Room temperature, liquid-phase Al<sub>2</sub>O<sub>3</sub> surface coating approach for Ni-rich layered oxide cathode material

Neudeck, Sven; Strauss, Florian; García, Gonzalo Rodríguez; Wolf, Hannes; Janek, Jürgen; Hartmann, Pascal; Brezesinski, Torsten

doi:10.1039/c8cc09618j

Cited by 90 publications

(74 citation statements)

References 20 publications

(28 reference statements)

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“…[60][61][62] Typically, the ionic conductivity becomes higher for nanocrystalline materials, but these are generally poor ionic conductors. On the other hand, binary compounds like Al 2 O 3 and ZrO 2 , [63][64][65] while demonstrating utility as CAM coatings in conventional lithium-ion batteries, have not found broad acceptance for SSB architectures. Nevertheless, it may be that Li-free binary coatings of this kind become lithiated during formation or in situ during electrochemical cycling, thereby generating a ternary oxide coating and conferring the required ionic properties.…”

Section: Figurementioning

confidence: 99%

On the Functionality of Coatings for Cathode Active Materials in Thiophosphate‐Based All‐Solid‐State Batteries

Culver

Koerver

Zeier

et al. 2019

Advanced Energy Materials

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achievable by SSBs. Meanwhile, polymer-, oxide-, and sulfide-based ionic conductors are being heavily investigated as the solid electrolyte (SE) separator. [9][10][11][12][13][14][15] Nevertheless, recent estimates [16,17] show that only batteries possessing sulfide-based SEs will be leading contenders for room-temperature applications.The sulfides, which are better denoted as thiophosphates, provide the highest lithium-ion conductivity, a relatively low E modulus, and can be processed at low temperatures. [2,3,18] Currently, only thiophosphates allow for the preparation of thick cathode composites with sufficient rate capability. [19,20] Unfortunately, thiophosphates also have a rather narrow electrochemical stability window, i.e., the onset of oxidative decomposition begins even before 3 V versus Li + /Li due to S(0)/S(−2) redox reactions, while reductive decomposition is theoretically expected at potentials of about 1.7 V versus Li + /Li due to P(+5)/P(−3) redox reactions. [21,22] Importantly, the perfect SE does not actually exist. The perfect SE would combine the ionic transport properties of thiophosphates, the mechanical properties of polymers, and the oxidation stability of oxides. Therefore, in order to exploit the superionic transport properties of thiophosphates, the implementation of protective coatings to overcome the intrinsic electrochemical instabilities is most certainly a necessity. The thermodynamic prerequisites for coatings (Figure 1) have already been treated in a number of theoretical papers, [18,21,[23][24][25] which provide the initial design guidelines.Beyond the thermodynamic considerations, it is well known that within SSBs, thiophosphate SEs are oxidized and decomposed in direct contact with cathode active materials (CAMs), in particular at high potentials during charging. [2,[26][27][28] Several years ago, Takada summarized the early work on SSBs and described the need for coatings against the formation of space charge layers at the interface between high-voltage cathodes and thiophosphate SEs. [29] Haruyama et al. concluded from density functional theory calculations that space charge layers between LiCoO 2 (LCO) and thiophosphate-based SEs are responsible for high impedances and that the addition of a buffer layer reduces such effects. [30] However, experimental evidence for such claims has not yet been reported. While these considerations are certainly valuable, from a current perspective, effects arising from the space charge layer are likely overstated and the role of oxidative degradation of the SE is understated. [31] Though the The last decade has seen considerable advancements in the development of solid electrolytes for solid-state battery applications, with particular attention being paid to sulfide superionic conductors. Importantly, the intrinsic electrochemical instability of these high-performance separators highlights the notion that further progress in the field of solid-state batteries is contingent on the optimization of component material interfaces in order to se...

