Delithiation Process Research Articles

Preparation and electrochemical properties of porous SiO/Ni anode materials for lithium-silicon batteries

To alleviate the volume expansion and improve the electrical conductivity of silicon monoxide (SiO) anode materials for lithium-silicon batteries, porous SiO (P-SiO) was prepared by silver-assisted chemical etching, and then porous SiO/Ni (P-SiO/Ni) composites were prepared by electroless Ni plating. The effect of SiO particle size on the microstructure of P-SiO and its electrochemical properties and the effect of Ni+ concentration in the plating solution on the microstructure of P-SiO/Ni and its electrochemical properties were systematically investigated, and the process mechanism of the preparation porous SiO by silver assisted chemical etching was firstly clarified. The results show that both the refinement and porosity of the SiO raw material are beneficial to alleviate the volume expansion of the P-SiO electrodes during the lithiation and delithiation process, and thus improve their the electrochemical performance. The electroless plating of nickel on the surface of P-SiO is also beneficial to further alleviate the volume expansion and increase the electrical conductivity of P-SiO electrode, thus further improving its specific capacity and cycling stability, the P-SiO/Ni anode with 3.03 wt% Ni content prepared at the Ni2+ concentration of 13 g/L has the best electrochemical performance, which the first discharge specific capacity reaches 1725.67 mAh/g, the first coulomb efficiency reaches 69.53%, and the reversible specific capacity after 200 cycles reaches 811.34 mAh/g at 1 A g−1 with a capacity retention rate of 62.39%.

Delithiation dynamics of the LICGC electrolyte out of the voltage limits

The recently developed concept of an all-solid-state Li battery is deemed by many as a breakthrough toward safer and higher-capacity rechargeable devices. This, in turn, motivates the researchers in pushing all the battery components up to and beyond operational limits to test the materials’ performance. Herein we present an in-situ characterization of the response of the Lithium Conductive Glass-Ceramic (LICGC) solid electrolyte to the application of a cycling voltage, extending the operating limits up to ±15 V. The purpose was to clarify the dynamics of the delithiation process out of the standard conditions. The Atomic Force Microscopy (AFM) has been employed to monitor the evolution of the LICGC surface morphology induced by high voltage. The in-situ measurement showed that the delithiation of LICGC (encompassed with thin metallic current collectors) leads to the out-diffusion of Li through defects in the current collectors, and the formation of the Li-based nanoparticles (NPs) on the sample surface. The growth of NPs and the formation of nano-to-macro clusters is dependent on the applied voltage: the higher the voltage the larger the NPs. The AFM results are supported by the Neutron Depth Profiling data, which confirm high concentrations of Li in NPs, and by X-rays photoelectron spectroscopy, which clarifies the composition of NPs.

Improving Fundamental Understanding of Si-Based Anodes Using Carboxymethyl Cellulose (CMC) and Styrene-Butadiene Rubber (SBR) Binder for High Energy Lithium Ion Battery Applications

With increasing demand of high energy density lithium ion batteries, silicon (Si) based anodes are an obvious substitute of graphite based systems due to their high capacity. However, large volume changes of Si during lithiation and delithiation processes causes pulverization of silicon particles. The resulting reduction in electrical continuity and solid electrolyte interphase (SEI) growth within the anode leads to a fast depletion of lithium reservoirs and an accelerates battery failure. High energy lithium ion battery applications such as electrical vehicles and electronic devices require high capacity retention over extended cycling, so improving performance of Si-based anodes is a critical need for many applications.Commonly, a combination of sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) is used as a binder for waterborne Si anode slurries. In these systems, carboxyl (-COOH) groups on CMC form chemical bonding with hydroxyl (-OH) groups on Si active material surface and SBR addition provides enhanced flexibility in the anode layer. Several reports on electrode integrity improvement through adhesion promoters, increased crosslinking, different binding groups, etc. are available in the literature. Delving deeper into the weak mechanical integrity of Si based anodes, and understanding the parameters influencing the fabrication process and subsequent properties, is important. This presentation will focus on several variations in Si based anode slurries and electrodes using CMC-SBR binders. Physical, mechanical, and electrochemical properties are extensively studied as a function of these parameters and will be discussed.

