Rational Design of a Li-Rich Hybrid Cathode with a 3D Interstitial Network for Reversible Oxygen Redox

1. Research Background

Li-rich manganese-based layered oxide cathodes (LRM/LMNO) are considered one of the most promising candidates for next-generation high-energy-density lithium-ion batteries, owing to their high specific capacity and low cost. However, LRM materials face multiple challenges in practical application: the characteristic Li-O-Li configuration that enables anionic redox activity also drives irreversible oxygen release, causing first-cycle capacity loss; during deep delithiation, transition metals readily migrate from octahedral sites in the layered structure into tetrahedral sites within the lithium layer, triggering irreversible transformation of the layered phase into spinel or rock-salt phases; oxygen loss further reduces transition-metal valence states, causing continuous voltage decay; and the inherently low ionic conductivity and sluggish oxygen-anion redox kinetics of the Li₂MnO₃ component severely constrain rate performance.

Conventional modification strategies — doping, surface coating, heterostructure design, and crystal-facet engineering — offer some improvement but often require complex precursors and cumbersome processing. More importantly, single-material modification struggles to simultaneously resolve structural instability, ion-transport kinetics, interfacial side reactions, and low compaction density together. Developing electrode-level synergistic design strategies — achieving performance complementarity through physical coupling of different material systems — therefore carries significant scientific and engineering value.

2. Article Overview

Prof. Yuefeng Su, Assoc. Prof. Lai Chen, and Dr. Jinyang Dong’s team at Beijing Institute of Technology have proposed an electrode-level physical blending design strategy: physically mixing micron-scale Li-rich layered oxide cathode (LMNO) with nanoscale, rigid Ni-based disordered rock-salt cathode material (DRX), followed by low-temperature heat treatment, successfully constructing a hybrid cathode (LMDR) with a 3D interstitial network for cathode materials.

In this design, LMNO functions as the structural “pillar” that provides the primary capacity contribution and layered diffusion scaffold, while the additionally introduced DRX particles embed uniformly within the inter-particle gaps of LMNO, forming a percolating network that simultaneously enhances ion/electron transport and redistributes mechanical stress. This spatial synergistic coupling effectively regulates the local chemical and mechanical environment, enabling reversible oxygen redox, suppressing oxygen release and transition-metal dissolution, and mitigating stress accumulation during cycling.

The optimized LMDR-10 cathode demonstrates superior initial Coulombic efficiency, enhanced cycling stability, reduced voltage decay, and excellent rate performance. This work, titled “Rational Design of Li-Rich Hybrid Cathodes with Stiff Redox-Active Interstitial Networks Enabling Local Environment Engineering for Reversible Oxygen Redox,” was published in Energy Storage Materials (2026, 88, 105121).

3. Article Highlights

3.1 Structure, Morphology, Compaction Density, and Conductivity

Figure 1. LMDR structure, morphology, and compaction density/conductivity test results.

Results show that construction of the LMDR rigid network does not alter the phase composition or lattice parameters of the individual components, and LMDR-10 achieves uniform distribution of all constituents. Compaction density and powder resistance testing show that LMDR effectively increases electrode density while reducing overall resistance — a direct benefit for volumetric energy density and rate capability in the finished cell. The material’s compaction density and powder resistance were tested using the Powder Resistivity & Compaction Density Tester (PRCD1100) from IEST Instrument.

Figure 2. Official acknowledgments excerpt from Energy Storage Materials (2026) — Beijing Institute of Technology research team acknowledges IEST Instrument‘s support for compaction density and conductivity testing.

3.2 Electrochemical Performance

Figure 3. (a) The cycling performance of all samples at 1 C between 2.0–4.6 V; The dQ/dV curves during discharging process of LMNO, LMDR-5, LMDR-10, and LMDR-15; GITT curves and the calculated Li+ diffusion coefficients of LMNO, LMDR-5, LMDR-10, and LMDR-15; (j) Average discharge voltage profiles of all samples at 1 C between 2.0–4.6 V; (k) Rate performance of all samples.

