Stabilizing Lattice Oxygen in Li-Rich Layered Cathodes by Boron-Doping Induced Anchoring Effect

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Li-rich Mn-based layered oxides (LRMLOs) offer high specific capacity and energy density for next-generation batteries.
• Sluggish kinetics and poor reversibility of oxygen anion redox reactions hinder the practical application of LRMLOs.

Purpose of the Study:

• To investigate the efficacy of interstitial boron doping as a strategy to enhance the electrochemical performance of LRMLOs.
• To stabilize oxygen redox reactions and improve the cyclability of LRMLO cathodes.

Main Methods:

• Interstitial boron doping was employed to introduce B atoms into the LRMLO structure, forming BO4 coordination.
• Multiscale characterization techniques were used to analyze structural and electronic changes.
• Electrochemical evaluations and Density Functional Theory (DFT) calculations were performed to assess performance and mechanisms.

Main Results:

• Boron doping created robust BO4 structures with enhanced B-O covalency, reducing oxygen Bader charges and increasing oxygen vacancy formation energy.
• Electrochemical tests showed a 19.3% enhancement in capacity retention (63.6% after 50 cycles at 0.05 C) compared to undoped samples.
• DFT calculations confirmed that boron incorporation downshifts the O 2p-band center and reduces average oxygen Bader charge, mitigating oxygen release.

Conclusions:

• Interstitial boron doping effectively suppresses oxygen overoxidation and stabilizes oxygen sublattices in LRMLOs.
• This atomic-level engineering approach significantly improves the cyclability and electrochemical stability of LRMLO cathodes.
• The study presents a viable strategy for achieving high-activity and stable oxygen redox in LRMLO materials for advanced energy storage.