Degradation of high-voltage cathodes for advanced lithium-ion batteries – differential capacity study on differently balanced cells

Abstract

The degradation of LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes were investigated using different cell designs (half cells, full cells cathode-limited, anode-limited and cathode-limited with pre-charge). Half cells based on Li/LNMO show long-cycle stability due to the unlimited source of electrochemically available lithium. Full-cell configurations with Li 4 Ti 5 O 12 /LNMO are limited in their cycling performance and durability. Differential capacity studies during continuous cycling reveal a systematic intensity change of the Ni II/III and Ni III/IV redox peaks as a function of the amount of electrochemically available lithium. As a mechanism, it could be clearly stated that the consumption of electrochemically available lithium determines the cycle stability. The decomposition of the active material itself (e.g. loss of Ni and Mn) is not crucial for the capacity loss. Thus, full cells with a pre-charged anode have the best cycling performance because of its high lithium content. ARTICLE HISTORY KEYWORDS High voltage; lithium-ion battery; lithium nickel manganese oxide; energy storage; lithium titanium oxide CLASSIFICATION 50 Energy Materials; 206 Energy conversion / transport / storage / recovery

Operando Raman Spectroscopy Measurements of a High-Voltage Cathode Material for Lithium-Ion Batteries

“…By comparing the observed degradation rate of the half-cells (this study) and full cells and considering the spectroscopic observation of electrolyte degradation products, the detection of Ni and Mn on the anode side (Supporting Information), and the fact that adding fresh electrolyte will temporally recover the cell (Supporting Information), one can conclude that there is (i) a decomposition of the cathode active material (LNMO) itself, leading to a deliberation of Ni and Mn, and (ii) oxidative/reductive decomposition of the liquid electrolyte by self-discharge, leading to a formation of Li-containing degradation products. The lithium ions in the degradation products are no longer available for charge transport (electrochemical availability).…”

Determining phase transitions of layered oxides via electrochemical and crystallographic analysis

“…LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC), as the most common representative, has already been studied extensively [3,4], including work aimed at improving the materials' properties by employing strategies such as doping and coating [5][6][7]. Among other cathode materials such as LiNi 0.5 Mn 1.5 O 4 (LNMO) spinels [8], NMC has already found its way into commercialization within the automotive sector, with Nissan being a prominent adopter of this material from the start.…”

Ti‐Based Reference Electrodes for Inline Implementation into Lithium‐Ion Pouch Cells

“…Differential capacities as a function of voltage were analyzed for full pouch cells at 0.2C cycling rate between 2.5 and 4.2 V. Figure 5 shows that the differential capacity curves can be used for battery ageing evaluation, given that separate anode and cathode values are obtained with the use of REs, enabling analysis of distinct potential curve features. [32][33][34][35][36] Here it can be observed that the intensity for both the cathode and anode decreases with increase in cycling from the 2nd to 70th cycles. The main feature of the overall cell, cathode, and anode with respect to RE monitoring is the loss of the dQ/dV initial peak 1, which shrinks its initial peak by %40-50%, and the inflexion point between peak 1 and 2 by %10%.…”