Sublimated Se‐Induced Formation of Dual‐Conductive Surface Layers for High‐Performance Ni‐Rich Layered Cathodes

Abstract

Ni‐rich layered oxide cathode materials for Li‐ion batteries have received widespread attention owing to their high specific capacity and comparatively low cost. However, owing to Li‐containing surface residues, side reactions with the electrolyte and structural rearrangement after long‐term cycling leads to severe degradation of the cathode performance. Here, Se coating serves as a novel and simple sublimation‐inducing gas reaction method to modify the Ni‐rich layered material, resulting in capacity retention and rate performance improvement. The sublimed gaseous Se reacts with residual Li compounds to form a Li2SeO4 coating on the surface of the secondary particles, which simultaneously promotes the transmission of Li ions and reduces electrode‐electrolyte side reactions. Moreover, gaseous Se penetrates between the primary particles within the secondary particles to promote electron transmission. This dual‐conductive surface layer facilitates superior capacity and voltage retentions. Significantly, the proposed method is scalable and applicable to all Ni‐rich cathode materials.

The Cycle Stability and Rate Performance of LiNi0.8Mn0.1Co0.1O2 Enhanced by Mg Doping and LiFePO4 Coating

“…The surface content of Li 2 CO 3 reflects the degree of side reactions of the material. [37] The content of Mg 0.02 -NCM@20LFP is 28.88 %, which is significantly lower than 34.79 % of the NCM material. This indicates that the surface Li 2 CO 3 can be significantly reduced by modification, and the cyclic stability of the material can be effectively improved.…”

Transition Metal Vacancy in Layered Cathode Materials for Sodium‐Ion Batteries

“…From this aspect, surface modifications were taken into consideration. As a well‐known anti‐aging and oxygen‐radicals capturing element, Se was respectively introduced into LiCoO 2 , [98] NMC811 [99] and Li‐rich Mn‐based oxide [100] to catch the escaped oxygen to prevent it from attacking the electrolyte. Meanwhile, Se with weak electronegativity rearranged the electrons around lattice O and manipulate the molecular polarity within the structure, which benefit O 2 p −Mn 3 d hybridization and mitigate the lattice O loss.…”

Cobalt‐Free LiNiO2 with a Selenium Coating as a High‐Energy Layered Cathode Material for Lithium‐Ion Batteries

“…[ 37 ] Wu et al improved the cycling and rate performance of the cathode material by applying a sublimation‐induced gas reaction process to selenium‐coated LiNi 0.8 Co 0.1 Mn 0.1 O 2 . [ 38 ] However, direct selenium modification of Co‐free LiNiO 2 cathode materials has seldom been documented.…”