Exceptional Rate Performances of Li-Rich Mn-Based Cathodes Enabled by Boron-Based Additives-Driven Self-Optimized Interface.

Li-rich Mn-based cathode material (LRM), as a promising cathode for high energy density lithium batteries, suffers from severe side reactions in conventional lithium hexafluorophosphate (LiPF6)-based carbonate electrolytes, leading to unstable interfaces and poor rate performances. Herein, a boron-based additives-driven self-optimized interface strategy is presented to dissolve low ionic conductivity LiF nanoparticles at the outer cathode electrolyte interface, leading to the optimized interfacial components, as well as the enhanced Li ion migration rate in electrolytes. Being attributed to these superiorities, the LRM||Li battery delivers a high-capacity retention of 92.19% at 1C after 200 cycles and a low voltage decay of 1.08 mV/cycle. This work provides a new perspective on the rational selection of functional additives with an interfacial self-optimized characteristic to achieve a long lifespan LRM with exceptional rate performances.

Zero-Strain Sodium Nickel Ferrocyanide as Cathode Material for Sodium-Ion Batteries with Ultra-Long Lifespan.

Prussian blue analogues are recognized as one of the most promising cathode materials for sodium-ion batteries (SIBs) owing to the open 3D framework structure with large interstitial sites and developed Na-ion diffusion channels. However, high content of anion vacancy and poor structural stability have hampered the prospect of their application. In this work, sodium nickel ferrocyanide (Na1.34Ni[Fe(CN)6]0.92, NNHCF) is proposed as cathode material for SIBs. N-coordinated Ni-ion can boost NNHCF to possess less Fe[(CN)6]4- defect, low Na-ion migration barrier, and more negative formation energy compared with Na0.91Cu[Fe(CN)6]0.77 (NCHCF), thus exhibiting more active sites, fast electrochemical kinetics behavior and great structure stability. It is confirmed that NNHCF undergoes a solid solution mechanism without phase evolution for reversible Na-ion intercalation/deintercalation, employing Fe associated with C atom as redox center for charge compensation. Therefore, NNHCF contributes a high initial energy density of 180.94 Wh·g-1 at 10 mA·g-1, excellent rate capability, superior cycling stability with ultra-long lifespan of 13 000 cycles, and low fading rate of 0.0027% per cycle at 500 mA·g-1. This work sheds light on the construction of low-defect PBA cathodes with outstanding dynamics and stability.

Surface Pinning of Mn by Oxidation State Control for the Synthesis of Cobalt-Free, Ni-Rich, Core/Shell Structured Cathode Materials.

Motivated by the increasing cost, environmental concerns, and limited availability of Co, researchers are actively seeking alternative cathode materials for lithium-ion batteries. A promising strategy involves structure-modified materials, such as a NiMn core/shell system. This design leverages the high energy density of a Ni-rich core while employing an Mn-rich shell to enhance interfacial stability by suppressing unwanted reactions with the electrolyte. This approach offers improved cycling stability and reduced reliance on Co. However, the interdiffusion of Mn ions between the core and shell remains a significant challenge during synthesis. This work presents a facile approach to address the issue of Mn interdiffusion in core/shell cathode materials. The study demonstrates that partial oxidation of the precursor during the drying stage effectively enhances the Mn oxidation state. This strategy successfully suppresses Mn interdiffusion during subsequent calcination, leading to the preservation of the core/shell architecture in the final cathode material. This optimized structure mitigates interfacial reactions, enhances chemomechanical properties, and reduces crosstalk, a major contributor to rollover failure. This work presents a novel approach for synthesizing high-performance core/shell cathode materials for next-generation lithium-ion batteries.

Doping-Induced Surface and Grain Boundary Effects in Ni-Rich Layered Cathode Materials.

In this work, the effects of dopant size and oxidation state on the structure and electrochemical performance of LiNi0.8Co0.1Mn0.1O2 (NCM811) are investigated. It is shown that doping with boron (B) which has a small ionic radius and an oxidation state of 3+, leads to the formation of a boron oxide-containing surface coating (probably Li3BO3), mainly on the outer surface of the secondary particles. Due to this effect, boron only slightly affects the size of the primary particle and the initial capacity, but significantly improves the capacity retention. On the other hand, the dopant ruthenium (Ru) with a larger ionic radius and a higher oxidation state of 5+ can be stabilized within the secondary particles and does not experience a segregation to the outer agglomerate surface. However, the Ru dopant preferentially occupies incoherent grain boundary sites, resulting in smaller primary particle size and initial capacity than for the B-doped and pristine NCM811. This work demonstrates that a small percentage of dopant (2 mol%) cannot significantly affect bulk properties, but it can strongly influence the surface and/or grain boundary properties of microstructure and thus the overall performance of cathode materials.

