Achieving Excellent Electrochemical Stability of Li‐rich Mn‐Based Cathode by One‐Step Decanoic Acid Treatment Under Ambient Atmosphere

Why It Matters

The technique dramatically improves the cycle life and energy density of Li‑rich cathodes, addressing a key barrier to their commercial adoption in electric‑vehicle batteries.

Key Takeaways

• One-step decanoic acid treatment forms stable surface CEI layer
• DA-LLMO retains 80% capacity after 400 cycles at 2 C
• Initial capacity rises to 293.5 mAh g⁻¹ at 0.1 C
• Oxygen vacancies reduce lattice oxygen loss and voltage decay
• Method applicable to LiCoO₂ and Ni‑rich oxide cathodes

Pulse Analysis

Li‑rich manganese‑based cathodes have attracted attention for their high theoretical capacity, yet practical deployment has been hampered by irreversible lattice oxygen loss, voltage fade, and rapid capacity decay during cycling. Conventional mitigation strategies often involve multi‑step coatings, high‑temperature sintering, or complex washing procedures that add cost and complicate manufacturing. Surface engineering that can simultaneously stabilize the crystal lattice and suppress detrimental side reactions is therefore a critical research focus for next‑generation lithium‑ion batteries.

The decanoic acid (DA) treatment reported in the study offers a remarkably simple solution. By immersing the cathode powder in a decanoic acid solution under ambient conditions, a uniform organic layer adheres to the particle surface, neutralizing residual lithium and fostering the formation of a thin, robust cathode‑electrolyte interphase (CEI). Simultaneously, the process generates controlled oxygen vacancies that act as buffers against oxygen evolution during high‑voltage operation. Electrochemical testing shows the DA‑modified LLMO delivering 293.5 mAh g⁻¹ at 0.1 C and maintaining 80% capacity after 400 cycles at 2 C, a stark improvement over the 44% retention of the pristine material.

Beyond performance gains, the ambient, one‑step nature of the DA coating aligns with scalable manufacturing. No additional sintering, drying, or solvent‑intensive steps are required, reducing energy consumption and production time. The authors also demonstrate the method’s versatility on LiCoO₂ and Ni‑rich oxides, suggesting a broader applicability across the cathode market. As automakers push for higher energy density and longer range, such low‑cost, high‑impact surface treatments could accelerate the transition of Li‑rich cathodes from laboratory to commercial electric‑vehicle batteries.