Characterization of advanced electrode materials by means of ion - PowerPoint PPT Presentation

Characterization of advanced electrode materials by means of ion beam analysis technique for next generation Li-ion batteries Spanish leader Japanish leader Prof. J. Manuel Perlado Martin Prof. Yoshiaki Kato

Outline •Motivation. •Ion Beam Analysis Techniques for Li characterization. •Experimental results on Li distribution characterization in Li-ion batteries positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 secondary particles (1.0 ≤ x ≤ 0.5). •Experimental results on Li depth profiling in LiFeP. •Conclusions.

Motivation

Motivation • Li-ion batteries consist of a positive and a negative electrode separated by an electrolyte layer. When electrodes are linked by an external circuit, spontaneous electrochemical reactions, which involve Li diffusion, take place. • Therefore, the performance of a Li-ion battery (energy density, power, capacity, charge and discharge rates and lifetime) strongly depends, among other factors, on the characteristic of the electrodes and in particular on the Li diffusion capabilities on them. Further development of Li-ion batteries requires Li characterization.

Available techniques for Li ‐ ion batteries characterization

Li characterization Two remaining questions: •Can we measure the Li concentration? •If so, can we measure it during the charge-discharge processes?

Li characterization The Electrochemical Society Interface • Fall 2011 • TEM and EELS are techniques with surface sensitivity � ”can not be applied to real electrodes”. • No quantitative information

Charge and discharge processes Interest in the Li movement � Can we measuring the batteries microstructure and composition during the charge-discharge processes? YES, ….. BUT In-situ XRD diffraction of C- From XRD LiFe 0.6 Mn 0.4 PO 4 during the measurements only first charge-discharge cycle. information about the crystalline phases can be obtained � Is the Li always present in crystalline phases? Detailed structure of the XRD pattern during the first charging process.

Ion Beam Analysis tecniques (IBA) Analysis- magnet Iman ion MeV-Ion-Accelerator source conmutador Scattered Electrons RBS Ions NRA Nuclear reaction Ion lens Products PIGE γ - rays PIXE X-rays Target ERDA Recoil ions Courtesy of Dr. F. Munnik

IBA for Li characterization Characterize the Li distribution by means of • PIGE � spatial characterization • NRA � depth profiling Advantages: • Quantitative information about the elemental distribution. • Simultaneous measurement of different elements. • PIXE, PIGE and NRA spectra can be simultaneously measured. • The use of micro-beams allow good spatial resolution. • The use of external micro-beams allow measure large samples. • The use of NRA allow measuring the Li depth profiling without destroying samples.

IBA for Li characterization: necessity for cooperation SPAIN JAPAN CMAM/UAM TIARA/JAEA CNA/US 3/14/2013

Li distribution characterization in positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 secondary particles (1.0 ≤ x ≤ 0.5) Objectives • Characterize the elemental distribution in Li-ion battery positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 (1.0 ≤ x ≤ 0.5) microparticles: • As received (non-charged) • Charged • Study the dependence of the Li distribution on: • Electrode thickness. • Charging conditions. For these aims, cross-sectional samples need to be fabricated

Li distribution characterization in positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 secondary particles (1.0 ≤ x ≤ 0.5) As-received electrode • Li-rich and Li-depleted μ -particles � regions distribution. As-received individual microparticles K. Mima et al. NIMB 290 (2012) 79 • The Li distribution is homogeneous within the individual μ -particles. We thank the team of TOYOTA for supplying and preparation of the samples as well as, for the very nice cooperation.

Li distribution characterization in positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 secondary particles (1.0 ≤ x ≤ 0.5) One single measurements • gives information about the constituents of Active material: Ni, Co, • Al.. Binder: F, O, .. • Li yield is higher for the • uncharged than for the charged electrode. The Ni yield is the same in • both electrode. Li/Ni AR ~1.10 • K. Mima et al. NIMB 290 (2012) 79 Li/Ni Ch ~0.94 •

Li distribution characterization in positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 secondary particles (1.0 ≤ x ≤ 0.5) Thickness dependence: Th= 105 μ m Th d c t (min) ( μ m) (mA/c m 2 ) 35 2 15 105 6 15 Th= 35 μ m K. Mima et al. NIMB 290 (2012) 79 The Li distribution is more homogeneous for the thin than for the thick electrode.

Li distribution characterization in positive electrodes containing Li x Ni 0.8 Co 0.15 Al 0.05 O 2 secondary particles (1.0 ≤ x ≤ 0.5) Charge rate dependence: 6m A/cm 2 15 min. 0.6 mA/cm 2 150 min. K. Mima et al. NIMB 290 (2012) 79 Li inhomogeneously distributes in both electrodes • Fast charge → Homogeneous gradient in the Li distribution • Slow charge → Two regions with an abrupt boundary between them. •

CONCLUSIONS • μ -PIGE and μ -PIXE techniques are successfully applied to accurately measure the elemental (in particular Li) distribution in Li-ion batteries. • Li inhomogenously distributes in the electrode to the random distribution of the secondary particles. • The Li distribution within as-received individual secondary particles turns out to be homogeneous. • The Li distribution in the cross sections of the electrodes is observed to depend on electrode thickness and on charge conditions. • The Li distribution is: • Homogeneous in a thin electrode (35 μ m), • Inhomogeneous when increasing the thickness (105 μ m). • For the thick electrode (105 μ m) slow charge rate gives rise to a small gradient of the Li distribution in the electrode regions close to the Al current collector.

CONCLUSIONS Answer to questions: •Can we measure the Li concentration? •Yes, we can. •Can we measure it during the charge-discharge processes? •For the time being we have demonstrated that it can be measured in charged and uncharged batteries.

Manpower Prof. José Manuel Perlado Prof. Yoshiaki Kato (GPI) Prof. Emilio Minguez Prof. Kunioki Mima (GPI) Dr. Jesús Álvarez Prof. Sadao Nakai (GPI) Assoc. Prof. Emma del Río Assoc. Prof. Kazuhisa Fujita (GPI) Assoc. Prof. Raquel Gonzalez ‐ Prof. Yoshiharu Uchimoto (Kyoto Arrabal University) Assoc. Prof. Antonio Rivera Dr. Hirozumi Azuma (TCRL) Miguel Panizo Dr. Yoshio Ukyo (TCRL) Prof. Hiroaki Nishimura (ILE) Prof. Tomihiro Kamiya (TIARA)