Structural and Electrochemical Kinetic Properties of 0.5Li2MnO3∙0.5LiCoO2 Cathode Materials with Different Li2MnO3 Domain Sizes

Kaewmala, Songyoot; Limphirat, Wanwisa; Yordsri, Visittapong; Kim, Hyunwoo; Muhammad, Shoaib; Yoon, Won‐Sub; Srilomsak, Sutham; Limthongkul, Pimpa; Meethong, Nonglak

doi:10.1038/s41598-018-36593-9

Cited by 38 publications

(22 citation statements)

References 60 publications

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“…Controlled structural/chemical changes induced by the Li‐TM inter‐diffusion between the two phases in the Li‐rich materials can help to fully exploit oxygen redox reaction in addition to TM redox reaction, resulting in very high energy density. Given the Li‐rich layered materials that are composed of the two layered phases, [ 3b,10a,14b,21 ] the Li‐TM inter‐diffusion between both phases can lead to different composite structure such as the excess Li and Ni incorporation in both layered phases that can remarkably improve reversible oxygen redox activity and layered structure stability. The excess Li in the both layered phases can increase local Li‐rich environments such as Li–O–Li structures leading to the formation of available additional electronic states nearby the oxygen orbital that can activate and increase the oxygen redox reaction.…”

Section: Resultsmentioning

confidence: 99%

Fully Exploited Oxygen Redox Reaction by the Inter‐Diffused Cations in Co‐Free Li‐Rich Materials for High Performance Li‐Ion Batteries

et al. 2020

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To meet the growing demand for global electrical energy storage, high‐energy‐density electrode materials are required for Li‐ion batteries. To overcome the limit of the theoretical energy density in conventional electrode materials based solely on the transition metal redox reaction, the oxygen redox reaction in electrode materials has become an essential component because it can further increase the energy density by providing additional available electrons. However, the increase in the contribution of the oxygen redox reaction in a material is still limited due to the lack of understanding its controlled parameters. Here, it is first proposed that Li‐transition metals (TMs) inter‐diffusion between the phases in Li‐rich materials can be a key parameter for controlling the oxygen redox reaction in Li‐rich materials. The resulting Li‐rich materials can achieve fully exploited oxygen redox reaction and thereby can deliver the highest reversible capacity leading to the highest energy density, ≈1100 Wh kg−1 among Co‐free Li‐rich materials. The strategy of controlling Li/transition metals (TMs) inter‐diffusion between the phases in Li‐rich materials will provide feasible way for further achieving high‐energy‐density electrode materials via enhancing the oxygen redox reaction for high‐performance Li‐ion batteries.

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Section: Resultsmentioning

confidence: 99%

Fully Exploited Oxygen Redox Reaction by the Inter‐Diffused Cations in Co‐Free Li‐Rich Materials for High Performance Li‐Ion Batteries

et al. 2020

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“…[64] Previous studies showed that lithium extraction in Li 2 MnO 3 with a large domain size is more difficult than in a small domain, and more Li 2 MnO 3 components are activated in the latter during cycling. [7,65] However, the irreversible phase transition from Li 2 MnO 3 to LiMn 2 O 4 and the induced defects hinder lithium diffusion. As a result, the lithium ion mobility of an Li 2 MnO 3 sample with large domain size delivered a superior rate performance than the small domain during prolonged cycles.…”

Section: Poor Rate Performance and Impact On Fast Chargingmentioning

confidence: 99%

Challenges and Recent Advances in High Capacity Li‐Rich Cathode Materials for High Energy Density Lithium‐Ion Batteries

et al. 2021

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mismatch between the cathode and anode materials (the cathode capacity is nearly an order of magnitude smaller than the anode capacity) has seriously hindered the development of LIBs. [2] Li-rich cathode materials have been regarded as one of the most promising candidates for next-generation cathode materials for rechargeable LIBs owing to their prominent specific capacity. For instance, in Li-rich Mn-based (LRM) cathode materials with the chemical formula xLi 2 MnO 3 ⋅(1 -x)LiTMO 2 (TM = Ni, Mn, Co, etc.), when x = 0.5, in the form of Li 1.2 Mn 0.54 Co 0.13 Ni 0.13 O 2 , the theoretical capacity of the LRM cathode reaches over 250 mA h g −1 for 1 Li + extraction, and ≈378 mA h g −1 for 1.2 Li + extraction. [3] Furthermore, LRM cathodes reduce the use of expensive Co and have the advantages of low cost, environmental friendliness, and high thermal stability. However, LRM cathode materials have inherent issues, such as low initial Coulombic efficiency (ICE), poor rate capacity, and serious voltage fading, which inhibit their further practical applications. [4] These issues need to be immediately addressed to eliminate range and safety anxiety in the electric consumption market. The development of state-of-the-art characterization techniques has brought new understandings of the origins of these problems. [5] In this case, considerable progress has been made in the evolution of LRM cathode structures and its various reaction mechanisms during long-time cycles, the electrochemical activity of anions, and other aspects. In addition, significant advances have also been made in the novel modification methods for promoting the electrochemical performances of LRM cathode materials as well as other branches of Li-rich cathode materials. Herein, we present a comprehensive review of the recent challenges and prospects in high-capacity Li-rich cathode materials. This paper aims to offer a global and critical perspective on Lirich cathode materials for LIBs, as shown in Figure 1, including an in-depth evaluation of degradation mechanisms, the prevailing modification methods and development trends, application, and future opportunities for LRM electrode materials in full-cells and future solid-state batteries. We intend to provide perspectives on the practical development and application of Li-rich cathode materials have attracted increasing attention because of their high reversible discharge capacity (>250 mA h g −1 ), which originates from transition metal (TM) ion redox reactions and unconventional oxygen anion redox reactions. However, many issues need to be addressed before their practical applications, such as their low kinetic properties and inefficient voltage fading. The development of cutting-edge technologies has led to cognitive advances in theory and offer potential solutions to these problems. Herein, a recent in-depth understanding of the mechanisms and the frontier electrochemical research progress of Li-rich cathodes are reviewed. In addition, recent advances associated with various strategies to promot...