Urchin-Like Mesoporous TiN Hollow Sphere Enabling Promoted Electrochemical Kinetics of Bromine-Based Flow Batteries.

Bromine-based flow batteries (BFB) have always suffered from poor kinetics due to the sluggish Br3 -/Br- redox, hindering their practical applications. Developing cathode materials with high catalytic activity is critical to address this challenge. Herein, the in-depth investigation for the free energy of the bromine redox electrode is conducted initially through DFT calculations, establishing the posterior desorption during oxidation as the rate-determining step. An urchin-like titanium nitride hollow sphere (TNHS) composite is designed and synthesized as the catalyst for bromine redox. The large difference in Br- and Br3 - adsorption capability of TNHS promotes rapid desorption of generated Br3 - during the oxidation process, liberating active sites timely to enable smooth ongoing reactions. Besides, the urchin-like microporous/mesoporous structure of TNHS provides abundant active surface for bromine redox reactions, and ample cavities for the bromine accommodation. The inherently high conductivity of TNHS enables facile electron transfer through multiple channels. Consequently, zinc-bromide flow batteries with TNHS catalyst exhibit significantly enhanced kinetics, stably operating at 80 mA cm-2 with 82.78% energy efficiency. Overall, this study offers a solving strategy and catalyst design approach to the sluggish kinetics that has plagued bromine-based flow batteries.

Electrochemical Failure Mechanism of δ-MnO2 in Zinc Ion Batteries Induced by Irreversible Layered to Spinel Phase Transition.

Phase transitions of Mn-based cathode materials associated with the charge and discharge process play a crucial role on the rate capability and cycle life of zinc ion batteries. Herein, a microscopic electrochemical failure mechanism of Zn-MnO2 batteries during the phase transitions from δ-MnO2 to λ-ZnMn2O4 is presented via systematic first-principle investigation. The initial insertion of Zn2+ intensifies the rearrangement of Mn. This is completed by the electrostatic repulsion and co-migration between guest and host ions, leading to the formation of λ-ZnMn2O4. The Mn relocation barrier for the λ-ZnMn2O4 formation path with 1.09 eV is significantly lower than the δ-MnO2 re-formation path with 2.14 eV, indicating the irreversibility of the layered-to-spinel transition. Together with the phase transition, the rearrangement of Mn elevates the Zn2+ migration barrier from 0.31 to 2.28 eV, resulting in poor rate performance. With the increase of charge-discharge cycles, irreversible and inactive λ-ZnMn2O4 products accumulate on the electrode, causing continuous capacity decay of the Zn-MnO2 battery.

High-Capacity and Ultra-Long-Life Mg-Metal Batteries Enabled by Intercalation-Conversion Hybrid Cathode Materials.

The advancement of rechargeable Mg-metal batteries (RMBs) is severely impeded by the lack of suitable cathode materials. Despite the good cyclic stability of intercalation-type compounds, their specific capacity is relatively low. Conversely, the conversion-type cathodes can deliver a higher capacity but often suffer from poor cycling reversibility and stability. Herein, a WSe2/Se intercalation-conversion hybrid material with elemental Se uniformly distributed into WSe2 nanosheets is fabricated via a simple solvothermal method for high-performance RMBs. The uniformly introduced Se confined in WSe2 nanosheets can not only efficiently improve the conductivity of the hybrid cathodes, facilitating the fast electron transport and ion diffusion, but also provide additional specific capacity. Besides, the WSe2 can effectively inhibit the detrimental Se dissolution and polyselenide shuttle, thereby activating the activity of Se and improving its utilization. Consequently, the synergy of intercalation and conversion mechanisms endows WSe2/Se hybrids with superior reversible capacity of 252 mAh g-1 at 0.1 A g-1 and ultra-long cyclability of up to 5000 cycles at 2.0 A g-1 with capacity retention of 78.1%. This work demonstrates the feasibility of the strategy by integrating intercalation and conversion mechanisms for developing high-performance cathode materials for RMBs.

p/n-Type Polyimide Covalent Organic Frameworks for High-Performance Cathodes in Sodium-Ion Batteries.

