Highly Anisotropic Thermal Transport in LiCoO2

Hui Yang; Jia-Yue Yang; Christopher N Savory; Jonathan M Skelton; Benjamin J Morgan; David O Scanlon; Aron Walsh

doi:10.1021/acs.jpclett.9b02073

Highly Anisotropic Thermal Transport in LiCoO₂

J Phys Chem Lett. 2019 Sep 19;10(18):5552-5556. doi: 10.1021/acs.jpclett.9b02073. Epub 2019 Sep 5.

Authors

Hui Yang^{1

2}, Jia-Yue Yang³, Christopher N Savory^{4

2}, Jonathan M Skelton⁵, Benjamin J Morgan^{6

2}, David O Scanlon^{4

7

2}, Aron Walsh^{1

8

2}

Affiliations

¹ Department of Materials , Imperial College London , Exhibition Road , London SW7 2AZ , U.K.
² The Faraday Institution, Quad One, Harwell Science and Innovation Campus , Didcot OX11 0RA , U.K.
³ School of Energy and Power Engineering , Shandong University , Qingdao 266237 , China.
⁴ University College London , Department of Chemistry and Thomas Young Centre , 20 Gordon Street , London WC1H 0AJ , U.K.
⁵ School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , U.K.
⁶ Department of Chemistry , University of Bath , Claverton Down , Bath BA2 7AY , U.K.
⁷ Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 0DE , U.K.
⁸ Department of Materials Science and Engineering , Yonsei University , Seoul 03722 , Korea.

PMID: 31475830
DOI: 10.1021/acs.jpclett.9b02073

Abstract

LiCoO₂ is the prototypical cathode in lithium-ion batteries. Its crystal structure consists of Li⁺ and CoO₂^- layers that alternate along the hexagonal ⟨0001⟩ axis. It is well established that the ionic and electronic conduction are anisotropic, but little is known regarding the heat transport. We analyze the phonon dispersion and lifetimes using anharmonic lattice dynamics based on quantum-chemical force constants. Around room temperature, the thermal conductivity in the hexagonal ab plane of the layered cathode is ∼6 times higher than that along the c axis. An upper limit to the average thermal conductivity at T = 300 K of 38.5 W m^-1 K^-1 is set by short phonon lifetimes associated with anharmonic interactions within the octahedral face-sharing CoO₂^- network. Observations of conductivity <10 W m^-1 K^-1 can be understood by additional scattering channels including grain boundaries in polycrystalline samples. The impact on thermal processes in lithium-ion batteries is discussed.