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“…When the GITT technique is used, the cell is charged with a constant current of 5.6 mA/g (C/50 rate) for 1 h and then relaxed for 2 h to reach a near-equilibrium state; this process is then repeated until the final cut-off voltage is reached. During the 1st charge, both samples showed increased polarization in the voltage range >4.5 V or >125 mAh/g, where the oxygen redox reaction is mainly attributed (Figure f). ,, However, the polarization above 4.5 V during the 1st charge is much lower in the CD sample than in the LCD sample (upper, Figure f); this difference indicates that a facile oxygen redox reaction in the CD sample occurs even after almost full extraction of Li. Similarly, the polarization <3.5 V or >125 mAh/g during the 1st discharge process, in which a charge compensation mainly occurs in the oxygen redox reaction, ,, is much lower in the CD sample than in the LCD sample (lower, Figure f).…”

Section: Resultsmentioning

confidence: 97%

“…However, in the 2nd cycle, the contribution of the oxygen redox reaction is much lower than that in the 1st cycle; this change indicates a decrease in the oxygen redox activity. The oxygen redox reaction in 3d-TM-based Li-rich layered materials occurs mainly in the M phase, which has excess Li; − therefore, the low oxygen redox activity during the 2nd cycle in the LCD sample may be a result of the irreversible structural change during the 1st cycle.…”

Section: Resultsmentioning

confidence: 99%

Superior Rate Capability and Cycling Stability in Partially Cation-Disordered Co-Free Li-Rich Layered Materials Enabled by an Initial Activation Process

et al. 2021

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Li-rich layered materials that have Co-free and Mnrich 3d-transition metals have the potential to increase the achievable energy density of batteries because they are inexpensive and yield high capacity by exploiting an additional oxygen redox reaction. However, these have low electrochemical activity and sustainability, with severe voltage fade, rapid capacity decay, and poor rate capability. Here, we report sustainable cycling stability and fast rate capability of Co-free Li2MnO3-based Li-rich layered materials that are governed by the electrochemical activation process during the 1st cycle and that this process can be controlled by the degree of the cation disordering in the pristine material. From the comparative study of two samples that have different degrees of cation disordering in the same composition, an increase in cation disordering in the pristine material strongly improves its tolerance to structural changes in the bulk and on the surface during the activation process at the 1st cycle, leading to less structural changes for subsequent cycles. As a result, high electrochemical activity and superior rate capability in subsequent cycles can be achieved even with the cation disordering in the pristine. Furthermore, we verified the findings by developing an additional material that had higher cation disordering in the pristine structure than the samples tested and showing that the additional sample has improved rate capability and cycle retention. This understanding that sustainable electrochemical characteristics are governed by an activation process in the 1st cycle, which can be controlled by a structural feature of the pristine material, will be useful in the design of low-cost, Li-rich layered materials that can achieve sustainable high energy density and fast rate capability for Li-ion batteries.

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Structural and Electrochemical Kinetic Properties of 0.5Li2MnO3∙0.5LiCoO2 Cathode Materials with Different Li2MnO3 Domain Sizes

Cited by 38 publications

References 60 publications

Fully Exploited Oxygen Redox Reaction by the Inter‐Diffused Cations in Co‐Free Li‐Rich Materials for High Performance Li‐Ion Batteries

Fully Exploited Oxygen Redox Reaction by the Inter‐Diffused Cations in Co‐Free Li‐Rich Materials for High Performance Li‐Ion Batteries

Challenges and Recent Advances in High Capacity Li‐Rich Cathode Materials for High Energy Density Lithium‐Ion Batteries

Superior Rate Capability and Cycling Stability in Partially Cation-Disordered Co-Free Li-Rich Layered Materials Enabled by an Initial Activation Process

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