High-nickel Cathode Research Articles

Impact of High-Nickel Cathodes and Test Conditions on the Coulombic Efficiency of Lithium Metal in Advanced Electrolytes

Impact of High-Nickel Cathodes and Test Conditions on the Coulombic Efficiency of Lithium Metal in Advanced Electrolytes

Chemical Cross-linked Electrode-Electrolyte Interface Boosting the Structural Integrity of High Nickel Cathode Materials.

High nickel cathode material LiNixCoyMn1-x-yO2 (NCM) (x≥0.6) has represented the most critical material in virtue of outstanding specific capacity and low self-discharge. However, the high surface alkalinity and detrimental interfacial stability lead to the parasitic reaction and a series of phase deterioration. Herein, in situ cross-linking binder molecular chains with a 3D network structure to construct a stable and robust electrode-electrolyte interface, which can maintain the structural integrity and restrain side reactions is designed. Simultaneously, the cross-linked polymer can form stable hydrogen bonds with the pristine binder, greatly enhancing the bonding property. More importantly, the functional groups contained in the cross-linked co-polymers can chemically anchor transition metals, effectively preventing the dissolution of transition metals. Theoretical calculations confirm the feasibility and advancement of the anchoring mechanism, driving excellent structural stability and inhibition of the NiO impurity phase. This work provides a practical strategy to realize the high stability of cathode materials.

Bifunctional self-assembled molecular layer enables stable Ni-rich cathodes

Ni-rich layered oxides (LiNixCoyMnzO2, x ≥ 0.8, x + y + z = 1) are attractive cathode material candidates for building high-energy-density batteries owing to their higher specific capacity compared to their lower-Ni-content analogues. However, the high nickel content also brings challenges, such as storage instability in ambient conditions and poor cycle life. In this work, we propose a surface chemistry regulation strategy to simultaneously enhance the air storage stability and electrochemical stability of high-nickel cathode materials. A bifunctional ultrathin layer composed of trimethoxy(1H,1H,2H,2H-perfluorodecyl)silane (PFDTMS) was constructed on the surface of single-crystal LiNi0.83Co0.12Mn0.05O2 (NMC811) particles via molecular self-assembly. The passivating PFDTMS layer forms a superhydrophobic surface on the modified NMC811 particles, effectively mitigating deactivation reactions of NMC811 in air, and ensuring an uncompromised electrochemical performance of NMC811-based electrode after storing in air for two weeks. Furthermore, the self-assembled PFDTMS layer contributes to the formation of an electrochemical stable cathode–electrolyte interphase (CEI) on the NMC811 surface, improving the cycling stability of NMC811 at high cut-off voltages. The PFDTMS-based CEI also alleviates the chemical corrosion of NMC811 by the electrolyte, slows down the dissolution of transition metal ions during long term cycling. These findings present a straightforward, effective, eco-friendly, and cost-efficient approach to tackle the stability challenges inherent to Ni-rich layered cathode materials.

Rational design of hierarchically-solvating electrolytes enabling highly stable lithium metal batteries with high-nickel cathodes

The practical implementation of lithium-metal anodes in high-energy-density batteries with high-nickel cathodes requires the electrolytes that prevent dendrite growth, enable high rate performance, and provide adequate cathodic stability. Traditional electrolytes, however, struggle to fulfill these requirements, and a universal electrolyte design rule remains lacking. Herein, we introduce a hybrid strongly-weakly-solvating solvent (HSWSS) rule, based on Raman shifts and dielectric constants of solvents, to rationally design a multi-component hierarchically-solvating electrolyte (HSE) with a wide electrochemical window (>4.45 V), decent ionic conductivity (4.28 mS cm−1), and dendrite suppression ability. By introducing strongly-solvating cosolvent and appropriate Li salts into weakly solvating solvent, the HSE enable the Li||LiNi0.8Co0.1Mn0.1O2 cell (1.8 mAh cm−2, with 3 times excess ultrathin Li metal) to exhibit a high capacity retention of 74.3 % after 150 cycles at 1 C with a remarkable high Coulombic efficiency of 99.60 %. HSEs can also be conveniently prepared using commercially available solvents and salts, making them practical and cost effective for large-scale lithium-metal battery manufacturing. As a result, this rational design offers a new direction for the development of advanced electrolytes in high-energy-density lithium-metal batteries.