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Section: Figurementioning

confidence: 99%

On the Functionality of Coatings for Cathode Active Materials in Thiophosphate‐Based All‐Solid‐State Batteries

Culver

Koerver

Zeier

et al. 2019

Advanced Energy Materials

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253

309

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“…Future research should clearly be focused on enhancing the electronic stability of materials to better protect them from, e.g., lattice oxygen loss. The longevity of cells using high-Ni NCM CAMs is found to be greatly improved by the presence of surface oxide [246][247][248][249][250][251] or phosphate coatings. The most promising approaches are certainly: i) doping and ii) surface modification, as well as iii) implementing concentration gradients.…”

Section: Summary and Perspectivementioning

confidence: 99%

“…[245] Furthermore, targeted protection through surface coating seems to be a promising approach to counteract electrolyte decomposition and formation of rock-salt-type or spinel phases. The longevity of cells using high-Ni NCM CAMs is found to be greatly improved by the presence of surface oxide [246][247][248][249][250][251] or phosphate coatings. [252][253][254][255][256] Also, molecular surface functionalization using organophosphates can apparently successfully reduce transition-metal dissolution, thereby positively affecting the cell cyclability.…”

Section: Summary and Perspectivementioning

confidence: 99%

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

et al. 2019

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costs are required. Current state-of-theart LIBs using, e.g., well-established LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM111) cathode material are yet not able to fulfill all these demands. In order to increase the energy density of LIBs, battery produ cers and researchers pursue various strategies. Substitution of expensive Co by Ni to achieve LiNi 1−x−y Co x Mn y O 2 compounds with x < 0.3 in order to increase the structural stability at high state-of-charge (SOC) is one possible approach. Another promising material class is represented by Li-rich high-energy NCM (HE-NCM) materials (cLi 2 MnO 3 ⋅[1 − c]LiTMO 2 [TM = Ni, Co, Mn, etc.]). All of these subgroups of layered oxides have in common a crystal structure that is prone to irreversible changes and fatigue during continuous Li (de-)intercalation. The relevant changes in electronic and crystal structure strongly depend on the particular cathode composition and micro/nanostructure. The development of a target-oriented roadmap to improved LIBs that meet the above requirements must address the underlying mechanisms on different cell levels, i.e., from the atomic level to the electrode level. A comprehensive summary of the properties and developments in the field of Ni-rich NCM [1][2][3][4][5][6][7][8][9] and Li-rich HE-NCM [10][11][12][13][14][15][16] has been presented recently In order to satisfy the energy demands of the electromobility market, both Ni-rich and Li-rich layered oxides of NCM type are receiving much attention as high-energy-density cathode materials for application in Li-ion batteries. However, due to different stability issues, their longevity is limited. During formation and continuous cycling, especially the electronic and crystal structure suffers from various changes, eventually leading to fatigue and mechanical degradation. In recent years, comprehensive battery research has been conducted at Karlsruhe Institute of Technology, mainly aiming at better understanding the primary degradation processes occurring in these layered transition metal oxides. The characteristic process of formation and mechanisms of fatigue are fundamentally characterized and the effect of chemical composition on cell chemistry, electrochemistry, and cycling stability is addressed on different length scales by use of state-of-the-art analytical techniques, ranging from "standard" characterization tools to combinations of advanced in situ and operando methods. Here, the results are presented and discussed within a broader scientific context. by several authors. Here, we focus on the detailed characterization of these materials on different length scales, including the processes during formation and fatigue.After a brief introduction of the different materials addressed here, their characteristic process of formation and mechanisms of fatigue are discussed with respect to cell chemistry, electrochemistry, and cycling stability. Based on the fundamental results of our experimental studies on the material level, the effect of formation and fatigue on different cell levels is evalu...