Electrochemical testing results show that after 300 cycles at 1C, LMDR-10 exhibits improved capacity retention and reduced voltage decay relative to pristine LMNO. dQ/dV analysis indicates that LMDR-10 effectively suppresses the irreversible transformation of the layered phase into the spinel phase. GITT testing confirms that LMDR-10 increases the lithium-ion diffusion coefficient. LMDR-10 also shows improved rate capability across increasing current densities.

3.3 Oxygen Redox Behavior: DEMS, In-Situ EIS, and Soft X-Ray Absorption Spectroscopy

Figure 4. DEMS of O₂ and CO₂ of LMNO and LMDR-10; In situ EIS of LMNO and LMDR-10 during charging process; (e) The fitting results of R_ct and R_s during charging process; Normalized soft XAS spectra at selected voltage during the initial and second cycle of O K-edge of LMNO and LMDR-10; (h) Intensity ratio of OKL/OKH from the actual test results.

DEMS (differential electrochemical mass spectrometry) shows that oxygen redox reversibility is improved in LMDR-10. In-situ EIS reveals that interfacial side reactions are effectively suppressed in LMDR-10. O K-edge soft X-ray absorption spectroscopy analysis shows that the TM-O framework structural stability is enhanced in LMDR-10. Together, these results confirm that the LMDR design achieves a stabilized surface structure and regulated anionic redox activity, thereby improving overall electrochemical stability.

3.4 Multiscale Post-Cycling Characterization

Figure 5. Nyquist plots of different samples at initial cycle and 100th cycle; Raman spectra after 100 cycles of LMNO, LMDR-5, LMDR-10, and LMDR-15; Atomic force microscopy (AFM) images showing DMT modulus of LMNO and LMDR-10 after cycling; XPS spectra after 100 cycles of O 1 s in LMNO and LMDR-10; Contour plots of the Mn K-edge WT-EXAFS spectra of cycled LMNO and LMDR-10.

Multiscale characterization of cycled electrodes provides further insight into LMDR-10’s advantages: phase transformation in LMDR-10 is significantly suppressed, stress distribution is more uniform, lattice oxygen signal intensity is higher after cycling, and Mn-O and Mn-Mn bond strengths are higher relative to pristine LMNO. Laboratory-scale thick-electrode testing further confirms that LMDR’s advantages persist even at higher areal loading — an important indicator for practical cell-level scale-up.

3.5 COMSOL Simulation: Li-Ion Concentration and Stress Distribution

Figure 6. (a) Simulation diagram of Li-ion concentration distribution for LMNO and LMDR; (b) Simulation diagram of stress distribution for LMNO and LMDR.

COMSOL simulation further demonstrates that the LMDR rigid network produces more uniform lithium-ion concentration and mechanical stress distribution during charge-discharge cycling — significantly mitigating particle microcrack formation and electrode cracking.

LMDR-10 vs Pristine LMNO: Key Performance Metrics

4. Conclusion

This work, through an electrode-level design strategy, successfully integrates micron-scale Li-rich manganese-based layered oxide cathode with nanoscale rigid disordered rock-salt cathode material in a synergistic manner, constructing a cathode material (LMDR) built around a 3D interstitial network for cathode materials. The resulting LMDR-10 demonstrates multiple advantages: high initial Coulombic efficiency, excellent long-term cycling stability, significantly suppressed voltage decay, and outstanding rate performance.

This work offers mechanistic insight into how inter-particle phase coupling and local environment engineering can synergistically stabilize redox chemistry in Li-rich layered oxides, providing a scalable electrode-design paradigm for developing high-energy-density, long-life Li-rich cathode materials.

5. Original Article

Jianan Hao, et al. Rational Design of Li-Rich Hybrid Cathodes with Stiff Redox-Active Interstitial Networks Enabling Local Environment Engineering for Reversible Oxygen Redox. Energy Storage Materials, 2026, 88, 105121.

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