Efficient preservation of surface state of LiNi0·82Co0·15Al0·03O2 through assembly of hydride terminated polydimethylsiloxane

Surface engineering of nickel-rich materials can efficiently prevent the materials from adsorbing water and CO2 in the atmosphere to restrain the formation of the insulating Li2CO3 on the surface of the materials. Herein, we report a facile approach to preserve the surface state of LiNi0·82Co0·15Al0·03O2 via surface self-assembly of hydride terminated polydimethylsiloxane. The hydride terminated polydimethylsiloxane can be tightly linked to the hydroxyl groups on the surface of LiNi0·82Co0·15Al0·03O2 through hydrogen bonding likely as a monolayer, endowing the surface of the material with strong hydrophobicity. Consequently, the LiNi0·82Co0·15Al0·03O2 material modified with the siloxane polymer after stored for 14 days exhibits electrochemical performance similar to that of the fresh pristine counterpart, whereas the stored pristine sample shows severely deteriorated performance due to the formation of the thick Li2CO3 layer insulating to lithium ion transportation at the electrode/electrolyte interface. Furthermore, the similarity in the initial discharge capacity, cyclability and rate capability of the fresh pristine and siloxane polymer-modified samples demonstrates that differing from coating of most inorganic materials, the modified layer is favorable to the lithium ion transportation, probably due to rich oxygens in the backbone of the siloxane polymer.