A Numerical Study of Mechanical Degradation of Carbon-Coated Graphite Active Particles in Li-ion Battery Anodes

During operation, different diffusive and mechanical phenomena take place inside LIBs that result in a loss of performance and, eventually, threaten battery life. One of the main drawbacks affecting anode materials is the significant volumetric expansion (contraction) experienced by active material particles during lithiation (delithiation) processes, which may cause fracture. In this work, we present a novel numerical model to analyze coupled diffusion-mechanical problems accounting for material inhomogeneities. We are able to describe the nucleation of cracks and their propagation during particle cycling, depending on charging and discharging rates. Moreover, our model is able to reproduce complex fracture processes such as branching and change of directions. This description relies on combined use of a randomness parameter and a stochastic characterization of material properties within a lattice model approach. The model is used to analyze the effect of particle coating as a strategy to diminish the effect of transient cracking (that leads to early capacity fade). This is studied in detail at the coating-substrate interface and novel material designs are tested within our simulation framework.

Li8MnO6: A Novel Cathode Material with Only Anionic Redox.

In Li-excess transition metal-oxide cathode materials, anionic oxygen redox can offer high capacity and high voltages, although peroxo and superoxo species may cause oxygen loss, poor cycling performance, and capacity fading. Previous work showed that undesirable formation of peroxide and superoxide bonds was controlled to some extent by Mn substitution, and the present work uses density functional calculations to examine the reasons for this by studying the anionic redox mechanism in Li8MnO6. This material is obtained by substituting Mn for Sn in Li8SnO6 or for Zr in Li8ZrO6, and we also compare this to previous work on those materials. The calculations predict that Li8MnO6 is stable at room temperature (with a band gap of 3.19 eV as calculated by HSE06 and 1.82 eV as calculated with the less reliable PBE+U), and they elucidate the chemical and structural effects involved in the inhibition of oxygen release in this cathode. Throughout the whole delithiation process, only O2- ions are oxidized. The directional Mn-O bonds formed from unfilled 3d orbitals effectively inhibit the formation of O-O bonds, and the layered structure is maintained even after removing 3 Li per Li8MnO6 formula unit. The calculated average voltage for removal of 3 Li is 3.69 V by HSE06, and the corresponding capacity is 389 mAh/g. The high voltage of oxygen anionic redox and the high capacity result in a high energy density of 1436 Wh/kg. The Li-ion diffusion barrier for the dominant interlayer diffusion path along the c axis is 0.57 eV by PBE+U. These results help us to understand the oxygen redox mechanism in a new lithium-rich Li8MnO6 cathode material and contribute to the design of high-energy density lithium-ion battery cathode materials with favorable electrochemical properties based on anionic oxygen redox.

Suppress oxygen evolution of lithium-rich manganese-based cathode materials via an integrated strategy

Improving the reversibility of anionic redox and inhibiting irreversible oxygen evolution are the main challenges in the application of high reversible capacity Li-rich Mn-based cathode materials. A facile synchronous lithiation strategy combining the advantages of yttrium doping and LiYO2 surface coating is proposed. Yttrium doping effectively suppresses the oxygen evolution during the delithiation process by increasing the energy barrier of oxygen evolution reaction through strong Y–O bond energy. LiYO2 nanocoating has the function of structural constraint and protection, that protecting the lattice oxygen exposed to the surface, thus avoiding irreversible oxidation. As an Li+ conductor, LiYO2 nanocoating can provide a fast Li+ transfer channel, which enables the sample to have excellent rate performance. The synergistic effect of Y doping and nano-LiYO2 coating integration suppresses the oxygen release from the surface, accelerates the diffusion of Li+ from electrolyte to electrode and decreases the interfacial side reactions, enabling the lithium ion batteries to obtain good electrochemical performance. The lithium-ion full cell employing the Y-1 sample (cathode) and commercial graphite (anode) exhibit an excellent specific energy density of 442.9 Wh kg−1 at a current density of 0.1C, with very stable safety performance, which can be used in a wide temperature range (60 to −15 °C) stable operation. This result illustrates a new integration strategy for advanced cathode materials to achieve high specific energy density.

