Optimized Temperature Effect of Li‐Ion Diffusion with Layer Distance in Li(Ni_xMn_yCo_z)O₂ Cathode Materials for High Performance Li‐Ion Battery

Abstract

energy density, high voltage, and long cycle life. [ 2 ] As one of the most widely used cathode materials, LiNi x Mn y Co z O 2 (labeled as NMC) has been investigated extensively, due to their high reversible capacity, good environmental compatibility, and relatively high Li-ion diffusivity. In the previous works, different kinds of NMC materials with different content ratio of Ni, Co, and Mn have been developed, and their electrochemical properties have also been studied, such as Li(Ni 1/3 Mn 1/3 Co 1/3 ) O 2 (111), [ 3,4 ] Li(Ni 0.4 Mn 0.4 Co 0.2 )O 2 (442), [ 5 ] Li(Ni 0.42 Mn 0.42 Co 0.16 )O 2 (552), [ 6 ] Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 (532), [ 7 ] Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 (622), [ 8 ] and Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 (71515). [ 9 ] For example, Noh et al. compared the electrochemical properties including the Li-ion diffusion coeffi cient, capacity retention, and electrochemical stabilities (25 to 55 °C) of layered NMC cathode materials ((111), (532), (622), (71515), (811) and Li(Ni 0.85 Mn 0.075 Co 0.075 )O 2 ) at room temperature and found that the Ni content had a great infl uence on the electrochemical properties. [ 10 ] Solid phase diffusion coeffi cient ( D s ) is one of the most important parameters for the active materials of the LIBs, as it determines the charge and discharge rate capability directly. In particular, for high power density applications, fast Li-ion transport in cathode materials is a key factor and must be needed. As a result, many experimental and theoretical works have been devoted to investigating the Li-ion diffusion properties in layered cathode materials. [ 11,12 ] However, to the best of our knowledge, there is little work reported to study the relationship between the layer distance and kinetics of Li-ion diffusion in different temperatures of layered NMC cathode materials systematically, which is important for LIBs applied in multitemperature environments.At the same time, in order to measure D s accurately, many methods such as galvanostatic intermittent titration technique (GITT), [ 3,[13][14][15][16] potentiostatic intermittent titration technique (PITT), [ 14,17 ] electrochemical impedance spectroscopy, [ 18 ] and cyclic voltammetry [ 19 ] have been developed in the past decades. Although factors such as the inaccuracy of the assumptions, Understanding and optimizing the temperature effects of Li-ion diffusion by analyzing crystal structures of layered Li(Ni x Mn y Co z )O 2 (NMC) ( x + y + z = 1) materials is important to develop advanced rechargeable Li-ion batteries (LIBs) for multi-temperature applications with high power density. Combined with experiments and ab initio calculations, the layer distances and kinetics of Li-ion diffusion of LiNi x Mn y Co z O 2 (NMC) materials in different states of Li-ion de-intercalation and temperatures are investigatedsystematically. An improved model is also developed to reduce the system error of the "Galvanostatic Intermittent Titration Technique" with a correction of NMC particle size distribution. The Li-ion diff...

Chemical, Structural, and Electronic Aspects of Formation and Degradation Behavior on Different Length Scales of Ni‐Rich NCM and Li‐Rich HE‐NCM Cathode Materials in Li‐Ion Batteries

“…Li-rich HE-NCM CAMs can be seen as so-called "layered-layered" two-phase materials (it is an open discussion whether they should be described as single-phase solid solution or two-phase nanodomain materials), as they comprise a kind of composite of Li 2 MnO 3 [35][36][37][38][39] and LiTMO 2 (TM = Ni, Co, Mn), formally written as cLi 2 MnO 3 ⋅[1 − c]LiTMO 2 . Commonly used layered LiTMO 2 [109][110][111] and spinel LiTM 2 O 4 compounds (TM = Mn, Ni, and Co; Mg and/ or Al for stabilization) share a ccp oxygen framework (rhombohedrally distorted for LiTMO 2 ) with the same interlayer distance of about 4.7 Å. Li 2 TM′O 3 (TM′ = Mn, Ti, Zr) [112] as an electrochemically inactive compound also exhibits a ccp oxygen lattice with very similar lattice parameters but C2/m symmetry (Figure 2b).…”

Use of Ce to Reinforce the Interface of Ni‐Rich LiNi0.8Co0.1Mn0.1O2 Cathode Materials for Lithium‐Ion Batteries under High Operating Voltage

“…[20] In addition, Ni 2 + ions have al ow energy barriert om igrate into Li slabs because of their similar ionic radius to Li + ,w hichp romotes the transformation of the structure (layered!spinel!rock salt) at the surface. [26] Therefore, reinforcing the interface structure of Ni-rich cathodes is effective and crucial to suppressing transition-metal ions dissolution and cation disordering, and to further improvet he structural stability during charging/discharginga th igh operating voltage. [23][24][25] This kind of surface structure rearrangement of Ni-rich cathodes will destroy the active lithium intercalationl ocation in the lattice and slow down the interfacial charge-transferp rocess, thus decreasingt he capacity and lifespan.…”

“…[24] In addition, the phase transformation starting at the particle surfacew ill then gradually spread to the interior. [26] Therefore, reinforcing the interface structure of Ni-rich cathodes is effective and crucial to suppressing transition-metal ions dissolution and cation disordering, and to further improvet he structural stability during charging/discharginga th igh operating voltage. For many years, significant efforts have been devoted to improvingt he structural stability of Ni-rich materials by decreasing cationic mixinga nd inhibiting interfacial side reactions, such as lattice doping [27,28] and surfacer econstruction.…”

On the Ageing of High Energy Lithium-Ion Batteries—Comprehensive Electrochemical Diffusivity Studies of Harvested Nickel Manganese Cobalt Electrodes

“…However, a lack of knowledge regarding the impact of the characterisation technique and the influence of the ageing on the $L{i}^{+}$ diffusivity in Nickel Manganese Cobalt (NMC) electrodes still exists. It can be seen in the literature that experimental determinations of the $L{i}^{+}$ diffusion in the same material can often lead to values differing from several orders of magnitude [19,20,21,22,23,24]. …”