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“…Now that the parasitic side reactions start from the interfaces between the solid cathodes and liquid electrolytes, the most effective method is to avoid their direct contact by introducing passive physical protection layer on the cathode surface . In general, the employed coating species can be categorized into i) the chemically and electrochemically inactive coatings, including metal oxides (Al 2 O 3 , TiO 2 , MgO, SiO 2 , ZrO 2 , V 2 O 5 , Nb 2 O 5 , ZnO, MoO 3 , and Y 2 O 3 ,) and phosphates (AlPO 4 , MnPO 4 , Mn 3 (PO 4 ) 2 , La(PO 4 ) 3 , Ni 3 (PO 4 ) 2 , Co 3 (PO 4 ) 2 , ZrP 2 O 7 , and FePO 4 ) as well as some fluorides (AlF 3 and LiF); ii) the Li + conductive coatings, mainly refer to the Li‐containing compounds such as LiAlO 2 , Li 2 ZrO 3 , Li 3 VO 4 , Li 2 MnO 3 , LiMn 2 O 4 , Li 3 PO 4 (LPO), LiFePO 4 (LFP), LiMnPO 4 , Li 2 TiO 3 , LiTiO 2 , Li 2 O‐2B 2 O 3 , LiTi 2 (PO 4 ) 3 , LiZr 2 (PO 4 ) 3 , Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 , Li 0.5 La 0.5 TiO 3 , LiTaO 3 , Li 4 SiO 4 , and LiAlF 4 as well as some heterostructured electrochemical active cathodes (Li 1.2 Ni 0.2 Mn 0.6 O 2 , Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 and NCM333); and iii) the electron conducting coating, representatively, reduced graphene oxide (rGO), permeable poly (3,4‐ethylenedioxythiophene) (PEDOT),…”

Section: Strategies To Mitigate the Surface/interface Structure Degramentioning

confidence: 99%

Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies

Liang

Zhang

Zhao

et al. 2019

Adv Materials Inter

151

111

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Nickel‐rich layered transition‐metal oxides with high‐capacity and high‐power capabilities are established as the principal cathode candidates for next‐generation lithium‐ion batteries. However, several intractable issues such as the poor thermal stability and rapid capacity fade as well as the air‐sensitivity particularly for the Ni content over 80% have seriously restricted their broadly practical applications. The properties and nature of the stable surface/interface, where the Li+ shuttles back and forth between the cathode and electrolyte, play a significant role in their ultimate lithium‐storage performance and industrial processability. Thus, tremendous efforts are made to in‐depth understanding of the essential origins of surface/interface structure degradation and efficient surface modification methodologies are intensively explored. The purpose of the contribution is first to provide a comprehensive review of the up‐to‐date mechanisms proposed to rationally elucidate the surface/interface behaviors, and then, focus on recent developed strategies to optimize the surface/interface structure and chemistry including synthetic condition regulation, surface doping, surface coating, dual doping‐coating modification, and concentration‐gradient structure as well as electrolyte additives. Finally, the perspective on future research trends and feasible approaches toward advanced Ni‐rich cathodes with stable surface/interface is presented briefly.

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Room temperature, liquid-phase Al₂O₃ surface coating approach for Ni-rich layered oxide cathode material

Abstract: Solution-based trimethylaluminum treatment of NCM811 cathode material leads to drying and coating in a single step and therefore improved cycling performance.

Cited by 90 publications

References 20 publications

On the Functionality of Coatings for Cathode Active Materials in Thiophosphate‐Based All‐Solid‐State Batteries

On the Functionality of Coatings for Cathode Active Materials in Thiophosphate‐Based All‐Solid‐State Batteries

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

Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies

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Room temperature, liquid-phase Al2O3 surface coating approach for Ni-rich layered oxide cathode material

Abstract: Solution-based trimethylaluminum treatment of NCM811 cathode material leads to drying and coating in a single step and therefore improved cycling performance.

Cited by 90 publications

References 20 publications

On the Functionality of Coatings for Cathode Active Materials in Thiophosphate‐Based All‐Solid‐State Batteries

On the Functionality of Coatings for Cathode Active Materials in Thiophosphate‐Based All‐Solid‐State Batteries

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

Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies

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Room temperature, liquid-phase Al₂O₃ surface coating approach for Ni-rich layered oxide cathode material