Lanthanum Oxyfluoride modifications boost the electrochemical performance of Nickel-rich cathode

Lanthanum oxyfluoride (LaOF) materials have appreciable higher conductivity, favorable thermal and chemical stability, herein the LaOF coating layer was synthesized on the cathode LiNi0.8Co0.1Mn0.1O2 through one-step solid-phase method, to study the effect of LaOF modification of the electrochemical performance. The modified sample 0.4LaOF-NCM exhibits the initial discharge capacity of 182.8 mAh·g−1 and the retention of 87.8% after 300 cycles at 1C and 2.8–4.3 V (half-cell, room temperature); meanwhile, its full cell has the capacity of 179.8 mAh·g−1 and the retention of 83.5% after 300 cycles, superior to the pristine NCM (175.8 mAh·g−1 and 79%, full cell). Through analyses of XRD, SEM, HRTEM and XPS test results, it indicates that the LaOF amorphous coating layer on the surface of the NCM material can inhibit the side reactions between the cathode and the electrolyte during the cycling, and consequently improve the cycling stability. After 100th cycles, the Li+ diffusion rate during the delithiation and lithiation process is 1.63 × 10−10 and 1.02 × 10−10 cm2 s−1 for the pristine NCM, whereas for the 0.4LaOF-NCM the Li+ diffusion rate is respectively 2.08 × 10−10 and 1.45 × 10−10 cm2 s−1, which are more than 1.3 times faster than those of the pristine NCM. It is suggested that such LaOF modification would have promising applications to improve the performance of LIB.

Plastic dissipation of high-capacity electrode materials during lithiation and de-lithiation processes

Plastic dissipation of high-capacity electrode materials during lithiation and de-lithiation processes

Sustainable LiCoO2 by collective glide of CoO6 slabs upon charge/discharge

SignificanceTraditional views indicate that the well-known layered LiCoO2 cathode delivers a typical solid-solution reaction upon delithiation. The problem is that "solid solution" is a vague concept, and the phase transition remains ambiguous. Here, we reveal a mechanism with the collective and quasi-continuous glide of CoO6 slabs in layered LiCoO2 through combiningin situ XRD and ex situ STEM characterizations. Such a delithiation mechanism does not involve the nucleation-and-growth-type delithiation process and represents a completely different manner from the conventional two-phase or solid solution-phase transition processes. The lessons provide a different insight into understanding the working mechanism of layered oxide materials.

Charge Compensation Mechanisms and Oxygen Vacancy Formations in LiNi1/3Co1/3Mn1/3O2: First-Principles Calculations.

Charge compensation mechanisms in the delithiation processes of LiNi1/3Co1/3Mn1/3O2 (NCM111) are compared in detail by the first-principles calculations with GGA and GGA+U methods under different U values reported in the literature. The calculations suggested that different sets of U values lead to different charge compensation mechanisms in the delithiation process. Co3+/Co4+ couples were shown to dominate the redox reaction for 1 ≥ x ≥ 2/3 by using the GGA+U1 method (U1 = 6.0 3.4 3.9 for Ni, Co, and Mn, respectively). However, by using the GGA+U2 (U2 = 6.0 5.5 4.2) method, the results indicated that the redox reaction of Ni2+/Ni3+ took place in the range of 1 ≥ x ≥ 2/3. Therefore, according to our study, experimental charge compensation processes during delithiation are of great importance to evaluate the theoretical calculations. The results also indicated that all the GGA+Ui (i = 1, 2, 3) schemes predicted better voltage platforms than the GGA method. The oxygen anionic redox reactions during delithiation are also compared with GGA+U calculations under different U values. The electronic density of states and magnetic moments of transition metals have been employed to illustrate the redox reactions during the lithium extractions in NCM111. We have also investigated the formation energies of an oxygen vacancy in NCM111 under different values of U, which is important in understanding the possible occurrence of oxygen release. The formation energy of an O vacancy is essentially dependent on the experimental conditions. As expected, the decreased temperature and increased oxygen partial pressure can suppress the formation of the oxygen vacancy. The calculations can help improve the stability of the lattice oxygen.

Hierarchical nanospheres of Fe2O3-Fe2N anchored on reduced graphene oxide as a high-performance anode for lithium-ion batteries

The development of cost-effective and promising anode material is an ever-growing demand of the energy storage research community. Here we report a hierarchically nanostructured lithium-ion storage anode developed by partial nitridation of Fe2O3 nanospheres anchored on reduced graphene oxide sheets (Fe2O3-Fe2N/rGO). The incorporation of electron-rich N-moiety profoundly stabilizes Fe2O3 during the delithiation process. The graphene network not only serves as a nucleation substrate for suppressing agglomeration of Fe2O3-Fe2N but also provides a large surface area, high electrical conductivity, faster ionic diffusion kinetics and maintains structural integrity while absorbing high strain. The structure, morphology and composition analysis validated the successful development of the targeted material. The enhanced structural attributes ensure the effectiveness of Fe2O3-Fe2N/rGO as high-performance anode material with an initial discharge capacity of 1565 mAh g‒1 at 50 mA g‒1 and capacity retention of 759 mAh g‒1 after 500 cycles reflecting superior cycling stability and rate performance.

