Fig. 1

Schematic diagram of key scientific issues and research strategies of Li-rich layered oxide cathode materials"

Fig. 2

(a) Schematic diagram of energy conversion; (b) Bond length changes of different redox activities due to different forms of electrical energy converted to chemical energy during charging; (c) Oxygen-oxygen bond lengths in different oxygen states; (d) K-edge extended X-ray absorption fine structure (EXAFS) spectra of Mn for NCM11X (X = 1, 2, 3, 4, 6) samples when charged to 4.8 V; (e) EXAFS spectra based on the fitted Mn—O bond lengths; (f) Differential scanning calorimetry (DSC) curves of different compositions of cathode materials in the charged state (charged to 4.8 V) [5]"

Fig. 3

(a) Schematic of the atomic coordination structure centered on the oxygen atom; (b) K-edge EXAFS of Ni2+, Co3+, and Mn4+ for NCM11X (X = 1, 2, 3, 4, 6) samples; (c) Fitted coordination numbers of Ni2+, Co3+, and Mn4+ in the second coordination shell; (d) Calculated ratio of Co3+ content in M phase to total Co3+ content (black), and the ratio of Co3+ content in M phase to total transition metal cations in M phase (blue); (e) Energy band structure diagram of the structural domains of the cobalt-containing Li-rich phase [6]"

Fig. 4

(a) Schematic of size effect; (b) Scanning transmission electron microscopy-high angle annular dark field (STEM-HAADF) of micrometer-sized samples after 200 cycles; (c) Results of Li concentration distribution in charged and discharged states of particles with different particle size sizes obtained by finite element analysis (FEA) [9]; Structural evolutions of Li-rich manganese-based cathode materials with aggregation of Li2MnO3 domain during cycling in (d) and (e); (f) Cycling performance at 0.2C[10]; (g) Schematic of cation arrangement of Li-rich layered oxides in the presence of Mn3+[11]"

Fig. 5

(a) Schematic illustration of bulk and surface structure with atomic-layer-deposition technique after heat and the phase delocalization in Li-rich layered cathodes[18]; (b) Oxygen profiles in in-situ differential electrochemical mass spectrometry (DEMS) of pristine and gas-solid interface-modified Li-rich layered oxides with initial charging and discharging[17]; (c) Oxygen profiles in DEMS of Li-rich layered oxides initially charged and discharged after optimization of bulk-phase crystal domain distribution[18]"

Fig. 6

(a) Normalized charge-discharge curves of cycled electrodes of Li-rich layered oxides after annealing at different temperatures; (b) Enlarged in situ temperature-dependent synchrotron X-ray diffraction (TD-SXRD) and schematic diagrams of the metastability state of cycled electrodes of Li-rich layered oxides after annealing [20]; (c) Schematic diagrams of the pristine Li-rich layered oxides and Li-rich complex oxides with a high concentration of defects after deep chemical delithiation; (d) Aberration-corrected high-angle annular dark-field (HAADF)-scanning transmission electron microscopy (STEM) image of high concentration of defective material; (e) Average discharge voltage versus number of cycles curves of pristine and high-concentration defective materials [23]; (f) high Li/O ratio of Li-rich layered oxide materials with highly disordered schematic; (g) Cycling capacity and average discharge voltage of highly disordered Li-rich layered oxides [24]"

Fig. 7

(a) Photographs of a 20 Ah full battery with a Li-rich cathode ||silicon based anode system; (b) First charge/discharge curves of a 20 Ah full battery with a Li-rich cathode||silicon based anode system; (c) Cycling performance of a 20 Ah full battery with a Li-rich cathode||silicon based anode system [25]; (d) Photographs of a 10 Ah full battery with a Li-rich cathode||metal Li negative system; (e) First charge/discharge curves of a 10 Ah full battery with a Li-rich anode||metal Li negative system; (f) Cycling performance of a 10 Ah full battery with a Li-rich layered cathode || Li metal anode system [26]"