Multipoint adsorption constructs stable interface chemistry for high-nickel cathode material

LiNi0.83Co0.12Mn0.05O2 (NCM), a common commercial material, has been applied widely in electric mobility and large-scale energy storage fields with its high energy density and voltage platform. Nonetheless, the battery life of long-term operation is significantly harmed by the unstable crystal structure and cathode-electrolyte interface. Among these, capacity decay is closely associated with the dissolution of transition-metal ions. In the present work, a surface-modified strategy is proposed, that is, ethyl α-cyanoacrylate (ECA) is adsorbed to the transition metal site by polar functional group and then initiates its polymerization to obtain poly(ethyl α-cyanoacrylate) (PECA) coating. The functional coating can lessen the degradation of interface by-products and construct a thinner CEI film for lithium-ion fast conduction. Furthermore, the conformal and complete coating alleviates the structural degradation after the long-term cycle. The above benefits explain the improved performance of PECA modified material and perform well even at high-temperature and high-voltage tests, thus reflecting that the modification strategy provides practical guidance for improving the performance of lithium-ion power batteries.

Excellent cycling performance of high-nickel single-crystal cathode material by a well-tailored binary molten-salt method

Nickel-rich LiNixCoyMnzO2 (x + y + z = 1) cathode materials have been extensively studied due to their improved energy density and reduced cost in comparison to conventional layered oxides (LiCoO2) and perovskite-type compounds (LiFePO4). However, the further commercialization of polycrystalline nickel-rich layered cathodes are severely hampered by entrenched particle microcracking that evolves mainly from the randomly oriented grain boundaries in the primary particles. Herein, an environmental-friendly LiOH⋅H2O/Li2CO3 binary molten-salt method is introduced to synthesize single-crystal LiNi0.88Co0.09Mn0.03O2 with good crystallinity and dispersion, and the possible growth mechanism of the particles is inferred. The sample prepared at a lithium ratio of 1.7 (SC1.7) shows a lower degree of cation mixing and larger lithium layer spacing compared to control polycrystalline sample (PC), and the residual alkali is effectively removed from the surface of single crystal particles. These features enable SC1.7 to maintain robust structural stability during cycling, with the cycle retention at 1C rate and a voltage of 4.5 V to be 86.73% after 100 cycles. The desirable performance is rationally derived from the significant inhibition of microcracks in particles, and reduction of parasitic reactions. The unique binary molten-salt strategy provides a new avenue for the design of high-performance high-nickel cathode materials in lithium-ion batteries.

(Invited) Delineating the Intricacies Involved in the Synthesis of Cobalt-Free High-Nickel Layered Oxide Cathodes for Lithium-Ion Batteries

Improving the energy density and cost of lithium-ion batteries (LIBs) requires a rational compositional design of layered oxide LiNi1-x-yMnxCoyO2 (NMC) cathodes. The prevailing trend is to increase the nickel content in the cathode to maximize energy density, but high-nickel NMC generally suffers from surface and bulk instabilities that shorten battery life. Dopants, such as cobalt, can help mitigate these issues, but its supply shortage issue prohibits its usage especially in the massive electric vehicle market. Our recent finding suggests that a combination of manganese and aluminum in LiNi0.9Mn0.05Al0.05O2 (NMA-90) promotes attractive energy density, cycle life, rate capability and thermal stability, proving that cobalt can be eliminated in high-nickel cathodes. Post-mortem analysis further reveals that the Mn-Al combination provides synergistic improvements in structural and surface stabilities compared to LiNi0.9Mn0.05Co0.05O2 (NMC-90) and LiNi0.9Co0.05Al0.05O2 (NCA-90). A thorough understanding of the relationship between the synthesis condition and optimal materials properties of NMA-90 is necessary to enable its large-scale deployment. We will present findings from the calcination and coprecipitation study of several cobalt-free cathodes to elucidate this relationship. It is revealed that the cycle stability of LiNi0.9Mn0.1O2 (NM-90) is not dependent on Li/Ni mixing or primary particle size, but is dependent on the calcination temperature. Incorporating Al into NM-90 during coprecipitation reactions cause high internal porosity in the hydroxide precursor, which impacts the final morphology of the calcined cathodes and thus their electrochemical stability. The ongoing work in our lab provides insight on the synthesis sensitivity of NMA and strategizes methods to control its electrochemical properties.

