LiCaFeF 6 : A zero-strain cathode material for use in Li-ion batteries

Abstract

A new zero-strain LiCaFeF6 cathode material for reversible insertion and extraction of lithium ions is presented. LiCaFeF6 is synthesized by a solid-state reaction and processed to a conductive electrode composite via high-energy ball-milling. In the first cycle, a discharge capacity of 112 mAh g-1 is achieved in the voltage range from 2.0 V to 4.5 V. The electrochemically active redox couple is Fe3+/Fe2+ as confirmed by Mössbauer spectroscopy and X-ray absorption spectroscopy. The compound has a trigonal colqu c). By means of in situ and ex situ XRD as well as X-ray absorption fine structure spectroscopy a reversible response to Li uptake/release is found. For an uptake of 0.8 mole Li per formula unit only minimal changes occur in the lattice parameters causing a total change in unit cell volume of less than 0.5 %. The spatial distribution of cations in the crystal structure as well as the linkage between their corresponding fluorine octahedra is responsible for this very small structural response. With its zero-strain behaviour this material is expected to exhibit only negligible mechanical degradation. It may be used as a cathode material in future lithium-ion batteries with strongly improved safety and cycle life.

Conductive Li3.08Cr0.02Si0.09V0.9O4 Anode Material: Novel “Zero‐Strain” Characteristic and Superior Electrochemical Li+ Storage

“…However, the small interfacial lattice train between the two phases can gradually accumulate and finally lead to mechanical damage after long‐term cycling. [ 11 ] In contrast, the “zero‐strain” γ‐LCSVO compound with a solid‐solution reaction can efficiently avoid this issue, due to the reduced lattice distortion and strain during the solid‐solution reaction. Therefore, the solid‐solution type “zero‐strain” characteristic of γ‐LCSVO undoubtedly corresponded to its excellent cycling stability.…”

Interfaces in Garnet‐Based All‐Solid‐State Lithium Batteries

“…[ 137 ] For most electrodes, the volume change will take place during lithiation and delithiation process ( Figure 13 A). [ 138 ] During lithiation process, the active material undergone crystal expansion. Mechanical degradation of SEs was caused by intercalation‐induced expansion of electrode particles, within the constrain of a dense solid‐state electrode.…”

Li2Ni0.2Co1.8O4 having a spinel framework as a zero-strain positive electrode material for lithium-ion batteries

“…16,17 Thus far, only a few zero-strain materials have been reported. [18][19][20][21][22][23][24][25][26] These materials showed very small or no change in lattice dimension during lithium or sodium insertion/extraction. Their crystal structures have a large space that can accommodate Li ions, which effectively suppresses dimensional change during lithium insertion.…”

“…The volumetric capacity and dimensional change of zerostrain Li2Ni0.2Co1.8O4 was compared with those of other lithium insertion materials (Figure 13). 10,[18][19][20]22,24,36,[40][41][42][43][44] All zero-strain materials except LTO has a crystal structure with a large space that can accommodate Li ions. Such a large space is expected to reduce lattice distortion during lithium insertion/extraction, leading to a small dimensional change.…”