Reversible lithium insertion and conversion process of amorphous VS4 revealed by operando electrochemical NMR spectroscopy

Due to the high theoretical capacity, VS4 is a promising electrode material for next-generation rechargeable batteries. In this study, the lithium insertion and conversion process of amorphous VS4 was investigated using operando electrochemical nuclear magnetic resonance (NMR) spectroscopy. Amorphous VS4 has a chain-like structure similar to that of crystalline VS4. The chain structure was drastically changed to the [VS4]3− tetrahedral structure by lithium insertion up to the Li3VS4 composition. The lithium insertion into the [VS4]3−-based structure proceeded further up to the Li6VS4 composition, with charge compensation by the reduction of the V valency. Finally, the conversion reaction from amorphous Li6VS4 to metallic V and 4Li2S was observed. The structural reversibility of amorphous VS4 was confirmed after the delithiation. It is worth mentioning that the delithiation process from the conversion products was different from the lithiation, resulting in a relatively large voltage hysteresis. Broadly, this study demonstrates that the operando electrochemical NMR technique is a useful tool for investigating the complex reaction system of non-crystalline battery materials.

Colloidal polypyrrole as binder for silicon anode in lithium ion batteries

AbstractSilicon (Si)‐based anodes have limited application in lithium ion batteries (LIBs) due to the loss of contact with current collector because of large volume change during lithiation and delithiation processes. In this study, pyrrole (Py) was polymerized chemically by cerium ammonium nitrate (CAN) and conductive colloidal polypyrrole (Col‐PPy) was obtained in one step in N,N′‐dimethylformamide (DMF). To overcome problems during the volume change, Col‐PPy was then used as polymeric binder with Si nanoparticle (SiNP) in Si‐anode and it called as “Col‐PPy/SiNP.” In order to improve the cyclability and capacity of Si‐anodes, Col‐PPy solution was used also together with polyvinylidenefluoride (PVDF) and polyvinylpyrrolidone (PVP). These Si‐anodes were further analyzed with cycle tests and combined cycle tests at different rates (C‐rate) in half cells and scanning electron microscopy images of electrodes were taken before and after cycling. All results suggested that as an anode for LIB, Col‐PPy/SiNP exhibited high reversible capacity (2617 mAh/g at C/10 [0.42 A/g]) and good cycling performance (reversible capacity of 1400 mAh/g after 189 cycles at C/3 [1.4 A/g]).

Co-Inlaid Carbon-Encapsulated SiOx Anodes via a Self-Assembly Strategy for Highly Stable Lithium Storage.

SiOx is a promising anode material for next-generation lithium-ion batteries, with high energy density and low cost. However, several issues, such as poor cycling stability, should be overcome before practical application. Here, gum arabic, a well-known natural gum with low cost, is used as a carbon source to form a uniform Co-inlaid carbon coating on SiOx by a facile and scalable self-assembly method using Co2+ as a "bridge", during which Co2+ plays a key role. After carbonization treatment, the Co-inlaid carbon coating can effectively mitigate volume effects, enhance electrical conductivity, boost deep delithiation processes, and guarantee the structural integrity of SiOx-Co@C. Because of the unique Co-inlaid carbon coating, the SiOx-Co@C electrode displays much improved lithium-storage properties. The charging capacity of the SiOx-Co@C electrode at the 250th cycle is 1010.8 mA h g-1 with 84% capacity retention at 200 mA g-1. This work presents a facile and efficient strategy to construct a uniform multifunctional coating for improved electrochemical properties.