Covalent organic frameworks (COFs) are viewed as promising organic electrode materials for metal-ion batteries due to their structural diversity and tailoring capabilities. In this work, firstly using the monomers N,N,N',N'-tetrakis(4-aminophenyl)-1,4-phenylenediamine (TPDA) and terephthaldehyde (TA), p-type phenylenediamine-based imine-linked TPDA-TA-COF is synthesized. To construct a bipolar redox-active, porous and highly crystalline polyimide-linked COF, i.e., TPDA-NDI-COF, n-type 1,4,5,8-naphthalene tetracarboxylic dianhydride (NDA) molecules are incorporated into p-type TPDA-TA-COF structure via postsynthetic linker exchange method. This tailored COF demonstrated a wide potential window (1.03.6 V vs Na+/Na) with dual redox-active centers, positioning it as a favorable cathode material for sodium-ion batteries (SIBs). Owing to the inheritance of multiple redox functionalities, TPDA-NDI-COF can deliver a specific capacity of 67 mAh g-1 at 0.05 A g-1, which is double the capacity of TPDA-TA-COF (28 mAh g-1). The incorporation of carbon nanotube (CNT) into the TPDA-NDI-COF matrix resulted in an enhancement of specific capacity to 120 mAh g-1 at 0.02 A g-1. TPDA-NDI-50%CNT demonstrated robust cyclic stability and retained a capacity of 92 mAh g-1 even after 10 000 cycles at 1.0 A g-1. Furthermore, the COF cathode exhibited an average discharge voltage of 2.1 V, surpassing the performance of most reported COF as a host material.

Achieving a Rapid Na+ Migration and Highly Reversible Phase Transition of NASICON for Sodium-Ion Batteries with Suppressed Voltage Hysteresis and Ultralong Lifespan.

Sodium ion batteries have attracted great attention for large scale energy storage devices to replace lithium-ion batteries. As a promising polyanionic cathode material of sodium-ion batteries, Na3V2(PO4)2F3 (NVPF) belonging to NASICON exhibits large gap space and excellent structural stability, leading to a high energy density and ultralong cycle lifespan. To improve its stability and Na ion mobility, K+ cations are introduced into NVPF crystal as in situ partial substitution for Na+. The influence of K+ in situ substitution on crystal structure, electronic properties, kinetic properties, and electrochemical performance of NVPF are investigated. Through ex situ examination, it turns out that K+ occupied Na1 ion, in which the K+ does not participate in the charge-discharge process and plays a pillar role in improving the mobility of Na+. Moreover, the doping of K+ cation can reduce the bandgap energy and improve the electronic conductivity. Besides, the optimal K+ doping concentration in N0.92K0.08VPF/C is found so as to achieve rapid Na+ migration and reversible phase transition. The specific capacity of N0.92K0.08VPF/C is as high as 128.8 mAh g-1 at 0.2 C, and at 10 C its rate performance is excellent, which shows a capacity of 113.3 mAh g-1.

Li3V2(PO4)3 Cathode Material: Synthesis Method, High Lithium Diffusion Coefficient and Magnetic Inhomogeneity.

Li3V2(PO4)3 cathodes for Li-ion batteries (LIBs) were synthesized using a hydrothermal method with the subsequent annealing in an argon atmosphere to achieve optimal properties. The X-ray diffraction analysis confirmed the material's single-phase nature, while the scanning electron microscopy revealed a granular structure, indicating a uniform particle size distribution, beneficial for electrochemical performance. Magnetometry and electron spin resonance studies were conducted to investigate the magnetic properties, confirming the presence of the relatively low concentration and highly uniform distribution of tetravalent vanadium ions (V4+), which indicated low lithium deficiency values in the original structure and a high degree of magnetic homogeneity in the sample, an essential factor for consistent electrochemical behavior. For this pure phase Li3V2(PO4)3 sample, devoid of any impurities such as carbon or salts, extensive electrochemical property testing was performed. These tests resulted in the experimental discovery of a remarkably high lithium diffusion coefficient D = 1.07 × 10-10 cm2/s, indicating excellent ionic conductivity, and demonstrated impressive stability of the material with sustained performance over 1000 charge-discharge cycles. Additionally, relithiated Li3V2(PO4)3 (after multiple electrochemical cycling) samples were investigated using scanning electron microscopy, magnetometry and electron spin resonance methods to determine the extent of degradation. The combination of high lithium diffusion coefficients, a low degradation rate and remarkable cycling stability positions this Li3V2(PO4)3 material as a promising candidate for advanced energy storage applications.

