Surface-Functionalized Coating for Lithium-Rich Cathode Material To Achieve Ultra-High Rate and Excellent Cycle Performance

Abstract

Although the lithium-rich cathode material Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 , as a promising cathode material, has a high specific capacity, it suffers from capacity decay and discharge voltage decay during cycling. In this work, the specific capacity and discharge voltage of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 are stabilized by surface-functionalized LiCeO 2 coating. We have conducted LiCeO 2 coating via a mild synchronous lithium strategy to protect the electrode surface from electrolyte attack. This optimized LiCeO 2 coating has high Li + conductivity and abundant oxygen vacancies. The results demonstrate that 3% LiCeO 2 -coated Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 exhibits the highest capacity retention rate at 1, 2, and 5 C after 200 cycles, which were 84.3%, 85.4%, and 86.3%, respectively. The discharge specific capacity was almost 1.3, 1.4, and 1.4 times that of the pristine electrode. In addition, the 3% LiCeO 2 electrode exhibited the least voltage decay of 0.409, 0.497, and 0.494 V at 1, 2, and 5 C, which was only about half of the pristine electrode. It should not be overlooked that the 3% LiCeO 2 electrode still exhibits a high capacity at high current densities of 1250 mA g −1 (5 C) and 2500 mA g −1 (10 C), and its specific discharge capacities are 190.5 and 160.6 mAh g −1 , respectively. These outstanding electrochemical properties benefit from surface-functionalized LiCeO 2 coatings. To better understand the mechanism of oxygen loss of lithium-rich materials, we propose the lattice oxygen migration path of the LiCeO 2 -coated electrodes during the cycle. Our research provides a possible solution to the poor rate capability and cycle performance of cathode materials through surfacefunctionalized coatings.

A Three in One Strategy to Achieve Zirconium Doping, Boron Doping, and Interfacial Coating for Stable LiNi0.8Co0.1Mn0.1O2 Cathode

“…All samples show high crystallinity with a rhombohedral crystal structure (R-3m space group), as well as no obvious impurity phases, and the clear peak splitting of (006)/(102) and (108)/(110) ( Figure 1b) indicate well-defined layered structure. [16] In addition, the (104) peak shifts to the right slightly with increasing ZrB 2 content in Figure 1c, while the (104) peak shifts to the left in the sample with only Zr doping according to the previous report. [17] This opposite result could be attributed to co-incorporation of the zirconium and boron into the NCM811 lattice.…”

A review on the stability and surface modification of layered transition-metal oxide cathodes

“…In the case of LMR cathodes, the irreversible release of lattice oxygen occurring with the extraction of Li ion during the first cycle at the surface inhibits the reversibility of the anionic redox (O 2À ? O nÀ ), which can also induce a large irreversible capacity loss and voltage decay [7,79] [157]. Moreover, LiCeO 2 -coated cathode exhibits lower irreversibility of oxygen loss as indicated by cyclic voltammetry curves, thus contributing to the stable cycling performance.…”

LiVOPO4‐Modified Lithium‐Rich Layered Composite Cathodes for High‐Performance Lithium‐Ion Batteries

“…Figure 1 exhibits the XRD patterns of bare LNCMO, LNCMO/4 %LVOP, and LNCMO/8 %LVOP powders. Clearly, the major diffraction peaks of all products can be indexed based on a hexagonal α‐NaFeO 2 structure with a space group of R‐3m [47–49] . Also, the weak superlattice peaks around 2θ=20–25° could be indexed based on a monoclinic Li 2 MnO 3 component with a C2/m space group, caused by the Li/Mn ordering in the transition metal layers [50–53] .…”