxygen loss and/or oxygen redox reactions have been proposed to explain the phenomenon. We present operando mass spectrometry of (18)O-labelled Li1.2[Ni0.13(2+)Co0.13(3+)Mn0.54(4+)]O2, which demonstrates that oxygen is extracted from the lattice on charging a Li1.2[Ni0.13(2+)Co0.13(3+)Mn0.54(4+)]O2 cathode, although we detected no O2 evolution. Combined soft X-ray absorption spectroscopy, resonant inelastic X-ray scattering spectroscopy, X-ray absorption near edge structure spectroscopy and Raman spectroscopy demonstrates that, in addition to oxygen loss, Li(+) removal is charge compensated by the formation of localized electron holes on O atoms coordinated by Mn(4+) and Li(+) ions, which serve to promote the localization, and not the formation, of true O2(2-) (peroxide, O-O ~1.45 A) species. The quantity of charge compensated by oxygen removal and by the formation of electron holes on the O atoms is estimated, and for the case described here the latter dominates.

Charge-compensation in 3d-transition-metal-oxide intercalation cathodes through the generation of localized electron holes on oxygen

Lithium extraction/insertion in LiFePO4: an X-ray diffraction and Mössbauer spectroscopy study

It is desirable to develop electrode materials for advanced rechargeable batteries with low cost, long life, and high-rate capability. Pyrite FeS2, as an easily obtained natural mineral, has been already commercialized in primary lithium batteries, but encountered problems in rechargeable batteries with carbonate-based electrolytes due to the limited cycle life caused by the conversion-type reaction (FeS2 + 4M → Fe + 2M2S (M = Li or Na)). Herein, we demonstrate that FeS2 microspheres can be applied in room-temperature rechargeable sodium batteries with only the intercalation reaction by simultaneously selecting a compatible NaSO3CF3/diglyme electrolyte and tuning the cut-off voltage to 0.8 V. A surprisingly high-rate capability (170 mA h g−1 at 20 A g−1) and unprecedented long-term cyclability (∼90% capacity retention for 20 000 cycles) has been obtained. We suggest that a stable electrically conductive layer-structured NaxFeS2 was formed during cycling, which enables the highly reversible sodium intercalation and deintercalation. Moreover, 18650-type sodium batteries were constructed exhibiting a high capacity of ∼4200 mA h (corresponding to 126 W h kg−1 and 382 W h L−1) and a capacity retention of 97% after an initial 200 cycles at 4 A during charge–discharge. This shows that the production of rechargeable sodium batteries with FeS2 microspheres is viable for commercial utilization.

Pyrite FeS2 for high-rate and long-life rechargeable sodium batteries

The charge and discharge mechanisms of Li/FeS{sub 2} and Li/Li{sub 2} FeS{sub 2} cells near room temperature are studied by in situ x-ray diffraction and in situ {sup 57}Fe Mossbauer spectroscopy. The electrochemical behavior of these cells are compared, and their cell reactions are described, For 0{lt}x{le}0.8, the cycling behavior of Li{sub 2 {minus} x} FeS{sub 2} is reversible. However, for x{gt}0.8, structural decomposition of Li{sub 2 {minus} x} FeS{sub 2} occurs, and disproportionation to nonstoichiometric FeS (FeS{sub y}) and S is observed. Similarly, when Li/FeS{sub 2} cells are recharged to 2.8V, the cathode is a mixture of FeS{sub y} and S. Examination of the mixture by differential scanning calorimetry shows that FeS{sub y} and S react to form FeS{sub 2} above 200{degrees}C. This explains why high temperature Li/FeS{sub 2} cells reversibly while ambient temperature Li/FeS{sub 2} cells show poor reversibility.

https://iopscience.iop.org/article/10.1149/1.2096426/pdf

Electrochemistry of Pyrite‐Based Cathodes for Ambient Temperature Lithium Batteries

Mössbauer studies of iron-bearing minerals in coal and coal ash

Les diagrammes de rayons X d'echantillons pulverises de Li 2 FeS 2 , prepares au laboratoire, presentent des parametres cristallins en accord avec ceux reportes anterieurement (non-observation d'un super reseau d'ordre n). Les intensites des pics ne peuvent etre expliquees en admettant que les atomes Fe et S sont dans la structure CdI 2 . Les calculs suggerent que les ions ont une coordination tetraedrique

C. H. W. Jones

Papers

Electrochemistry of Pyrite‐Based Cathodes for Ambient Temperature Lithium Batteries

Mössbauer studies of iron-bearing minerals in coal and coal ash

Crystal structure of Li2FeS2

A spectroscopic investigation of some organotellurium—mercury(II) complexes

A study of pyrite-based cathodes for ambient temperature lithium batteries by in situ57Fe Mossbauer spectroscopy