An Abnormal 3.7 Volt O3‐Type Sodium‐Ion Battery Cathode

Wang, Peng Fei; Xin, Hanshen; Zuo, Tong‐Tong; Li, Qinghao; Yang, Xinan; Yin, Ya‐Xia; Gao, Xike; Yu, Xiqian; Guo, Yu‐Guo

doi:10.1002/anie.201804130

Cited by 124 publications

(84 citation statements)

References 26 publications

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“…The reversible phenomena were observed on discharge (Figure b). It is notable that the volume change was only 1.45% between the fresh state and the electrode charged to 4.3 V; this is the first time such a minimal variation in volume has been reported for O3‐, P2‐, or P′2‐type layered cathode materials, to the best of our knowledge. The operando SXRD data confirmed that the original P′2 phase was maintained during charge and discharge.…”

Section: Resultsmentioning

confidence: 57%

A New Strategy to Build a High‐Performance P′2‐Type Cathode Material through Titanium Doping for Sodium‐Ion Batteries

Park

Choi

et al. 2019

Adv Funct Materials

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1901912 (1 of 10) Herein, Ti 4+ in P′2-Na 0.67 [(Mn 0.78 Fe 0.22 ) 0.9 Ti 0.1 ]O 2 is proposed as a new strategy for optimization of Mn-based cathode materials for sodium-ion batteries, which enables a single phase reaction during de-/sodiation. The approach is to utilize the stronger Ti-O bond in the transition metal layers that can suppress the movements of Mn-O and Fe-O by sharing the oxygen with Ti by the sequence of Mn-O-Ti-O-Fe.It delivers a discharge capacity of ≈180 mAh g −1 over 200 cycles (86% retention), with S-shaped smooth charge-discharge curves associated with a small volume change during cycling. The single phase reaction with a small volume change is further confirmed by operando synchrotron X-ray diffraction. The low activation barrier energy of ≈541 meV for Na + diffusion is predicted using first-principles calculations. As a result, Na 0.67 [(Mn 0.78 Fe 0.22 ) 0.9 Ti 0.1 ]O 2 can deliver a high reversible capacity of ≈153 mAh g −1 even at 5C (1.3 A g −1 ), which corresponds to ≈85% of the capacity at 0.1C (26 mA g −1 ). The nature of the sodium storage mechanism governing the ultrahigh electrode performance in a full cell with a hard carbon anode is elucidated, revealing the excellent cyclability and good retention (≈80%) for 500 cycles (111 mAh g −1 ) at 5C (1.3 A g −1 ).reactions. [3][4][5] Although SIBs have intrinsic drawbacks, such as their low operation voltages relative to those of LIBs and the difficulty of ready insertion of sodium ions because of the larger size of Na + ions (1.02 Å) compared with Li + ions (0.76 Å), these difficulties can be mitigated with a high capacity to compensate for the low operation voltage. [5] Layered cathode material for SIBs (Na x MeO 2 ) has received particular attention owing to their relatively high capacity and structural stability. Layered Na x MeO 2 (x = 0.5-1 and Me; transition metal) consist of MeO 2 layers sharing edges with MeO 6 octahedra were classified into two groups based on structure: trigonal prismatic (P type: P2, P3, and P′2) and octahedral (O type: O3). [6] The differences in these structures are attributed to sodium ions being respectively located at the district trigonal prismatic or octahedral crystallographic sites sandwiched between the MeO 2 sheets. Among them, many works have introduced Mn-based cathode materials, mainly P2-type materials, in which sodium ions are located at prismatic sites with an AABB oxygen stacking sequence, because of their low cost, good performance, and nontoxicity. [7,8] Recently, many works about P2-type materials have been investigated such as Na x MnO 2 , [7,9] Na x CoO 2 , [10] Na x VO 2 , [11] Na x [Ni,Mn] O 2 , [12] Na x [Fe,Mn]O 2 , [13] Na x [Ni,Fe,Mn]O 2 , [14] Na x [Mg,Mn] O 2 , [15] Na x [Ni,Mg,Mn]O 2 . [16] P2-type materials crystallize in a hexagonal structure; however, the transition metal layers can be distorted at higher temperature with stabilization in an orthorhombic structure (represented as P′2) albeit with the same chemical composition. [17,18] Many works have introduced Mn-based c...

