In Situ-Constructed Elastomeric Interphase for Grain Boundary Stabilization in High-Voltage Layered Oxide Cathodes.
basic_science · Level V
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- Record sourced from PubMed, PMID 42435321.
- Also identified by DOI 10.1002/adma.74129.
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Abstract
Layered oxide cathodes are a leading class of high-energy-density electrode materials for lithium-ion batteries, but their long-term stability at high voltages is compromised by chemical corrosion and mechanical stress at grain boundaries. Here, we report the construction of an elastic and voltage-tolerant poly(urea-siloxane) (PUSi) coating via the in situ polymerization of amine-terminated polydimethylsiloxane and toluene diisocyanate (TDI). This polymer acted as a conformal artificial interphase that stabilized the secondary-particle surface and internal primary-particle surfaces. The PUSi layer acted as a stable chemical barrier that isolated cathode interfaces from direct contact with the electrolyte. This suppressed interfacial side reactions and inhibited the layered-to-spinel phase transformation. The tailorable elasticity of the PUSi layer allowed it to accommodate cyclic volumetric variations and suppress intergranular cracking during high-voltage cycling. When applied to LiNi<sub>0.6</sub>Co<sub>0.2</sub>Mn<sub>0.2</sub>O<sub>2</sub>, the cathode showed a capacity retention of 81.2% after 450 cycles in coin cells and 82.4% after 200 cycles in Li-metal pouch cells under a cut-off voltage of 4.5 V. The generality of this approach was demonstrated by using it to coat LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> and lithium-rich layered oxides. This work provides a scalable and eco-friendly route for engineering grain boundaries and interfacial stability in high-energy cathode systems.