Molecular Crystal Structure Simulations and Structure-Magnetic Properties of LiFePO4 Composite Particles Optimized by La.

In this study LiFePO4/C composite particles were synthesized using five different carbon sources via a one-step sol-gel method. La-doped LiFePO4 was also synthesized using the sol-gel method. The XRD pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h indicates that as the doping ratio increased, the sample's cell volume first increased then decreased, reaching a maximum value of 293.36 Å3 (x = 0.94, y = 0.06). The XRD patterns of Li0.92La0.08FePO4 after being calcined at different temperatures for 10 h indicate that with increasing calcination temperature, the (311) diffraction peak drifted toward a smaller diffraction angle. Similarly, the XRD patterns of Li0.92La0.08FePO4 after being calcined at 700 °C for different durations indicate that with increasing calcination times, the (311) diffraction peak drifted toward a larger diffraction angle. The infrared spectrum pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h shows absorption peaks corresponding to the vibrations of the Li-O bond and PO43- group. An SEM analysis of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicates that the particles were irregular in shape and of uniform size. The hysteresis loops of Li0.92La0.08FePO4 after being calcined at 600 °C, 700 °C, or 800 °C for 10 h indicate that with increasing calcination temperature, the Ms gradually increased, while the Mr and Hc decreased, with minimum values of 0.08 emu/g and 58.21 Oe, respectively. The Mössbauer spectra of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicate that all samples contained Doublet(1) and Doublet(2) peaks, dominated by Fe2+ compounds. The proportions of Fe2+ were 85.5% (x = 1, y = 0), 89.9% (x = 0.96, y = 0.04), and 96.0% (x = 0.92, y = 0.08). The maximum IS and QS of Doublet(1) for the three samples were 1.224 mm/s and 2.956 mm/s, respectively.

Resource Recovery of Spent Lithium-Ion Battery Cathode Materials by a Supercritical Carbon Dioxide System.

The increasing global market size of high-energy storage devices due to the boom in electric vehicles and portable electronics has caused the battery industry to produce a lot of waste lithium-ion batteries. The liberation and de-agglomeration of cathode material are the necessary procedures to improve the recycling derived from spent lithium-ion batteries, as well as enabling the direct recycling pathway. In this study, the supercritical (SC) CO2 was innovatively adapted to enable the recycling of spent lithium-ion batteries (LIBs) based on facilitating the interaction with a binder and dimethyl sulfoxide (DMSO) co-solvent. The results show that the optimum experimental conditions to liberate the cathode particles are processing at a temperature of 70 °C and 80 bar pressure for a duration of 20 min. During the treatment, polyvinylidene fluoride (PVDF) was dissolved in the SC fluid system and collected in the dimethyl sulfoxide (DMSO), as detected by the Fourier Transform Infrared Spectrometer (FTIR). The liberation yield of the cathode from the current collector reaches 96.7% under optimal conditions and thus, the cathode particles are dispersed into smaller fragments. Afterwards, PVDF can be precipitated and reused. In addition, there is no hydrogen fluoride (HF) gas emission due to binder decomposition in the suggested process. The proposed SC-CO2 and co-solvent system effectively separate the PVDF from Li-ion battery electrodes. Thus, this approach is promising as an alternative pre-treatment method due to its efficiency, relatively low energy consumption, and environmental benign features.

Recycling and Reuse of Spent LIBs: Technological Advances and Future Directions.

Recovering valuable metals from spent lithium-ion batteries (LIBs), a kind of solid waste with high pollution and high-value potential, is very important. In recent years, the extraction of valuable metals from the cathodes of spent LIBs and cathode regeneration technology are still rapidly developing (such as flash Joule heating technology to regenerate cathodes). This review summarized the studies published in the recent ten years to catch the rapid pace of development in this field. The development, structure, and working principle of LIBs were firstly introduced. Subsequently, the recent developments in mechanisms and processes of pyrometallurgy and hydrometallurgy for extracting valuable metals and cathode regeneration were summarized. The commonly used processes, products, and efficiencies for the recycling of nickel-cobalt-manganese cathodes (NCM/LCO/LMO/NCA) and lithium iron phosphate (LFP) cathodes were analyzed and compared. Compared with pyrometallurgy and hydrometallurgy, the regeneration method was a method with a higher resource utilization rate, which has more industrial application prospects. Finally, this paper pointed out the shortcomings of the current research and put forward some suggestions for the recovery and reuse of spent lithium-ion battery cathodes in the future.

