scholarly journals Electrolyte reactivity at the charged Ni-rich cathode interface and degradation in Li-ion batteries

2021 ◽  
Author(s):  
Wesley M. Dose ◽  
Israel Temprano ◽  
Jennifer P. Allen ◽  
Erik Björklund ◽  
Christopher A. O’Keefe ◽  
...  
Keyword(s):  
Transition Metal ◽  
Chemical Oxidation ◽  
Lattice Oxygen ◽  
Electrochemical Reactions ◽  
Li Ion Batteries ◽  
Oxygen Release ◽  
Ni Content ◽  
Li Ion ◽  
Parasitic Currents ◽  
Interfacial Reactivity

The chemical and electrochemical reactions at the positive electrode-electrolyte interface in Li-ion batteries are hugely influential on cycle life and safety. Ni-rich layered transition metal oxides exhibit higher interfacial reactivity than their lower Ni-content analogues, reacting via poorly understood mechanisms. Here, we study the role of the electrolyte solvent, specifically cyclic ethylene carbonate (EC) and linear ethyl methyl carbonate (EMC), in determining the interfacial reactivity at LiNi0.33Mn0.33Co0.33O2 (NMC111) and LiNi0.8Mn0.1Co0.1O2 (NMC811). Parasitic currents are measured during high voltage holds in NMC/Li4Ti5O12 (LTO) cells, LTO avoiding parasitic currents related to anode-cathode reduction species cross-over, and are found to be higher for EC-containing vs. EC-free electrolytes with NMC811. No difference between electrolytes are observed with NMC111. On-line gas analysis reveals this to be related to lattice oxygen release, and accompanying electrolyte decomposition, which increases substantially with greater Ni content, and for EC-containing electrolytes with NMC811. This is corroborated by electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM) of NMC811 after the voltage hold, which show a higher interfacial impedance and a thicker oxygen-deficient rock-salt surface reconstruction layer, respectively. Combined findings from solution NMR, ICP (of electrolytes) and XPS analysis (of electrodes) reveal that higher lattice oxygen release from NMC811 in EC-containing electrolytes is coupled with more electrolyte breakdown and higher amounts of transition metal dissolution compared to EC-free electrolyte. Finally, new mechanistic insights for the chemical oxidation pathways of electrolyte solvents and, critically, the knock-on chemical and electrochemical reactions that further degrade the electrolyte and electrodes curtailing battery lifetime are provided.

Identifying the anionic redox activity in cation-disordered Li1.25Nb0.25Fe0.50O2/C oxide cathodes for Li-ion batteries

2020 ◽  
Vol 8 (10) ◽  
pp. 5115-5127 ◽  
Author(s):  
Mingzeng Luo ◽  
Shiyao Zheng ◽  
Jue Wu ◽  
Ke Zhou ◽  
Wenhua Zuo ◽  
...  
Keyword(s):  
High Capacity ◽  
Lattice Oxygen ◽  
Redox Activity ◽  
Li Ion Batteries ◽  
Oxygen Release ◽  
Oxide Cathodes ◽  
Li Ion ◽  
Oxygen Reaction

Reversible lattice oxygen reaction, and irreversible oxygen release are clarified in high capacity cation-disordered Li1.25Nb0.25Fe0.50O2/C cathode for Li-ion batteries.

Toward Establishing Electronic and Phononic Signatures of Reversible Lattice Oxygen Oxidation in Lithium Transition Metal Oxides For Li-Ion Batteries

2020 ◽  
Vol 32 (13) ◽  
pp. 5502-5514
Author(s):  
Nenian Charles ◽  
Yang Yu ◽  
Livia Giordano ◽  
Roland Jung ◽  
Filippo Maglia ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Lattice Oxygen ◽  
Li Ion Batteries ◽  
Li Ion ◽  
Oxygen Oxidation

scholarly journals Impact of Crystallography on Design of Cathode Materials for Li-ion Batteries

2014 ◽  
Vol 70 (a1) ◽  
pp. C20-C20
Author(s):  
Evgeny Antipov ◽  
Nellie Khasanova
Keyword(s):  
Transition Metal ◽  
Cathode Materials ◽  
Fossil Fuels ◽  
Negative Impact ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Li Ion Batteries ◽  
Practical Applications ◽  
Storage Devices ◽  
Li Ion

Ninety percent of the energy produced today come from fossil fuels, making dramatically negative impact on our future due to rapid consumption of these energy sources, ecological damage and climate change. This justifies development of the renewable energy sources and concurrently efficient large storage devices capable to replace fossil fuels. Li-ion batteries have originally been developed for portable electronic devices, but nowadays new application niches are envisaged in electric vehicles and stationary energy storages. However, to satisfy the needs of these rapidly growing applications, Li-ion batteries require further significant improvement of their properties: capacity and power, cyclability, safety and cost. Cathode is the key part of the Li-ion batteries largely determining their performance. Severe requirements are imposed on a cathode material, which should provide fast reversible intercalation of Li-ions at redox potential close to the upper boundary of electrolyte stability window, possess relatively low molecular weight and exhibit small volume variation upon changing Li-concentration. First generation of the cathode materials for the Li-ion batteries based on the spinel (LiM2O4, M – transition metal) or rock-salt derivatives (LiMO2) has already been widely commercialised. However, the potential to further improve the performance of these materials is almost exhausted. The compounds, containing lithium and transition metal cations together with different polyanions (XmOn)p- (X=B, P, S, Si), are now considered as the most promising cathode materials for the next generation of the Li-ion batteries. Covalently-bonded structural frameworks in these compounds offer long-term structural stability, which is essential for good cyclability and safety. Further advantages are expected from combining different anions (such as (XO4)p- and F- ) in the anion sublattice, with the hope to enhance the specific energy and power of these materials. Various fluoride-phosphates and fluoride-sulphates have been recently discovered, and some of them exhibit attractive electrochemical performance. An overview of the research on the cathode materials for the Li-ion batteries will be presented with special emphasis on crystallography as a guide towards improved properties important for practical applications.

Sign in / Sign up

Export Citation Format

Share Document