Electronic Structure and Comparative Properties of LiNixMnyCozO2 Cathode Materials

Sun, Hong; Zhao, Kejie

doi:10.1021/acs.jpcc.7b00810

Cited by 177 publications

(113 citation statements)

References 32 publications

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“…The Co L-edge NEXAFS spectrum further favors this ( Figure S2). The main edge energy value for Ni ions is associated with the 3+ oxidation state, which is characteristic of the NCM811 cathode material and reported by numerous authors [32][33][34]. This oxidation state of Ni ions is also evident from the Ni L-edge NEXAFS spectrum ( Figure S3).…”

Section: Resultssupporting

confidence: 69%

“…The presence of spectral features at an almost identical position ( Figure S4) and the lack of change of shape of spectra reveal that Mn ions exist in the same oxidation state during the charging and discharging process. These observations were also obtained from the XANES study of cathode materials during battery operation [32,33]. Figure 5b shows the Co L-edge spectra of NCM811 during charging and discharging.…”

Section: Resultssupporting

confidence: 54%

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Soft X-ray Absorption Spectroscopic Investigation of Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials

et al. 2020

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Herein, we report the soft X-ray absorption spectroscopic investigation for Li(Ni 0.8 Co 0.1 Mn 0.1 ) O 2 cathode material during charging and discharging. These measurements were carried out at the Mn L-, Co L-, and Ni L-edges during various stages of charging and discharging. Both the Mn and Co L-edge spectroscopic measurements reflect the invariance in the oxidation states of Mn and Co ions. The Ni L-edge measurements show the modification of the oxidation state of Ni ions during the charging and discharging process. These studies show that e g states are affected dominantly in the case of Ni ions during the charging and discharging process. The O K-edge measurements reflect modulation of metal-oxygen hybridization as envisaged from the area-ratio variation of spectral features corresponding to t 2g and e g states.Nanomaterials 2020, 10, 759 2 of 11 soft XAS measurements can give a complete account of underlying phenomena due to the orbital symmetry states in the oxide cathode material during charging and discharging. To depict these phenomena, the Ni-rich cathode material, Li(Ni 0.8 Co 0.1 Mn 0.1 )O 2 , is selected for the present investigation and denoted as NCM811. NCM811 is a well-known layered oxide cathode material and preferred for Li rechargeable batteries due to its high capacity [19,20]. Thus, this work investigates NCM811 cathode materials during charging and discharging using soft XAS. Experimental DetailsX-ray diffraction (XRD) experiments prior to electrochemical testing of cathode material were performed with the 9B high-resolution powder diffraction (HRPD) beamline of the Pohang accelerator laboratory (PAL) [21]. Pristine cathode material was also investigated using X-ray absorption near-edge spectroscopy (XANES) imaging measurements to reveal the local electronic structure. These measurements at the Mn K-, Co K-, and Ni K-edge were performed with the 7C X-ray nano imaging (XNI) beamline of the PAL. This beamline utilizes zone plate-based transmission X-ray nanoscopy, which is a kind of transmission X-ray microscopy (TXM), for image formation. A zone plate of diameter 150 µm and 40 nm outermost zone width was used for measurements. This arrangement gave a spatial resolution of 40 nm and a field of view (FOV) of around 50 µm. The X-ray absorption images based on TXM were captured at various energies within a 1 eV interval in the range −20 to 80 eV from the main edge energies of each respective element. The XANES spectrum was extracted from these X-ray absorption images [22].Soft XAS measurements of this cathode material at various charging and discharging states were performed with the 10D XAS-KIST beamline of the same laboratory in total electron yield (TEY) mode. The grating with 1100 grooves/mm was used to measure spectra at the Mn L-, Co L-, Ni L-, and O K-edges. The obtained spectra were background-subtracted and normalized with respect to the post-edge height [23]. Results and Discussion

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Section: Resultssupporting

confidence: 69%

Section: Resultssupporting

confidence: 54%

Soft X-ray Absorption Spectroscopic Investigation of Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials

et al. 2020

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“…An additional challenging topic for Li-ion batteries is that of replacing the cathode active materials, such as the already mentioned LiCoO2 and NMC. These layered oxides have been extensively studied in terms of electronic and structural properties 32 . However, they are approaching their intrinsic limit in terms of energy density with respect to the cathode mass; i.e., 550 Wh kg −1 and 800 Wh kg -1 respectively 33,34 .…”

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confidence: 99%

Challenges and perspectives for new material solutions in batteries

Pellegrini

Bodoardo

Brandell

et al. 2019

Solid State Communications

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We outline main challenges for future research in batteries, particularly, addressing the urgent needs of developing new environmentally friendly material solutions to enhance the energy density and safety of these storage devices. This will require embracing a multidisciplinary approach encompassing traditional electrochemistry and experimental solidstate physics, multiscale computational modelling, materials synthesis, and advanced characterization and testing Alessandro Volta was the first in 1796 to demonstrate a practical battery, the so called Voltaic pile, capable to exploit the energy delivered by spontaneous chemical redox reactions to produce electric power in a controlled fashion 1,2 . Batteries have evolved significantly since Volta's time, and

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“…The Co:Ni:Mn ratio can be tuned to optimize the mechanical and electrochemical performance while reducing cost. 6,7 Many NMC compositions preserve the same structure type, with some local Jahn-Teller distortions depending on the combination of oxidation states present in the mixed-metal system. 6,8 One key challenge for LIBs is to improve lifetimes and safety characteristics without compromising energy and power densities.…”

mentioning

confidence: 99%

“…6,7 Many NMC compositions preserve the same structure type, with some local Jahn-Teller distortions depending on the combination of oxidation states present in the mixed-metal system. 6,8 One key challenge for LIBs is to improve lifetimes and safety characteristics without compromising energy and power densities. 9,10 Thermal management is an important issue and is intimately connected to chemical degradation and battery lifetime.…”

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confidence: 99%

Highly Anisotropic Thermal Transport in LiCoO2

Yang¹,

Yang²,

Savory³

et al. 2019

Preprint

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<div>LiCoO2 is the prototype cathode in lithium ion batteries. It adopts a crystal structure with alternating Li+ and CoO2- layers along the hexagonal <0001> axis. It is well established that ionic and electronic conduction is highly anisotropic; however, little is known regarding heat transport. We analyse the phonon dispersion and lifetimes of LiCoO2 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 based on the phonon Boltzmann transport. The low thermal conductivity (< 10Wm-1K-1) originates from a combination of short phonon lifetimes associated with anharmonic interactions between the octahedral face-sharing CoO2- networks, as well as grain boundary scattering. The impact on heat management and thermal processes in lithium ion batteries based on layered positive electrodes is discussed.</div>

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Electronic Structure and Comparative Properties of LiNi_xMn_yCo_zO₂ Cathode Materials

Cited by 177 publications

References 32 publications

Soft X-ray Absorption Spectroscopic Investigation of Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials

Soft X-ray Absorption Spectroscopic Investigation of Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials

Challenges and perspectives for new material solutions in batteries

Highly Anisotropic Thermal Transport in LiCoO2

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