New Insights for the Abuse Tolerance Behavior of LiMn₂O₄ under High Cut‐Off Potential Conditions

Abstract

The further development of lithium-ion batteries is often desired to obtain higher capacities by charging to higher potentials. However, such a high potential (> 4.3 V) will inevitably result in capacity loss of the LiMn 2 O 4 cathode material over numerous cycles. In this work, degradation mechanisms of LiMn 2 O 4 electrode cycled at different charge cut-off potentials (4.4, 4.5, 4.6, 4.7, and 4.8 V vs. Li/Li + , respectively) have been investigated. It is found that the capacity degraded seriously after aging cycles at the cut-off potentials (< 4.6 V), especially at 4.4 V. Remarkably, a thicker cathode-electrolyte interface (CEI) film on the cathode surface can be observed when the potential reached 4.7 and 4.8 V. Thus, two degradation mechanisms are proposed, which are also verified by the calculation of the diffusion coefficient of Li + ions (D Li + ). This work demonstrates the relationship between the capacity fade and cut-off potentials and provides a useful guidance for other cathode materials with high-voltage operation.

Mn2+ or Mn3+? Investigating transition metal dissolution of manganese species in lithium ion battery electrolytes by capillary electrophoresis

“…Dissolution of manganese was observed for a variety of cathode materials [16, 17, 20, 21, 28–33]. In addition to dissolution mechanisms like corrosion or structural deformation, dissolution by disproportionation reaction of surficial Mn 3+ to Mn 4+ and soluble Mn 2+ is mainly reported in the literature [7, 17, 18, 20, 21, 29, 30, 34–36]. Several more recent studies found dissolved manganese to be mainly in oxidation state +3 not in +2, which is in contradiction to established reports.…”

High‐Voltage Nickel‐Rich NMC Cathode Material with Ionic‐Liquid‐Based Polymer Electrolytes for Rechargeable Lithium‐Metal Batteries

“…Recently, it is reported that the increasing cut-off potential results the higher Li + ion extraction from cathode. [12,13] Hence, further enhanced capacity of NMC can be obtained by increasing its upper cut-off potential. But at higher potential, the use of flammable liquid electrolyte arises the safety problem.…”

Anodic decomposition of surface films on high voltage spinel surfaces—Density function theory and experimental study

“…We focus on these organic fragments, and omit inorganic CEI components like LiF and Li w P x O y F z , related to PF − 6 decomposition. Such inorganic species are present [12][13][14]40,41 but neither release CO 2 gas nor have been predicted to be oxidized at any reasonable voltages. Indeed, PF − 6 decomposition products have been suggested to partially passivate LNMO.…”