(Digital Presentation) Renewable Itaconic Acid As a Cathode Additive Stabilizing Ni-Rich Layered Cathode Materials for Lithium-Ion Batteries

Renewable materials applied in lithium-ion batteries industry has obvious advantages because of its wide range of sources and low cost. The residual lithium compounds on the surface of nickel-rich LiNi1-x-yCoxMnyO2 (Ni-rich NCM) cathodes hinder its large-scale industrial application in lithium-ion batteries. In the past, researchers proposed several approaches including coating (Al2O3, Li3PO4), water washing coupling heat treatment. These conventional approaches have been found beneficial for mitigating the residual lithium and improving electrochemical performance of high rich nickel cathode. However, most of these used conventional additions are non-renewable precious metal or salt accompanied by extra processing/handling costs. More seriously, layer Ni-rich NCM cathodes cost more than lithium iron phosphate, because transition nickel salt is expensive. Obviously, it is crucial for Ni-rich NCM cathodes to develop green and low-cost modification process.In this work, renewable itaconic acid (IA) as a cathode addition is used to convert the residual lithium on the Ni-rich NCM cathodes into sacrificial organic lithium salts containing polar carboxylic acid and unsaturated carbon-carbon double bond to build the Li conductive cathode-electrolyte interphase (CEI) rich in organic component containing polycarbonates/polymeric specie during the electrochemical process. As a result, the capacity of the 0.5wt% IA modified NCM cathode retains 94.1 % after 90 cycles. Itaconic anhydride, an important renewable resource, is widely used in food processing and other fields because of its wide range of sources and low price. As such, our work proposes a practical approach to mitigates residual lithium issue and control CEI formation, developing high energy and long spans lithium-ion batteries by utilizing cheap and renewable organic acid. Figure 1

Impact of Morphology of Polycrystalline and Single Crystal Nickel Rich Cathode Particles on Performance

High nickel cathode material (NMC 811) is great candidate for high performance batteries. It has high specific capacity and lower utilization of cobalt. The morphology of the cathode particles is studied in a comprehensive manner, from the impact of synthesis parameters on primary particle size, to experimental characterization and replicating the key morphological features in computational model to elucidate the morphological features critical to the performance. The polycrystalline micron sized secondary particle is comprised of thousands of nanometers sized primary particles. The single crystal is generally 2 to 3 microns in size. The “single crystal” cathode particle may be cluster of few single crystals. The length scales of primary and secondary particles as well as internal porosity of polycrystalline cathode particles changes the characteristic diffusion length as well as surface area available for electrochemical reaction. Similarly, for single crystal, the size and the degree of clustering changes the diffusion characteristics and surface area. These variations are reflected in specific capacities obtained at different C-rates. Gaining an in-depth understanding of correlation of morphological features to performance would be helpful in directing the synthesis process. Figure 1

(John B. Goodenough Award of The Electrochemical Society) Oxide Revolution in Energy Storage

Lithium-ion batteries have become an integral part of our daily life. The triumph of lithium-ion batteries is due to their much higher energy density compared to the other rechargeable battery systems. The high energy density along with superior cycling stability became possible because of the use of oxide cathodes in lithium-ion cells. There are only three families of cathodes for practical lithium-ion cells, and all the three of them are oxides: layered, spinel, and polyanion oxide cathodes.As we move forward with vehicle electrification and renewable energy storage, multiple parameters, such as cost, energy density, power density, cycle life, safety, and environmental impact, need to be balanced. Among them, cost along with sustainability and supply chain issues is at the forefront. Cathode is the most expensive component in the cell. The oxide cathodes will still dominate the field, but with fierce efforts to reduce or eliminate less abundant and expensive metals in the cathode. This presentation will focus on eliminating the most expensive cobalt from layered oxide cathodes, then reducing the next expensive nickel in oxide cathodes, and finally replacing/eliminating lithium with sodium in oxide cathodes.Reducing or eliminating cobalt in layered oxide cathodes by increasing the nickel content helps to increase the energy density and reduce the cost, but cathodes with high nickel contents are plagued with cycle, thermal, and air instabilities along with severe scale-up challenges. This presentation will focus on overcoming these challenges with controlled compositional and synthesis designs along with a profound understanding of the intricacies involved with the aid of advanced characterization methodologies. Particularly, issues, such as what different dopants really do, which dopant does what, and which is critical between surface reactivity and crack, in stabilizing high-nickel cathodes will be discussed. The dependence of surface reorganization/degradation pathways on electrolytes and the importance of electrolyte composition and high-voltage stability in stabilizing the cathode-electrolyte interphase will be presented with both graphite and lithium-metal anodes.Finally, elimination of both cobalt and lithium while reducing the nickel content much further down will be described with sodium batteries based on layered oxide cathodes. Tailored electrolyte designs that provide long-life sodium cells with suppressed dendrites and enhanced safety will be presented.

