Comparison of the so-called CGR and NCR cathodes in commercial lithium-ion batteries using in situ neutron powder diffraction

Abstract

The evolution of the 003 reflection of the layered Li(Ni,Co,Mn)O 2 (CGR) and Li(Ni,Co,Al)O 2 (NCR) cathodes in commercial 18650 lithium-ion batteries during charge/discharge were determined using in situ neutron powder diffraction. The 003 reflection is chosen as it is the stacking axis of the layered structure and shows the largest change during charge/discharge. The comparison between these two cathodes shows that the NCR cathode exhibits an unusual contraction near the charged state and during the potentiostatic step, where the potentiostatic step is recommended by the manufacturer. This feature is not shown to the same degree by the CGR cathode. The behavior is likely related to the compositions of these cathodes, the amount of Li/Ni site mixing and the presence of Al or Mn.

A comprehensive picture of the current rate dependence of the structural evolution of P2-Na2/3Fe2/3Mn1/3O2

“…43,44 In order to "tune" the c lattice parameter behaviour in layered lithium-ion battery cathodes, the compositions of cathodes have to be adjusted. Note, unlike the related O3 phase, 15 the c lattice parameter does not expand and then decrease within the charge step.…”

A Cylindrical Cell for Operando Neutron Diffraction of Li-Ion Battery Electrode Materials

“…Pursuing delithiation, the (003) diffraction line, as well as all other peaks with the l index dominating in their (hkl) Miller indices, shifts slightly back to higher 2θ angles, and the c cell parameter decreases, reaching 14.383(2) Å (d interslab ∼ 4.794 Å) for x Li ≈ 0.10(10) at 4.3 V vs. Li + /Li. This behavior has been reported for layered Li x NiO 2 (Li et al, 1993), Li x CoO 2 (Ohzuku and Ueda, 1994;Amatucci et al, 1996), and Li x (Ni,Co,Mn)O 2 materials (Alam et al, 2014;Ishidzu et al, 2016;Kondrakov et al, 2017b) and its origin is still under debate. A theoretical investigation of the LiCoO 2 phase diagram (Van der Ven et al, 1998) suggested that a strong overlap of the 2p orbitals of oxygen and the partially filled e g orbitals of the transition metal would lead to charge transfer, resulting in the depletion of the oxygen charge.…”

“…Commercial 18650-type batteries present excellent electrochemical performance, but the poor signal-to-noise ratio in the diffraction pattern, mainly because of the contributions from the hydrogenated electrolyte and separators, limits the structural information retrievable from Rietveld refinements. Moreover, it narrows the range of study to commercialized batteries, such as LiFePO 4 (Rodriguez et al, 2010;Sharma et al, 2010Sharma et al, , 2017, LiCoO 2 (Dolotko et al, 2012;Senyshyn et al, 2014), and LiNi 1/3 Mn 1/3 Co 1/3 O 2 (Alam et al, 2014;Dolotko et al, 2014;Taminato et al, 2016).…”

In Situ Powder Diffraction Studies of Electrode Materials in Rechargeable Batteries

“…[27] Additionally,recent work on commerciale lectrodes containing combinationso fM= NMC and with M = Ni, Co, and Al, showed interesting stacking axis behavior near the chargeds tate. [45] The LiNi 1/3 Co 1/3 Mn 1/3 O 2 (Panasonic CGR) cathodes showed an expansion of the c stacking axis that equilibrated near the charged state (and during the constant potential step often applieda t4 .2 V), whereas the Li(Ni,Co,Al)O 2 (Panasonic NCR) cathode showed an expansion of the c stacking axis until the charged state and then proceeded to contractd uring the constant potential step. During discharging the LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode contracted, whereas the Li(Ni,Co,Al)O 2 cathode initially expanded and then contracted.…”

“…During discharging the LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode contracted, whereas the Li(Ni,Co,Al)O 2 cathode initially expanded and then contracted. [45] Typically,t he Li(Ni,Co,Al)O 2 batteries were designed for high capacities with relatively low current applications,w hereas the LiNi 1/3 Co 1/3 Mn 1/3 O 2 batteries were designed for high rate charging/discharging with al ower capacity.A nother in situ NPD study comparedt he structural evolution of LiNi 0.5 Co 0.2 Mn 0.3 O 2 and LiCoO 2 during charging and contrasted their lattice parameter evolution. In this work, they observed ad ecrease in the c lattice parameter of LiNi 0.5 Co 0.2 Mn 0.3 O 2 near the charged state, whichw as directly attributedt ot he loss of cation mixing, that is, the partial occupation of Li on the Ni sites andv ice versa, which was found at lower states of charge.T his loss of cation mixing directly influenced the stacking axis (structural evolution) near the charged state of the battery.S uch ar ange of studies illustratet hat varying the chemicalc omposition of the electrode not only influences the electrochemical performance of the electrode, but also the structurale volution of the layered phases, especially close to the charged state.…”