Stabilized Anionic Redox by Rational Structural Design from Surface to Bulk for Long‐Life Fast‐Charging Li‐Rich Oxide Cathodes

Abstract

On account of high capacity and high voltage resulting from anionic redox, Li‐rich layered oxides (LLOs) have become the most promising cathode candidate for the next‐generation high‐energy‐density lithium‐ion batteries (LIBs). Unfortunately, the participation of oxygen anion in charge compensation causes lattice oxygen evolution and accompanying structural degradation, voltage decay, capacity attenuation, low initial columbic efficiency, poor kinetics, and other problems. To resolve these challenges, a rational structural design strategy from surface to bulk by a facile pretreatment method for LLOs is provided to stabilize oxygen redox. On the surface, an integrated structure is constructed to suppress oxygen release, electrolyte attack, and consequent transition metals dissolution, accelerate lithium ions transport on the cathode–electrolyte interface, and alleviate the undesired phase transformation. While in the bulk, B doping into Li and Mn layer tetrahedron is introduced to increase the formation energy of O vacancy and decrease the lithium ions immigration barrier energy, bringing about the high stability of surrounding lattice oxygen and outstanding ions transport ability. Benefiting from the specific structure, the designed material with the enhanced structural integrity and stabilized anionic redox performs an excellent electrochemical performance and fast‐charging property..

Enabling Ultrastable Co-Free Li-Rich Oxides via TbF3 Treatment

“…Therefore, distinct diffraction peaks observed between 20° and 25° indicate that both the pristine LRNMO and its modified sample with an ordered structure of excessive Li + in the TM layer have been successfully synthesized. Furthermore, the clear separation of the (108)/(110) and (006)/(102) diffraction peaks demonstrates the high crystallinity and layered structure of the materials. , The ratio of the intensity of the (003) peak to the (104) peak provides insight into the extent of Li + /Ni 2+ mixing within the layered configuration. The larger the ratio of I (003) to I (104) is, the higher the degree of cation order, and the more stable the structure will be.…”

“…Furthermore, the clear separation of the (108)/ (110) and ( 006)/(102) diffraction peaks demonstrates the high crystallinity and layered structure of the materials. 30,31 The ratio of the intensity of the (003) peak to the (104) peak provides insight into the extent of Li + /Ni 2+ mixing within the layered configuration. The larger the ratio of I (003) to I (104) is, the higher the degree of cation order, and the more stable the structure will be.…”

Simultaneous dual modification of Li-rich Mn-based cathode in restraining oxygen release and structure distortion

“…Notably, previous literature has suggested that boron (B) ions at transition metal (TM) lattice sites easily locate to interstitial sites to form tetrahedral BO 4 , which is more stable than other lattice structures, and Xiao et al combined density functional theory (DFT) and neutron powder diffraction (NPD) experimental results to confirm that B is doped into interstitial sites to form BO 4 structures. 22–25 Therefore, our predictions for doping sites primarily focused on the cerium element. 26–28 As shown in Fig.…”

“…19 Meanwhile, boron (B) doping significantly affects cathode materials because B dopes into interstitial sites to form strong covalent B–O bonds, resulting in more negative charges on oxygen, thereby reducing oxygen transition oxidation and inhibiting irreversible structural changes during cycling. 20,21 To the best of our knowledge, the synergistic effect of boron and high-valence elements has not been utilized to adjust the internal electronic structure and structural stability of cathode materials.…”

“Mn-locking” effect by anionic coordination manipulation stabilizing Mn-rich phosphate cathodes

“…[1][2][3][4][5][6] The currently widely used lithium-ion batteries (LIBs) might be a candidate for this purpose. [7][8][9][10] However, they will be excluded when the limited lithium resources and underlying political disputes are taken into consideration. [11][12][13] Sodium-ion batteries (SIBs) emerge as promising alternatives due to the omnipresent availability of Na resources.…”