Carbon-coated high nickel cathode nanosheet with stable structure for lithium-ion batteries

Carbon-coated high nickel cathode nanosheet with stable structure for lithium-ion batteries

Synergistic interphase modification with dual electrolyte additives to boost cycle stability of high nickel cathode for all-climate battery

B-containing electrolyte additives are widely used to enhance the cycle performance at low temperature and the rate capability of lithium-ion batteries by constructing an efficient cathode electrolyte interphase (CEI) to facilitate the rapid Li+ migration. Nevertheless, its wide-temperature application has been limited by the instability of B-derived CEI layer at high temperature. Herein, dual electrolyte additives, consisting of lithium tetraborate (Li2TB) and 2, 4-difluorobiphenyl (FBP), are proposed to boost the wide-temperature performances of LiNi0.6Co0.2Mn0.2O2 (NCM) cathode. Theoretical calculation and electrochemical performances analyses indicate that Li2TB and FBP undergo successive decomposition to form a unique dual-layer CEI. FBP acts as a synergistic filming additive to Li2TB, enhancing the high-temperature performance of NCM cathode while preserving the excellent low-temperature cycle stability and the superior rate capability conferred by Li2TB additive. Therefore, the capacity retention of NCM||Li cells using optimal FBP-Li2TB dual electrolyte additives increases to 100% after 200 cycles at −10 °C, 99% after 200 cycles at 25 °C, and 83% after 100 cycles at 55 °C, respectively, much superior to that of base electrolyte (63%/69%/45%). More surprisingly, galvanostatic charge/discharge experiments at different temperatures reveal that NCM||Li cells using FBP-Li2TB additives can operate at temperatures ranging from −40 °C to 60 °C. This synergistic interphase modification utilizing dual electrolyte additives to construct a unique dual-layer CEI adaptive to a wide temperature range, provides valuable insights to the practical applications of NCM cathodes for all-climate batteries.

Nanoscale electrical characterization of ambient-induced surface impurities on high-nickel cathode materials for lithium-ion batteries

One of the most critical points in the study of LIB-related materials is the extremely high reactivity of Li. In addition to pure Li metal, many Li-containing materials employed in LIBs are highly reactive under ambient conditions. Therefore, they should be stored and treated in an inert environment, such as vacuum chambers and gloveboxes filled with inert gases. In particular, most pristine cathode materials contain Li and are more reactive in air than pristine anode materials are. For instance, various impurities, mostly Li2CO3, are grown on the surface of pristine NCA (LiNixCoyAlzO2, x + y + z = 1) materials. The precise characterization of these ambient-induced surface impurities is critical for understanding the intrinsic properties of these cathode materials. In this study, we directly image and characterize ambient-induced surface impurities formed on the surface of high-Ni NCA (LiNi0.8Co0.15Al0.05O2) materials using Kelvin probe force microscopy (KPFM) and scanning spreading resistance microscopy (SSRM). The ambient-induced surface impurities show clearly distinguishable work functions and resistance features compared with the pristine NCA surface. In particular, it is confirmed that the resistance of ambient-induced impurities is significantly higher than that of pristine NCA materials, which can deteriorate the performance of LIB cells. This study provides direction for the fabrication, storage, and processing of LIB cathode materials.

Thermal Stability and Outgassing Behaviors of High-nickel Cathodes in Lithium-ion Batteries.

LiNiO2 -based high-nickel layered oxide cathodes are regarded as promising cathode materials for high-energy-density automotive lithium batteries. Most of the attention thus far has been paid towards addressing their surface and structural instability issues brought by the increase of Ni content (>90 %) with an aim to enhance the cycle stability. However, the poor safety performance remains an intractable problem for their commercialization in the market, yet it has not received appropriate attention. In this review, we focus on the gas generation and thermal degradation behaviors of high-Ni cathodes, which are critical factors in determining their overall safety performance. A comprehensive overview of the mechanisms of outgassing and thermal runaway reactions is presented and analyzed from a chemistry perspective. Finally, we discuss the challenges and the insights into developing robust, safe high-Ni cathodes.