Bi Works as a Li Reservoir for Promoting the Fast‐Charging Performance of Phosphorus Anode for Li‐Ion Batteries

AbstractPhosphorus anodes are a promising for fast‐charging high‐energy lithium‐ion batteries because of their high specific capacity (2596 mAh g–1) and suitable lithiation potential (0.7 V vs Li+/Li). To solve the large volumetric change and inherent poor electrical conductivity, various carbon‐based materials have been studied for loading P. However, the local aggregation of Li ions and electrons in P particles especially in the fast‐charging process induces an uneven lithiation reaction and the great transient stress, leading to poor fast‐charging performance. Herein, bismuth nanoparticles are implanted into a P/graphite (P/C) composite using ball milling. The Bi anode works as a small Li reservoir for trapping Li in the lithiation process and emitting Li in delithiation process prior to P anode, because the Bi anode has a starting lithiation/delithiation potential that is a little bit higher/lower than the P anode. Moreover, the low Li diffusion barrier in Bi and the stable interface between Bi and P enhance the Li reservoir effect of Bi, which promotes fast and uniform lithiation/delithiation reactions and avoids continuous cracking of the Bi‐P/C electrode. Therefore, the Bi‐P/C anode provides a high fast‐charging capacity of 1755.7 mAh g–1 at 7.8 A g–1 (5.2 C) and a high capacity retention of 86.3% after 300 cycles.

Microstructure dependent chemo-mechanical behavior of amorphous Si anodes for Li-ion batteries upon delithiation

Alloying-type anodes exhibit the solid-state amorphization during charging/discharging cycles. The mechanical and electrochemical properties of amorphous reaction phases have been widely explored recently. However, there is still lack of understanding of the underlying mircostructure-property relation in the delithiation behavior of alloying anodes. Here we perform molecular dynamics simulations to investigate the microstructure effect on the chemo-mechanical properties of amorphous Si ( a -Si) anodes upon delithiation. It is indicated that stress-free delithiation without sufficient structural relaxation leads to the gradual accumulation of structural disorder (the increase of excess energy) in amorphous Li-Si systems ( a -Li x Si). The creation of structural disorder during delithiation not only facilitates the plastic deformation of a -Li x Si at lower stress, but also thermodynamically destabilizes a -Li x Si associated with the drop of open-cell potentials. While upon constrained delithiation, the initial value of excess energy and reaction stress both contribute to the increase of structural disorder during delithiation process. Based on the stress-dependent chemical-potential model, the tensile stress increases open-cell potentials, and reduces the Li chemical potential which weakens the driving force for delithiation. As a result, the structural disorder and tensile reaction stress may cause the undesirable capacity fading of a -Si anodes, and is detrimental to the battery performance. • The delithiation behavior of amorphous Si anodes is simulated by MD simulations. • The structural disorder in amorphous Si is quantified by excess energy. • The effect of structural disorder on the chemo-mechanical properties is explored.

Controlled Synthesis of Highly Active Nonstoichiometric Tin Phosphide/Carbon Composites for Electrocatalysis and Electrochemical Energy Storage Applications

Three types of new-structured phosphorized tin microspheres (Sn–P), phosphorized tin microsphere-carbon (Sn–P–C), and phosphorized tin nanoparticles embedded in interconnected porous carbon microspheres (Sn–P@PCMs) were prepared through a carbothermal reduction-assisted phosphorization strategy. The characterization of the formation mechanism and microstructure of Sn–P, Sn–P–C, and Sn–P@PCMs composites demonstrated that the controllable evaporation of coordinated phosphorus in the thermally unstable tin phosphide intermediate by accurate thermal treatment contributed to the formation of a ca. 3 wt % P-doped metallic tin structure featuring a nonstoichiometric SnxPy (y/x = 0.2) core, a Sn-rich phosphorized metallic (y/x = 0.05) shell, and an increased phosphorus concentration from the outer surface to the inner core. The as-prepared phosphorized tin-based composites were applied as counter electrode materials for dye-sensitized solar cells (DSSCs), in which the Sn–P–C counter electrode exhibited the lowest charge transfer resistance of 3.47 Ω and the assembled DSSCs delivered an optimum power conversion efficiency of 8.59%, superior to those of Pt-based cells (6.78 Ω and 7.46%, respectively). The unique bifunctional structure of the SnxPy conductive core coupled with the phosphorized metallic Snδ+ (0 < σ < 0.6) electrocatalytic shell accounts for its excellent electrocatalytic activity and electrical conductivity. In addition, the phosphorized tin-based composites were utilized as potential anodic material for lithium-ion batteries, in which the Sn–P@PCMs electrode showed a specific capacity of 743 mAh g–1 at 0.1C after 400 cycles and 435 mAh g–1 at 5C after 30 cycles. The superior Li-ion storage, cyclability, and rate performance of Sn–P@PCMs could be attributed to the incorporation of Sn–P nanoparticles into interconnected porous carbon microspheres that effectively buffered the large volumetric change and enhanced the electronic–ionic conductivity during the lithiation and delithiation process.

