Abnormal phase-separated state of LixNi0.8Co0.15Al0.05O2 in the first charge: Effect of electrode compaction. (1st March 2018)

• Record Type: Journal Article
• Authors: Bobrikov, I.A.; Samoylova, N.Yu.; Ivanshina, O.Yu.; Vasin, R.N.; Sumnikov, S.V.; Kornieieva, K.A.; Balagurov, A.M.
• Is Part Of: Electrochimica acta. Volume 265(2018)
• Page Start: 726
• Page End: 735
• Publication Date: 2018-03-01
• Subjects: LiNi0.8Co0.15Al0.05O2 (NCA) -- Li-ion battery -- Neutron diffraction -- Phase separation -- First charge; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.01.200
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: A planar electrochemical cell developed for operando / in situ neutron diffraction experiments at time-of-flight diffractometers was used to study a structural state of Li x Ni0.8 Co0.15 Al0.05 O2 (NCA) electrodes with different degree of compaction. A two-phase-separated state of the NCA electrodes was observed in the first charge cycle. It was established that stronger compaction of the electrodes partially suppresses the phase separation of the cathode material: reduces a state of charge (SOC) range where two phases coexist, and decreases the difference between structural parameters of the phases. X-ray photoelectron spectroscopy has revealed a presence of Li2 CO3 film at the surface of the NCA material in the amount that is unlikely to affect the NCA behavior during the first charge. It was suggested that the phase-separated state is caused by the morphology of the NCA material. This observation could be expanded to layered cathode materials with similar microstructures. Graphical abstract: Image 1 Highlights: New electrochemical cell for TOF neutron diffraction experiments was developed. Two-phase separation of the NCA material during first charge is observed. Strong compaction of the electrodes reduces the phase separation of NCA. Phase separation of the NCA material during first charge is caused by its morphology. Simple model of phase separation of the NCA material during first charge is proposed.