In Situ Raman Microscopy of Individual LiNi 0.8 Co 0.15 Al 0.05 O 2 Particles in a Li-Ion Battery Composite Cathode

Self Cite

Section: Resultssupporting

confidence: 93%

Diagnostic Evaluation of Detrimental Phenomena in High-Power Lithium-Ion Batteries

Kostecki

Lei

McLarnon

et al. 2006

Self Cite

“…1 Towards this end, much previous research focused on the development of LiNi 1-x Co x O 2 (NC) [2][3][4][5][6][7][8][9][10] cathode due to its high capacity (∼275 mAh/g) and favorable operating cell voltage (4.3 V vs. Li/Li + ), which is within the voltage stability window of current liquid electrolytes, and lower cost than LiCoO 2 . Despite extensive optimization, e.g., with respect to the Ni/Co ratio, 2-10 NC suffers from poor structural stability during electrochemical cycling.…”

mentioning

confidence: 99%

Characterization of Electronic and Ionic Transport in Li_1-_xNi_0.33Mn_0.33Co_0.33O₂(NMC₃₃₃) and Li_1-_xNi_0.50Mn_0.20Co_0.30O₂(NMC₅₂₃) as a Function of Li Content

Amin

Chiang

2016

209

133

Despite the extensive commercial use of Li 1-x Ni 1-y-z Mn z Co y O 2 (NMC) as the positive electrode in Li-ion batteries, and its long research history, its fundamental transport properties are poorly understood. These properties are crucial for designing high energy density and high power Li-ion batteries. Here, the transport properties of NMC 333 and NMC 523 are investigated using impedance spectroscopy and DC polarization and depolarization techniques. The electronic conductivity is found to increase with decreasing Li-content (increasing state-of-charge) from ∼10 −7 Scm −1 to ∼10 −2 Scm −1 over Li concentrations x = 0.00 to 0.75, corresponding to an upper charge voltage of 4.8 V with respect to Li/Li + . The lithium ion diffusivity is at least one order of magnitude lower, and decreases with increasing x to at x = ∼0.5. The ionic conductivity and diffusivity obtained from the two measurements techniques (EIS and DC) Cathodes having high energy and power density, adequate safety, excellent cycle life, and low cost are a critical need for Li-ion batteries to enable the commercialization of electric transportation and stationary storage.1 Towards this end, much previous research focused on the development of LiNi 1-x Co x O 2 (NC) 2-10 cathode due to its high capacity (∼275 mAh/g) and favorable operating cell voltage (4.3 V vs. Li/Li + ), which is within the voltage stability window of current liquid electrolytes, and lower cost than LiCoO 2 . Despite extensive optimization, e.g., with respect to the Ni/Co ratio, 2-10 NC suffers from poor structural stability during electrochemical cycling. 11Significant efforts were subsequently focused on improving structural stability and electrochemical performance by partial substitution Mn 12-17 (electrochemically inactive in this compound over the operating cell voltage window). Thus our objective in this work is to systematically characterize and interpret the transport properties of NMC 333 and NMC 523 . We use additive-free, single phase sintered samples in which the extrinsic effects due to binders, conductive additives, and particle microstructures that may be present in composite electrodes are avoided. Using electron blocking and ionic blocking cell configurations, respectively, and electrochemical impedance spectroscopy and DC polarization and depolarization techniques (see Table I), we deconvolute the electronic and ionic conductivities of NMC 333 and NMC 523 as a function of temperature and Li content, up to a lithium deficiency of x = 0.75, which corresponds to high charge voltages of 4.7 V and 4.8 V for NMC 333 and NMC 523 respectively. Our sample configuration permits measurement of single-phase properties up to delithiation levels (state-of-charge) where electrochemically-induced microfracture intrudes. Electronic conductivity was not apparently affected by these effects, whereas ionic transport shows an apparent increase beyond x = 0.50 which we attribute to fast transport paths created by microfracture. • C for 12 h in ambient atmosphere, preceded by h...

“…This intercalation material exhibits solid solution behavior during the extraction of lithium 3,4,18 and is structurally stable upon cycling. 2 The majority of studies of NCA have focused on structural and electrochemical characterization.…”

mentioning

confidence: 99%

Characterization of Electronic and Ionic Transport in Li_1-_xNi₀_.₈Co_0.15Al_0.05O₂(NCA)

Amin

Ravnsbæk

Chiang³

2015

Despite the extensive commercial use of Li 1-x Ni 0.8 Co 0.15 Al 0.05 O 2 (NCA) as the positive electrode in Li-ion batteries, and its long research history, its fundamental transport properties are poorly understood. These properties are crucial for designing high energy density and high power Li-ion batteries. Here, the transport properties of NCA are investigated using impedance spectroscopy and dc polarization and depolarization techniques. The electronic conductivity is found to increase with decreasing Li-content from ∼10 −4 Scm −1 to ∼10 −2 Scm −1 over x = 0.0 to 0.6, while lithium ion conductivity is at least five orders of magnitude lower for x = 0.0 to 0.75. A surprising result is that the lithium ionic diffusivity vs. x shows a v-shaped curve with a minimum at x = 0.5, while the unit cell parameters show the opposite trend. This suggests that cation ordering has greater influence on the composition dependence than the Li layer separation, unlike other layered oxides. From temperature-dependent measurements in electron-blocking cells, the activation energy for lithium ion conductivity (diffusivity) is found to be 1.25 eV (1.20 eV). Chemical diffusion during electrochemical use is limited by lithium transport, but is fast enough over the entire state-of-charge range to allow charge/discharge of micron-scale particles at practical C-rates. Cathodes having high energy and power density, adequate safety, excellent cycle life, and low cost are crucial for Li-ion batteries that can enable the commercialization of electric transportation.1 Towards this end, much research has previously focused on the development of the LiNi 1-x Co x O 2 (NC) 2-10 cathode due to its high capacity (∼275 mAh/g) and favorable operating cell voltage (4.3 V vs. Li/Li + ), which is within the voltage stability window of current liquid electrolytes. This compound also has lower cost than LiCoO 2 ; but despite extensive optimization, e.g., with respect to the Ni/Co ratio, 2-10 NC still suffers from poor structural stability during electrochemical cycling.11 Significant efforts were subsequently focused on improving structural stability by doping with small amounts of electrochemically inactive elements such as Al and Mg.12-17 One of the most promising compositions that emerged is Li 1 Ni 0.8 Co 0.15 Al 0.05 O 2 (NCA), currently in widespread commercial use. This intercalation material exhibits solid solution behavior during the extraction of lithium 3,4,18 and is structurally stable upon cycling. 2 The majority of studies of NCA have focused on structural and electrochemical characterization. Surprisingly, there is limited, and conflicting, data on the basic transport properties of the NC/NCA family of compounds. Thus our objective in this work is to systematically characterize and interpret the transport properties of NCA. We use additive-free, single phase sintered samples in which the extrinsic effects that may be present in composite electrodes are avoided. Using electron blocking and ion blocking cell configurations, respectively...