Fluorinated bamboo-structure carbon nanotubes: as attractive substrates for the cathodes of lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries have gained considerable attention for high theoretical specific capacity and energy density. However, their development is hampered by the poor electrical conductivity of sulfur and the shuttle of polysulfides. Herein, the acidified bamboo-structure carbon nanotubes (BCNTs) were mixed with polyvinylidene difluoride and pyrolyzed at high-temperature to obtain the fluorinated bamboo-structure carbon nanotubes (FBCNTs), which were compounded with sulfur as the cathode. The prepared S@FBCNTs with sulfur loading reaching 74.2 wt.% shows a high initial specific capacity of 1407.5 mAh·g-1at the discharge rate of 0.1 C. When the discharge rate was increased to 5 C, the capacity could be maintained at 622.3 mAh·g-1. The electrical conductivity of carbon nanotubes is effectively improved by semi-ionic C-F bonds formed by the doped F atoms and carbon atoms. Simultaneously, the surface of the F-containing carbon tubes exhibits strong polarity and strong chemisorption effect on polysulfides, which inhibits the shuttle effect of Li-S batteries.

A 3D COF constructed by interlayer crosslinking of 2D COF as cathode material for lithium-sulfur batteries.

The design and construction of three-dimensional covalent organic frameworks (3D COF) remains a major challenge, and it is necessary to explore new strategies to synthesize 3D COF with ideal structure. Here, we utilize two-dimensional covalent organic framework (2D COF) with allyl side chain to achieve interlayer crosslinking through olefin metathesis reaction, thereby constructing a 3D COF with cage-like structures. This new material named CAGE-COF has larger specific surface area and more open pore structure than the original 2D COF. The cathode material with CAGE-COF retained 78.7% of its initial capacity after 500 cycles, and the fading rate is 0.04% each cycle.

Structure and Magnetic Properties of AO and LiFePO4/C Composites by Sol-Gel Combustion Method.

LiFePO4 takes advantage of structure stability, safety and environmental friendliness, and has been favored by the majority of scientific researchers. In order to further improve the properties of LiFePO4, AO-type metal oxides (MgO and ZnO) and LiFePO4/C composites were successfully prepared by a two-step sol-gel method. The effects of AO-type metal oxides (MgO and ZnO) on LiFePO4/C composites were studied. TG, XRD, FTIR, SEM and VSM analysis showed that the final product of the MgO and LiFePO4/C composite was about 70.5% of the total mass of the precursor; the complete main diffraction peak of LiFePO4 and MgO can be found without obvious impurity at the diffraction peak; there is good micro granularity and dispersion; the particle size is mainly 300 nm; the saturation magnetization (Ms), the residual magnetization (Mr) and the area of hysteresis loop are increased with the increase in MgO content; and the maximum Ms is 11.11 emu/g. The final product of ZnO and LiFePO4/C composites is about 69% of the total mass of precursors; the complete main diffraction peak of LiFePO4 and ZnO can be found without obvious impurity at the diffraction peak; there is good micro granularity and dispersion; the particle size is mainly 400 nm; and the coercivity (Hc) first slightly increases and then gradually decreases with the increase of zinc oxide.

A High-Energy NASICON-Type Na3.2 MnTi0.8 V0.2 (PO4 )3 Cathode Material with Reversible 3.2-Electron Redox Reaction for Sodium-Ion Batteries.