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Section: Resultsmentioning

confidence: 57%

A New Strategy to Build a High‐Performance P′2‐Type Cathode Material through Titanium Doping for Sodium‐Ion Batteries

Park

Choi

et al. 2019

Adv Funct Materials

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“…Exploiting a new cathode material with satisfactory characteristics is therefore a critical challenge. [ 5 ] Currently, different types of cathode materials, including transition metal oxides, [ 6 ] polyanion phosphides, [ 7 ] and hexacyanoferrate derivatives, [ 8 ] have been widely investigated. Among them, the layered metal oxides with their high output voltage and relatively simple synthetic route have become the most promising candidates for SIBs.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Enhanced Cycle and Rate Performances of the F‐Substituted P2‐Type Oxide Cathodes for Sodium‐Ion Batteries

Tan

Moon

et al. 2020

Advanced Energy Materials

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A series of F‐substituted Na2/3Ni1/3Mn2/3O2−xFx (x = 0, 0.03, 0.05, 0.07) cathode materials have been synthesized and characterized by solid‐state 19F and 23Na NMR, X‐ray photoelectron spectroscopy, and neutron diffraction. The underlying charge compensation mechanism is systematically unraveled by X‐ray absorption spectroscopy and electron energy loss spectroscopy (EELS) techniques, revealing partial reduction from Mn4+ to Mn3+ upon F‐substitution. It is revealed that not only Ni but also Mn participates in the redox reaction process, which is confirmed for the first time by EELS techniques, contributing to an increase in discharge specific capacity. The detailed structural transformations are also revealed by operando X‐ray diffraction experiments during the intercalation and deintercalation process of Na+, demonstrating that the biphasic reaction is obviously suppressed in the low voltage region via F‐substitution. Hence, the optimized sample with 0.05 mol f.u.−1 fluorine substitution delivers an ultrahigh specific capacity of 61 mAh g−1 at 10 C after 2000 cycles at 30 °C, an extraordinary cycling stability with a capacity retention of 75.6% after 2000 cycles at 10 C and 55 °C, an outstanding full battery performance with 89.5% capacity retention after 300 cycles at 1 C. This research provides a crucial understanding of the influence of F‐substitution on the crystal structure of the P2‐type materials and opens a new avenue for sodium‐ion batteries.

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“…However, upon charging, the originally occupied edge‐sharing MO 6 octahedral sites would slowly change to prismatic sites, which transforms the material from O3 to P3 phase and generates Na + vacancies. Such phase transformation leads to voltage fading in most Na x MO 2 and reduces the energy density with nearly half of the capacity lost . Study by Komaba et al on Na 1−x Ni 0.5 Mn 0.5 O 2 suggests that the O3‐NaNi 0.5 Mn 0.5 O 2 undergoes a phase transformation from O3, O′3, P3, P′3 to P3″ during the Na + extraction process ( Figure a,b) in the voltage window of 2.0–4.5 V (vs Na/Na + ) .…”

Section: Sibsmentioning

confidence: 93%

Layer‐Based Heterostructured Cathodes for Lithium‐Ion and Sodium‐Ion Batteries

Deng

Liang

et al. 2019

Adv Funct Materials

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A critical bottleneck that hinders major performance improvement in lithium-ion and sodium-ion batteries is the inferior electrochemical activity of their cathode materials. While significant research progresses have been made, conventional single-phase cathodes are still limited by intrinsic deficiencies such as low reversible capacity, enormous initial capacity loss, rapid capacity decay, and poor rate capability. In the past decade, layer-based heterostructured cathodes acquired by combining multiple crystalline phases have emerged as candidates with a huge potential to realize performance breakthrough. Herein, recent studies on the structural properties, electrochemical behaviors, and synthesis route optimizations of these heterostructured cathodes are summarized for in-depth discussions. Particular attention is paid to the latest mechanism discoveries and performance achievements. This review thus aims to promote a deeper understanding of the correlation between the crystal structure of cathodes and their electrochemical behavior, and offers guidance to design advance cathode materials from the aspect of crystal structure engineering.

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An Abnormal 3.7 Volt O3‐Type Sodium‐Ion Battery Cathode

Cited by 124 publications

References 26 publications

A New Strategy to Build a High‐Performance P′2‐Type Cathode Material through Titanium Doping for Sodium‐Ion Batteries

A New Strategy to Build a High‐Performance P′2‐Type Cathode Material through Titanium Doping for Sodium‐Ion Batteries

Insights into the Enhanced Cycle and Rate Performances of the F‐Substituted P2‐Type Oxide Cathodes for Sodium‐Ion Batteries

Layer‐Based Heterostructured Cathodes for Lithium‐Ion and Sodium‐Ion Batteries

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