Improved cyclic stability of LiNi0.8Mn0.1Co0.1O2 cathode enabled by a novel CEI forming additive

Nickel-rich layered oxide cathodes, such as LiNi₀.₈Mn₀.₁Co₀.₁O₂ (NMC811), are promising for next-generation lithium-ion batteries due to their high energy density. However, these materials suffer from interfacial side reactions and structural degradation during cycling, leading to capacity fading and poor long-term stability. Electrolyte engineering, particularly the use of film-forming additives, has been recognized as an effective strategy to stabilize the cathode-electrolyte interphase (CEI) and improve electrochemical performance.

A study published in Frontiers in Energy by researchers from Shanghai Jiao Tong University, led by Zulipiya Shadike and Junliang Zhang, introduces a novel boron-based electrolyte additive—tris(2,2,2-trifluoroethyl) borate (TTFEB)—to enhance the cyclic stability of NMC811 cathodes. The work systematically compares TTFEB with other boron-based additives and identifies its superior ability to form a stable, LiF-rich CEI.

Electrochemical tests show that cells with 1% TTFEB retain 72.8% of their capacity after 350 cycles at 1 C, significantly outperforming cells using baseline electrolytes (59.7%). Through multi-model diagnostics including XPS, TOF-SIMS, and TEM, the team revealed that TTFEB promotes a thin, uniform, and boron-containing CEI rich in LiF. This interphase facilitates lithium-ion transport, reduces interfacial resistance, and suppresses transition metal dissolution and surface reconstruction. Moreover, TTFEB aids in lithium salt dissociation, further improving rate capability.

This study provides a feasible strategy for regulating interphasial chemistry in nickel-rich cathodes via a novel fluorine-functionalized borate additive. The findings offer valuable insights for designing electrolyte components aimed at improving the performance of high-energy lithium-ion batteries.

Original source:

https://link.springer.com/article/10.1007/s11708-024-0953-5

https://journal.hep.com.cn/fie/EN/10.1007/s11708-024-0953-5

Shareable link：

https://rdcu.be/eRYYt

Keywords:

NMC811 / cathode electrolyte interphase / film forming additives / cyclic stability