A new method of pretreatment of lithium manganese spinels and high-rate electrochemical performance of Li[Li0.033Mn1.967]O4

Abstract

Lithium manganese spinels tend to aggregate upon annealing and do not allow for attaining high discharge rates when used as cathodes in lithium-ion batteries. To obtain spinel samples of lower aggregation and better highrate properties, precursors synthesized by means of a citric acid-aided route are suggested to be pyrolyzed in an inert atmosphere, instead of pyrolysis in air. The synthesis of nanosized Li[Li 0.033 Mn 1.967 ]O 4 is described, and its characteristics including X-ray diffraction, scanning electron microscopy, and porosity, as well as electrochemical test results are presented. The particle size of the materials obtained is smaller, the degree of aggregation is lower, and high-rate properties are better than for analogues pyrolyzed in air. In particular, sample Li||Li[Li 0.033 Mn 1.967 ]O 4 cells deliver *60 mAh g -1 at the current loads of 4,000 mA g -1

Mesoporous LixMn2O4Thin Film Cathodes for Lithium-Ion Pseudocapacitors

“…Galvanostatic cycling was also used to study capacity and capacity fade during repetitive charge–discharge cycles. Galvanostatic discharge curves (Figure a) show continuously sloping voltages during lithium intercalation and deintercalation rather than plateaus at distinct voltages, which occurs with bulk and larger crystallite systems. ,− These sloping voltage profiles are considered one of the hallmarks of pseudocapacitive behavior . At a rate of 50 C , this material stores approximately 0.3 mol of lithium per mole of Li x Mn 2 O 4 (1 < x < 2), corresponding to a capacity of around 44 mAh/g.…”

“…Currently, LiCoO 2 is the most widely used cathode material for lithium-ion batteries. Although LiCoO 2 along with other materials of the form LiMO 2 (where M is a transition metal) are layered and show good cycling stability in bulk, they do not show reliable cycling stability when nanostructured for fast lithium-ion intercalation. − One reason for this is that the insertion and removal of lithium ions results in a phase transition between trigonal and monoclinic lattice structures. − Aside from the lack of rapid diffusion kinetics, LiMO 2 materials are known to operate in the 3–4 V range versus lithium metal. , To increase this potential range above 4 V, while maintaining structural stability, one option appears to be the mixed-valent transition metal spinel LiMn 2 O 4 . − LiMn 2 O 4 shows activity in the 4–4.5 V range with reasonable structural robustness upon cycling. The structure contains lithium ions within tetrahedral sites that can be repeatedly inserted and removed while the structure remains in the tetragonal phase. ,− Because it does not contain a planar or linear channeled structure, however, fast ion intercalation is not observed in bulk versions of this material, but creating nanoscale versions of this material including nanocrystals and nanowires shows promise for improved kinetics. ,− One complication noted for LiMn 2 O 4 (LMO) is that discharge rates can be much higher than charge rates, and for many applications, it is fast charging that is key to expanded use. − For the work presented here, all charge and discharge rates are the same, so that materials with fast kinetics should be useful for both high output power and fast charging applications.…”

The effect of critical material prices on the competitiveness of clean energy technologies

“…LMO batteries are less often used alone, but can commonly be found in conjunction with NMC batteries to enhance the current required for acceleration, while the NMC portion of the battery gives the vehicle the sought after long range [39]. Compared to the traditional LCO batteries, LMO batteries are cheaper, have a high electrochemical potential, and contain less potentially harmful materials [40]. LCO batteries are used in electronics such as cell phones and laptops due to the very high specific energy, but the short lifespans, limited thermal stability, high price of cobalt, and low specific power make LCO less than ideal for electric vehicle applications [39].…”

Highly improved aqueous Zn‖LiMn2O4 hybrid-ion batteries using poly(ethylene glycol) and manganese sulfate as electrolyte additives

“…For the cell using conventional ZL as the electrolyte, the anodic peaks are located at 1.81 and 1.94 V, whereas the cathodic peaks appear at 1.79 and 1.92 V. When the electrolyte is replaced with ZL-8% PEG, the anodic peaks move to 1.80 and 1.96 V, while the cathodic peaks decrease to 1.66 and 1.84 V, resulting in larger polarization. 49 The increase in polarization is likely due to the fact that the addition of PEG increases the viscosity of the electrolyte, which suppresses the transport of Li ions. Furthermore, the anodic peak positions show almost no change, whereas the cathodic peak positions change significantly, indicating that the PEG-modified electrolyte has a greater impact on the insertion of Li ions than on their extraction.…”