Fig 1

(a) Schematic diagram of developing from TM redox to lattice oxygen redox [14]. (b) Schematic diagram of Li–O–Li and b1* configurations. (c) Several possible coordination structures with different stability in LLOs. (d) Schematic diagram of LLOs and HM-LLOs. (e) Microstructure of HM-LLOs and LLOs [21]. (f) Differential capacitance curves of HM-LLOs and LLOs. (a) Adapted with permission from Ref. [14], Copyright American Chemical Society. (e) Adapted with permission from Ref. [21], Copyright 2023 Springer Nature."

Fig 2

(a) Schematic diagram of LMCT. (b) Schematic diagram of the aggregation of C2/m phase in LLOs [8]. (c) Schematic diagram of Li+ ion migration resistance of LLOs and HM-LLOs. (d) Schematic diagram of spontaneous aggregation of O–O on the surface of HM-LLOs. (e) Schematic diagram of the formation of O–O dimer in bulk [40]. (f) Schematic diagram of oxygen permeation network formation [46]. (g) Schematic diagram of reasons for low actual capacity. (b) Adapted with permission from Ref. [8], Copyright 2020, Wiley. (e) Adapted with permission from Ref. [40], Copyright 2016, Royal Society of Chemistry. (f) Adapted with permission from Ref. [46], Copyright 2024, Wiley."

Fig 3

(a) Schematic diagram of lithiation of precursors with different morphologies [52]. (b) Schematic diagram of co-precipitation process. (c) Schematic diagram of different primary particles with the same secondary release irreversible oxygen. (d) Schematic diagram of different secondary particles with the same primary particle release irreversible oxygen. (e) Schematic of HMLLO-NM13 with high active surface exposure. (f) Schematic diagram of precursor synthesis with boron [60]. (a) Adapted with permission from Ref. [52], Copyright 2024 Wiley. (f) Adapted with permission from Ref. [60], Copyright 2022, American Chemical Society."

Fig 4

(a) Schematic diagram of structural changes with increasing sintering temperature. (b) Schematic diagram of particle growth with increasing sintering temperature or time. (c) Two-step heat treatment process to prepared larger HMLLO-NM13 particles. (d) Schematic diagram of Li2MnO3-like domain evolution of LLO governed by synthetic pathways depending on Li sources [69]. (e) Schematic diagram of adjusting oxygen partial pressure during the sintering process. (d) Adapted with permission from Ref. [69], Copyright 2024, Royal Society of Chemistry."

Fig 5

(a) Schematic diagram of doping sites and their resulting doping effects. (b) Schematic diagram of doping via saltwater quenching [76]. (c) The doping elements and their doping sites in this chapter. (b) Adapted with permission from Ref. [76], Copyright 2024, The Royal Society of Chemistry."

Fig 6

Schematic diagram of index for evaluating doping results: (a) Disorder [85]. (b) Overlap of TM with O 2p. (c) Schematic diagram of π back-donation mechanism. (d) Synergy effect. (e) Li–O–M configuration. (a) Adapted with permission from Ref. [85], Copyright 2023, American Chemical Society."

Fig 7

(a) ALD coating schematic diagram. (b) Schematic diagram of oleic acid treatment for HMLLO-NM13 and processed structure [114]. (c) Schematic diagram of pre-oxidation and mechanism [123]. (b) Adapted from Ref. [114], Copyright 2021, Wiley. (c) Adapted with permission from Ref. [123], Copyright 2023, Wiley."

Fig 8

(a) Schematic diagram of template method for preparing hollow HMLLO-NM13. (b) SEM image of HM-LLOs by ball milling. (c) Schematic diagram of OAD. (d) Schematic diagram of hydrothermal preparation of high exposure active surface HM-LLOs."

Fig 9

(a) Schematic of the cross-section of a Li1+X(r)M1−X(r)O2 particle. (b) Schematics of the band structure: Li1.2Mn0.6Ni0.2O2 which generates irreversible oxygen, and Li1.2Mn0.6Ni0.2O2−δ which has better oxygen stability. (c) Schematic diagram of electron cloud distribution of oxygen and sulfur hosts [144]. (d) Schematic diagrams of O2-type crystal structure [149]. (e) Schematic diagram of dispersed C2/m phase [8]. (c) Adapted with permission from Ref. [144], Copyright 2024, American Chemical Society. (d) Adapted with permission from Ref. [149], Copyright Fu, Y. et al. (e) Adapted with permission from Ref. [8], Copyright 2020 Wiley."

Fig 10

Schematic diagram of overall optimization strategy. Form Preparation of precursor to regulation of sintering conditions. And material modification consists of doping, surface engineering."