The Effect of ZnO and MgO Coatings by a Sono-Chemical Method, on the Stability of LiMn_1.5Ni_0.5O₄as a Cathode Material for 5 V Li-Ion Batteries

Abstract

This work demonstrates the effect of coating LiMn 1.5 Ni 0.5 O 4 with MgO and ZnO by a sono-chemical method. It was found that the sonochemical process results in a coating that serves as a buffer, yet allows the easy transport of Li + ions to and from the active mass. Both the ZnO and MgO coatings modify the particles' surface chemistry and help to inhibit the dissolution of Mn and Ni ions from the active mass into the solution phase at elevated temperatures and thus managed to improve the stability of LiMn 1.5 Ni 0.5 O 4 as an high voltage cathode material. MgO was found to be more effective than ZnO in this regard. The MgO coated cathodes demonstrated better electrochemical performance than the uncoated material. Lastly, the ZnO-coated material indicated a reduction in thermal stability in standard solutions, while the MgO coating did not affect the material's thermal stability.

Advances in the Cathode Materials for Lithium Rechargeable Batteries

“…The degree of the dissolution of the Ni and Mn ions from LiNi 0.5 Mn 1.5 O 4 at elevated temperature is significantly decreased by the sacrificial reaction of MgO interacting with HF and PF 5 . [224] In addition, metal fluorides (e.g., AlF 3 ) as acoating material suppresses the growth of the SEI layer, and remains stable in HF-containing electrolyte thereby protecting the surface of the electrode. [230,231] Surface coating with Li compounds on the LNMO spinel stabilizes the interface between electrode and electrolyte by building am ore stable SEI layer on the electrode surface than on the un-coated one.F or example,t he Li 3 PO 4 -a nd Li 4 P 2 O 7coated LNMO exhibit improved cycle performance because the strong chemical bonding in P=Oc an resist the attack of oxidative or reductive compounds which come from the decomposition of the electrolyte at the high operating voltage.…”

Kathodenmaterialien für wiederaufladbare Lithiumbatterien

“…Um das Problem zu lösen, wurden verschiedene Arten von Beschichtungsmaterialien für Spinellmaterialien eingesetzt, z. B. Kohlenstoff, Metalle, Metalloxide oder Li‐Verbindungen . Im Allgemeinen ist der Zweck der Beschichtung, die Oberfläche des Kathodenmaterials vor Nebenreaktionen mit dem Elektrolyten zu schützen.…”

Lithium Polyacrylate (LiPAA) as an Advanced Binder and a Passivating Agent for High‐Voltage Li‐Ion Batteries

“…[ 43 ] Also, metal-oxide coating frequently leads to an increase in the impedance of the cathodes, which deteriorates their rate capability. [ 16 ] In turn, employing LiPAA as a cathode binder provides protection, passivation, and buffering in conjunction with excellent Li-ion transport. It is important to emphasize that the above fi ndings suggest that LiPAA can be used as a superb, multifunctional binder for all kinds of cathodes in Li-ion batteries.…”