Minimized Metal Dissolution from High-Energy Nickel Cobalt Manganese Oxide Cathodes with Al₂O₃ Coating and Its Effects on Electrolyte Decomposition on Graphite Anodes

Abstract

High-energy nickel cobalt manganese oxides have been studied intensively as cathode materials for lithium-ion batteries. However, several hurdles need to be overcome to adopt these cathodes in commercial lithium-ion batteries. Herein, aluminum oxide (Al 2 O 3 ) coating was applied to high-energy nickel cobalt manganese oxides (HE-NCM, Li 1.33 Ni 0.27 Co 0.13 Mn 0.60 O 2+d ) by atomic layer deposition (ALD) and its effects on HE-NCM/graphite full cells were investigated. HE-NCM/graphite full cells have better cycling performance and efficiency when HE-NCM is coated with Al 2 O 3 . ICP-MS measurements show that the Al 2 O 3 coating can effectively prevent transition metal dissolution from HE-NCM. XPS and FT-IR analysis suggests that the surface film on HE-NCM cathodes does not change significantly with the Al 2 O 3 coating even after 50 cycles, however the surface film on graphite anodes shows a significant change. The resistance of graphite electrodes cycled with the uncoated HE-NCM is higher than that of graphite electrodes cycled with the Al 2 O 3 -coated HE-NCM due to the increased SEI thickness. The improved cycling performance of HE-NCM/graphite cells with Al 2 O 3 coating can be attributed to the minimized resistance increase on graphite as well as the suppression of cathode active material loss.

Identifying the Association between Surface Heterogeneity and Electrochemical Properties in Graphite

“…Impedance analyses using symmetric cells were performed to compare the SEI formation of six different graphites with 50% lithiation after the 1st, 11th, and 50th cycles ( Figure 6 a,b). The frequencies of semi-circle regions are over 100 Hz, indicating the resistance region attributed to the SEI [ 22 , 60 , 61 , 62 , 63 ]. Although there are differences among the samples, the SEI resistance generally increases as the cycle progresses.…”

“…For instance, the buildup in the 50th-SEI resistance is significantly larger than the 1st and 11th cycles, indicating the cell degradation. As cycles progress, the degradation accelerates, and the SEI resistance increases as more SEI layers become formed from the previously formed SEI [ 60 , 61 , 62 , 63 ]. Such catalyzed degradation looks more pronounced with a higher content of non-basal sites and pores, which means that the SEI formation can occur continuously at the pore and non-basal sites ( Figure S7 ).…”

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

“…Surface coating can inhibit unexpected reactions at the interface between material and electrolyte in effect, and increase the structural stability of the surface and interface, thereby improving the capacity retention rate and safety of materials, for instance, WO 3 , [24] TiO 2 , [25] Al 2 O 3 , [26] and ZrO 2 [27] . Although non‐electroactive coatings can serve the above purpose, their inertia reduces the lithium‐ion mobility of the material.…”

“…In addition, after deep delithiation, Mg 2 + can serve as a "pillar" of the transition metal layer, reducing the repulsion between O 2À À O 2À and improving the bond energy of OÀ MÀ O, effectively preventing structural collapse and improving material cycle stability due to lattice shrinkage. [23] Surface coating can inhibit unexpected reactions at the interface between material and electrolyte in effect, and increase the structural stability of the surface and interface, thereby improving the capacity retention rate and safety of materials, for instance, WO 3 , [24] TiO 2 , [25] Al 2 O 3 , [26] and ZrO 2 . [27] Although non-electroactive coatings can serve the above purpose, their inertia reduces the lithium-ion mobility of the material.…”

Controllable atomic layer deposition coatings to boost the performance of LiMnxCoyNi1−x−yO2 in lithium-ion batteries: A review

“…Coating approach contributes to suppressing the occurrence of side reactions and accelerating the transport of lithium ions [11,12,13,14,15], whereas doping approach contributes to stabilizing the crystal structure and improving the reaction kinetics [16,17,18,19,20]. To obtain an excellent coating structure, various preparation methods have been developed, including high temperature sintering [21], sol-gel method [22], chemical vapor deposition (CVD) [23], liquid phase [24], hydrothermal [25] and solvothermal method [26], atomic layer deposition (ALD) [27], and solution-based precipitation [28]. Indeed, a large number of coating materials have been used, including metals (e.g., Ag [29]), metal oxides (e.g., Al 2 O 3 [30], SnO 2 [31], ZrO 2 [32], MnO 2 [33], Fe 2 O 3 [34], MgO [35], and ZnO [5]), fluorides (BiOF [36] and AlF 3 [37]), metal phosphates (Li 3 PO 4 [38], FePO 4 [39], AlPO 4 [40], and Li 4 P 2 O 7 [41]), and carbon, among others [42,43,44].…”