All-fluorinated electrolyte for non-flammable batteries with ultra-high specific capacity at 4.7 V

Li metal batteries (LMBs) with LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes could release a specific energy of >500 Wh kg−1 by increasing the charge voltage. However, high-nickel cathodes working at high voltages accelerate degradations in bulk and at interfaces, thus significantly degrading the cycling lifespan and decreasing the specific capacity. Here, we rationally design an all-fluorinated electrolyte with addictive tri(2,2,2-trifluoroethyl) borate (TFEB), based on 3, 3, 3-fluoroethylmethylcarbonate (FEMC) and fluoroethylene carbonate (FEC), which enables stable cycling of high nickel cathode (LiNi0.8Co0.1Mn0.1O2, NMC811) under a cut-off voltage of 4.7 V in Li metal batteries. The electrolyte not only shows the fire-extinguishing properties, but also inhibits the transition metal dissolution, the gas production, side reactions on the cathode side. Therefore, the NMC811||Li cell demonstrates excellent performance by using limited Li and high-loading cathode, delivering a specific capacity >220 mA h g−1, an average Coulombic efficiency >99.6% and capacity retention >99.7% over 100 cycles.

Controlling the Microstructure of Cobalt-Free, High-Nickel Cathode Materials with Dopant Solubility for Lithium-Ion Batteries.

Microstructural engineering is becoming notably important in the realization of cobalt-free, high-nickel layered oxide cathodes for lithium-ion batteries since it is one of the most effective ways to improve the overall performance by enhancing the mechanical and electrochemical properties of cathodes. In this regard, various dopants have been investigated to improve the structural and interfacial stabilities of cathodes with doping. Yet, there is a lack of a systematic understanding of the effects of dopants on microstructural engineering and cell performances. Herein, we show controlling the primary particle size by adopting dopants with different oxidation states and solubilities in the host structure as an effective way for tuning the cathode microstructure and performance. The reduction in the primary particle size of cobalt-free high-nickel layered oxide cathode materials, e.g., LiNi0.95Mn0.05O2 (NM955), with high-valent dopants, such as Mo6+ and W6+, gives a more homogeneous distribution of Li during cycling with suppressed microcracking, cell resistance, and transition-metal dissolution compared to lower-valent dopants, such as Sn4+ and Zr4+. Accordingly, this approach offers promising electrochemical performance with cobalt-free high-nickel layered oxide cathodes.

Developing multifunctional amide additive by rational molecular design for high-performance Li metal batteries

Rechargeable lithium batteries based on lithium metal anodes and high-nickel cathodes have unparalleled advantages in energy density. However, the massive growth of lithium dendrites and the rapid degradation of high-nickel ternary oxides in commercial electrolyte have greatly hindered their application. To circumvent this issue, we design a series of analogs as electrolyte additives by adopting acetyls as connecting units to splice multiple functional groups. Among these additives, N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA) stands out due to the rational molecular configuration and the synergistic complementarity of amide, trifluoromethyl and trimethylsilyl groups. The cycling reversibility of the lithium metal anode (1050 h at 1 mA cm−1 to 1 mAh cm−1) and the capacity retention of the LiNi0.9Co0.05Mn0.05O2 cathode (85.9 % at 3–4.3 V after 300 cycles) in MSTFA modified carbonate electrolyte are tremendously enhanced. In addition, the safety of the battery and the tolerance to harsh working conditions (high & low temperature, high-voltage) are also ameliorated. This work sheds light on the relationship between structure and activity of molecules as well as provides a novel idea for modular design of additives.

A Self-Reconfigured, Dual-Layered Artificial Interphase Towards High-Current-Density Quasi-Solid-State Lithium Metal Batteries.

