Unraveling the Effects of Al Doping on the Electrochemical Properties of LiNi_0.5Co_0.2Mn_0.3O₂Using First Principles

Abstract

One of the prevailing approaches to tune properties of materials is lattice doping with metal cations. Aluminum is a common choice, and numerous studies have demonstrated the ability of Al 3+ doping to stabilize different positive electrode materials, such as Li [Ni-Co-Mn] In recent decades, rechargeable batteries have demonstrated tremendous promise as alternate energy storage devices. In particular, Li-ion batteries (LIB) have revolutionized electronic devices, ranging from portable electronics to electric vehicles (EVs), due to their excellent power and energy density.1 The bottleneck of LIB in terms of capacity and performance is often considered to be the nature of the positive electrodes (cathodes).1-6 Among the cathode materials for LIB, layered transition metal (TM) oxides (LiTMO 2, TM = Ni, Co, Mn) are very promising candidates, and in particular LiCoO 2 . However, in spite of the commercialization and wide use of LiCoO 2 in portable LIB, it suffers from several drawbacks. Key disadvantages include high cost and safety concerns associated with cobalt.2-6 Other limitations of LiCoO 2 include low practical capacity (140 mAhg −1 ) and oxygen loss on charge. 7-10 Consequently, in a quest to move beyond LiCoO 2 , a new class of mixed transition metal oxides were designed, wherein Ni and Mn were introduced into the material (i.e. Li[Ni x Co y Mn z ]O 2 or simply NCM).11,12 The Ni-rich variants of these materials have emerged as the most promising low-cost and high capacity alternatives to the already mature LiCoO 2 . 10,13,14,11 These Nirich materials show improved performance; however, the capacities and stabilities are still too low for practical commercialization for EVs. 12Key hurdles in the commercialization of these materials for EV applications are associated with oxygen release at high voltages and cation migration, which leads to structural transformations. 15,16 Recently, it has been demonstrated that oxygen loss and cation migration are concurrent events. 16,17 To address these challenges, lattice doping of cations 18 has been adopted to improve the performance of these materials, and various cations were explored.18-24 A particularly promising dopant for these materials is Al, although its effect is still not fully understood. Early theoretical studies proposed that Al substitution in LiCoO 2 25 and NCMs 26 could increase the intercalation potential, and these predictions were verified experimentally. 27 Various studies reported beneficial effects of Al doping on LiCoO 2 and LiNiO 2 and NCMs. ), and found that Al doping reduces the reversible capacity, but significantly improves the thermal stability of the electrode in the de-intercalated state.36 Al doping in Li-rich-Mn-rich NCMs has also improved the thermal stabilities of these materials. 37 In a detailed theoretical study, Dianat et al. studied the effect of Al doping on Li-Mn-Ni-O based cathode materials.38 They reported that Al doping stabilizes the partially intercalated states, but increases the Li-diffusion barriers. Park et al. studie...

Understanding of performance degradation of LiNi0.80Co0.10Mn0.10O2 cathode material operating at high potentials

“…According to the above conclusions, research priority for solving the problems of NCM811 material should give to suppression of the oxygen evolution, followed by development of the anti-oxygen electrolytes that are chemically stable against the active oxygen evolution intermediates. In this regard, cationic doping has been proven to be particularly effective in stabilizing the lattice structure of layered transition metal oxides [48][49][50][51][52] , and nonflammable electrolytes would be a good option because of their ability in retarding the propagation of oxygen radicals [53,54] .…”

Predicting accurate cathode properties of layered oxide materials using the SCAN meta-GGA density functional

“…2 we observe that the in-Li-plane a parameter changes only slightly during delithiation, whereas the orthogonal vector, c, changes considerably, in line with previous studies on layered cathode materials. [14,21,24,39] Specifically, the a parameter decreases slightly on delithiation for LNO and LCO, while it increases for LMO. This effect may be attributed to differences in the structure of LMO (orthorhombic), and LNO and LCO (rhombohedral).…”

Recent Progress and Perspective of Advanced High‐Energy Co‐Less Ni‐Rich Cathodes for Li‐Ion Batteries: Yesterday, Today, and Tomorrow

“…Major and co‐workers elucidated the effects of Al doping on the electrochemical properties of the NCM system with the aid of theoretical predictions. [ 102 ] Considering all of the possible doping sites, the most energetically favorable structure was predicted to be stoichiometric Li[Ni 0.45 Co 0.2 Mn 0.3 Al 0.05 ]O 2 with Al substitution for Ni in each transition metal layer, as shown in Figure 14 a. The predicted formation energies of various compositions in the partially delithiated state suggested that Al‐doped NCM‐523 has a higher negative formation energy, which suggests a solid solution reaction.…”