Theoretical investigations of selective cation doping as a novel design strategy for high-capacity lithium-rich cathode materials

On the route towards higher energy densities of lithium ion batteries (LIBs) for electromotive applications, the low capacity of state-of-the-art cathode materials is still a limiting factor. Lithium-rich layered oxides (LLOs), a composite of layered LiMO2 (M = Ni, Co, Mn) and Li2MnO3, are a promising material class, which exhibit high discharge capacities based on additional anionic redox activity but still suffer from oxygen release and correlated structural instability. In order to overcome these issues, which are mostly related to the Li2MnO3 parent structure, doping is a common strategy. In this study, the effects of different cation dopants on manganese and lithium sites of the Li2MnO3 structure were systematically studied using first-principles calculations based on density functional theory (DFT). By using cluster expansion methods the thermodynamically stable ground states of doped and delithiated structures were calculated. We show that the dopants have a severe influence on the delithiation process, a fact that is often neglected in theoretical studies of doped structures. Multivalent dopants on lithium sites, like Al3+ and Ti4+, have a strong effect on the electronic structure as well as on the initial redox potential of the material. Moreover, enhanced metal–oxygen bonding and a decreased oxidation of the oxygen anions during delithiation are observed which indicate a reduction of both, the irreversible release of oxygen as well as unwanted structural changes.

Fabrication of Silicon/Carbon Composite Material with Silicon Waste and Carbon Nanofiber Applied in Lithium-Ion Battery

Silicon (Si) is regarded as a promising material for lithium-ion battery anode because of high theoretical capacity. Nevertheless, Si faces particle pulverization and rapid capacity fading due to serious volume change during the lithiation and the delithiation process. In this work, a silicon/carbon composite constituted to Si powder and carbon nanofiber (CNF) is produced to solve the above issues as a new design structure of anode material. The Si powder was recycled from the silicon slicing waste in photovoltaic industry and the CNF was from dry rice straws. By mixing the purified Si powder with CNF, the composite was synthesized by the freeze-drying method and calcination. In the cyclic test, Si adding with 1 wt% CNF showed 3091 mAh/g capacity in the first cycle and 1079 mAh/g capacity after 100 cycles at the current density of 0.5 A/g, which were both better than pristine Si. SEM images also show the composite structure can eliminate cracks on the surface of the electrode during cycling. CNF attaching on Si particles can increase specific surface area, so binder can easily combine the active materials and the conductive materials together. This strategy enhances the structure stability and prevents the electrode from delamination.

Revealing the different effects of VIB transition metals X (X = Cr, Mo, W) on the electrochemical performance of Li-rich cathode Li2MnO3 by first-principles calculations.

Transition metal (TM) doping is widely applied to optimize the electrochemical performance of Li2MnO3, a promising cathode material of next-generation Li-ion batteries. The effect of doping on the performance of Li2MnO3 can vary with the elemental period of the doped TM. However, the rules of the different effects have not been well summarized, especially for TM elements within the same group. In this work, the effects of TM element (Cr, Mo, and W in group VIB) dilute doping on the electrochemical performance of Li2MnO3 are investigated through first-principles calculations. The results show that Mo and W can induce more obvious local lattice distortion. Although Cr, Mo and W doping can improve the electrochemical activity of Li2MnO3, they modify the charge compensation mechanism in different ways. At the initial stage of delithiation, both Cr and O undergo significant oxidation, and Mo can act as the main oxidation center, while W can trigger the electrochemical activity of Mn around it. The O ions around Mo and W are more stable during the delithiation due to the mild oxidation and the strong bonding of Mo-O and W-O. Furthermore, Cr, Mo and W dilute doping can promote the interlayer diffusion of Li at the initial charging state, which is gradually enhanced with the increase of the period of the doped elements, but Mo and W doping would hinder the intralayer diffusion of Li near the doping sites during further delithiation process. Our results highlight the difference in the effects of TM (in the same group) doping on the performance of Li2MnO3 and would facilitate fast and good design of Li-rich cathodes.