Na superionic conductor (NASICON) structured cathode materials with robust structural stability and large Na+ diffusion channels have aroused great interest in sodium-ion batteries (SIBs). However, most of NASICON-type cathode materials exhibit redox reaction of no more than three electrons per formula, which strictly limits capacity and energy density. Herein, a series of NASICON-type Na3+x MnTi1-x Vx (PO4 )3 cathode materials are designed, which demonstrate not only a multi-electron reaction but also high voltage platform. With five redox couples from V5+/4+ (≈4.1 V), Mn4+/3+ (≈4.0 V), Mn3+/2+ (≈3.6 V), V4+/3+ (≈3.4 V), and Ti4+/3+ (≈2.1 V), the optimized material, Na3.2 MnTi0.8 V0.2 (PO4 )3 , realizes a reversible 3.2-electron redox reaction, enabling a high discharge capacity (172.5 mAh g-1 ) and an ultrahigh energy density (527.2 Wh kg-1 ). This work sheds light on the rational construction of NASICON-type cathode materials with multi-electron redox reaction for high-energy SIBs.

Unveiling the Role and Mechanism of Nb Doping and In Situ Carbon Coating on Improving Lithium-Ion Storage Characteristics of Rod-Like Morphology FeF3 ·0.33H2 O.

Given the inherent characteristics of transition metal fluorides and open tunnel-type frameworks, intercalation-conversion-type FeF3 ·0.33H2 O has attracted widespread attention as a promising lithium-ion battery cathode material with high operating voltage and high energy density. However, its low electronic conductivity and poor structural stability impede its practical application in high-rate capacity and long-lifetime batteries. Herein, rod-like Nb-substituted FeF3 ·0.33H2 O (Nb-FeF3 ·0.33H2 O@C) nanocrystals with a carbon coating derived from in situ carbonization in an ionic liquid are deliberately designed and prepared. Based on first-principles calculations and electrochemical analysis, it is shown that substitution of Nb into a proportion of Fe sites can dramatically reduce the total energy of the system and the bandgap, thus boosting the structural stability and electronic conductivity of FeF3 ·0.33H2 O. Simultaneously, the combination of a surface conductive carbon coating and assembly of the nanoparticles into a rod-like mesoporous architecture can produce an omni-directional ion/electron transmission network and a robust 3D composite structure. The Nb-FeF3 ·0.33H2 O@C composite with 3% Nb-doping displays high capacity (583.2 mAh g-1 at 0.2 C), good rate capacity (187.8 mAh g-1 at a high rate of 5.0 C), and excellent long-term cycle stability (160.4 mAh g-1 after 300 long cycles).

Recent Advances on Spinel Zinc Manganate Cathode Materials for Zinc-Ion Batteries.

Zinc metal is abundant in nature, non-toxic, harmless, and cheap. Zinc-ion batteries (ZIBs) have also emerged as the times require, which has attracted scholars' research interest. In the zinc-ion batteries, the cathode material is indispensable. Manganese oxides are widely used in electrode materials because of their various valence states (+2, +3, +4, +7). ZnMn2 O4 (ZMO) is a mixed metal oxide with a spinel structure similar to LiMn2 O4 . Due to the synergistic effect of Zn and Mn, it has the advantages of high theoretical capacity. In recent years, researchers have gradually applied ZnMn2 O4 to zinc ion batteries. In order to obtain high-energy-density zinc ion batteries, it is also very important to match electrolytes with a wide operating voltage window and develop a highly reversible anode. In the first instance, we investigate the research progress of spinel ZnMn2 O4 as a reliable candidate material for zinc ion batteries. Later on, we review the optimization and modification measures of anode and electrolyte to improve the electrochemical properties of spinel ZnMn2 O4 . On this basis, we propose the reasonable research direction and development prospects for this material. It is hoped that there will be a help to researchers in this field.

Developments in Surface/Interface Engineering of Ni-Rich Layered Cathode Materials.

Ni-rich layered cathodes with high energy densities reveal an enormous potential for lithium-ion batteries (LIBs), however, their poor stability and reliability have inhibited their application. To ensure their stability over extensive cycles at high voltage, surface/interface modifications are necessary to minimize the adverse reactions at the cathode-electrolyte interface (CEI), which is a critical factor impeding electrode performance. Therefore, this review provides a comprehensive discussion on the surface engineering of Ni-rich cathode materials for enhancing their lithium storage property. Based on the structural characteristics of the Ni-rich cathode, the major failure mechanisms of these structures during synthesis and operation are summarized. Then the existing surface modification techniques are discussed and compared. Recent breakthroughs in various surface coatings and modification strategies are categorized and their unique functionalities in structural protection and performance-enhancing are elaborated. Finally, the challenges and outlook on the Ni-rich cathode materials are also proposed.