The uncontrollable dendrite growth and unstable solid electrolyte interphase have long plagued the practical application of Li metal batteries. Herein, we demonstrate a dual-layered artificial interphase LiF/LiBO-Ag that is simultaneously reconfigured via an electrochemical process to stabilize the lithium anode. This dual-layered interphase consists of a heterogeneous LiF/LiBO glassy top layer with ultrafast Li-ion conductivity and lithiophilic Li-Ag alloy bottom layer, which synergistically regulates the dendrite-free Li deposition, even at high current densities. As a result, Li||Li symmetric cells with LiF/LiBO-Ag interphase achieve an ultralong lifespan (4500h) at an ultrahigh current density and area capacity (20mA cm-2 , 20 mAh cm-2 ). LiF/LiBO-Ag@Li anodes were successfully applied in quasi-solid-state batteries, showing excellent cycling performances in symmetric cells (8mA cm-2 , 8 mAh cm-2 , 5000h) and full cells. Furthermore, a practical quasi-solid-state pouch cell coupling with a high-nickel cathode exhibits a stable cycling with a capacity retention of over 91% after 60 cycles at 0.5 C, which is comparable or even better than that in liquid-state pouch cells. Additionally, a high-energy-density quasi-solid-state pouch cell (10.75 Ah, 448.7Wh kg-1 ) were successfully accomplished. This well-orchestrated interphase design provides new guidance in engineering highly stable interphase towards practical high-energy-density lithium metal batteries. This article is protected by copyright. All rights reserved.

Synthesis and characterization of Co-free NMA cathodes for fast charging lithium-ion batteries

The new high nickel cathode LiNi1−x−yMnxAlyO2 (NMA) has attracted the attention of researchers, but the high rate performance has shortcoming compared to the conventional cobalt-cathode. In this paper, NaAlO2 was used as the aluminum source to effectively inhibit the preferential precipitation of Al(OH)3 and the chemical composition was uniformly distributed in particles. LiNi0.80Mn0.1Al0.1O2 (NMA80), LiNi0.90Mn0.05Al0.05O2 (NMA90) and LiNi0.95Mn0.025Al0.025O2 (NMA95) cobalt-free materials were synthesized by this optimized chemical co-precipitation method and calcinations and all three materials show high crystallinity and purity. The electrochemical performance and phase characterization analysis of Ni-Mn-Al materials were carried out and the effects of Al and Mn elements on the materials were investigated. The specific capacity of NMA95 is 210.6 mAh/g at 0.1 C under a voltage range of 2.75–4.30 V and NMA90 can also reach 201.1 mAh/g. In addition, NMA95 and NMA90 also have excellent specific capacity at 1 C, the discharge capacity are 195.3 and 183.2 mAh/g respectively. However, the cyclic stability of NMA95 at 1 C is slightly inadequate with 81.10% retention rate and NMA90 is the best with 95.52% retention rate. As for NMA80, the overall capacity is low. In particular, the rate performance of NMA90 is much higher than the other two materials. The discharge capacity of NMA90 can still reach 172.3 mAh/g at 5 C high discharge rate. Excellent specific capacity at high rate is promising for the development of fast charging technology. NaAlO2 effectively control the precipitation rate of Al, and the rate performance of the synthetic material is optimized. It is expected that performance of NMA for next-generation lithium-ion batteries could be improved by this process.

In Situ Polymerization Anchoring Effect Enhancing the Structural Stability and Electrochemical Performance of the LiNi0.8Co0.1Mn0.1O2 Cathode Material

LiNixCoyMn1-x-yO2 (NCM) is identified as the most classical cathode material on account of its outstanding specific capacity, moderate price, and high safety. However, the surface stability of the high nickel cathode material is poor, which is extremely sensitive to air. Herein, we discover that the electron donor functional groups of organic polymers can form a stable coordination anchoring effect with nickel atoms in the cathode material that can provide an empty orbit through electron transfer, which not only enhances the mutual interface stability between the polymer coating and NCM but also greatly inhibits the decomposition of metal ions in the deintercalation/intercalation process. Density functional theory calculations and first principles reveal that there are coordination bonds and charge transfers between poly(3,4-ethylenedioxythiophene) (PEDOT) and NCM. Consequently, the modified material displayed excellent cyclic stability, with a capacity retention of 91.93% at 1 C after 100 cycles and a rate property of 143.8 mA h g-1 at 5 C. Moreover, structural analysis indicated that the enhanced cycling stability resulted from the suppression of irreversible phase transitions of PEDOT-coated NCM. This unique mechanism provides a thought for organic coating and surface modification of NCM materials.