Unprecedented Superhigh‐Rate and Ultrastable Anode for High‐Power Battery via Cationic Disordering

Abstract

capacities and low lithiation potentials approaching 0 V versus Li/Li + are favored for high-energy applications. [3] Their specific capacities decrease drastically when they are charged and discharged at high rates. For example, the specific capacity of graphite drops from 350 mAh g −1 at 0.2 C to 50 mAh g −1 at 2 C. [4] In addition, their sluggish interfacial kinetics and large spatial overpotential inhomogeneities under fast-charging conditions lead to undesirable plating of the Li dendrites on the electrode surface, [5] which may result in short circuits and thermal runaway. [6] To address this issue, Li 4 Ti 5 O 12 (LTO), which exhibits superior structural stability at high rates, is currently used as an anode in high-power LIBs. [7] The LTO can maintain high stability even when charged and discharged at 50 C. [8] However, in comparison to graphite, the low theoretical capacity (175 mAh g −1 ) and high lithiation potential (1.55 V versus Li/Li + ) of LTO results in a considerably lower energy density of the battery. [9] Therefore, a significant amount of energy density must be sacrificed to achieve high power density in the LIBs. [1a] In recent years, a series of niobium-based anode materials, such as the TiNb 2 O 7 (TNO), [10] Ti 2 Nb 10 O 29 , [11] Nb 16 W 5 O 55 , [5a] and Nb 2 O 5 , [12] have been reported as alternatives to LTO. Among them, TNO is the most promising candidate because of its similar lithiation potential (1.64 V versus Li/Li + ) and considerably higher theoretical capacity (387 mAh g −1 ) than that of LTO. The layered monoclinic structure of the TNO, which consists High-power lithium-ion batteries (LIBs) are critical for power-intensive applications; however, their development is largely hindered by the lack of anode materials that have stability and high capacity at high charging/discharging rates. Herein, a cationic disordering strategy is reported to build an ideal high-power anode with boosted intercalation kinetics and a stable framework. A novel titanium niobate (TiNb 2 O 7 ) anode with unique predistorted Nb(Ti) O 6 octahedrons (pd-TNO) is developed by introducing cation disorder, which allows ultrafast Li + storage within seconds and exceptional stability over long cycling at high rates. The pd-TNO delivers an outstanding specific capacity of 153 mAh g −1 at 100 C, 20 times higher than that of conventional TNO anodes without cationic disordering, and retains 42.8% of the capacity after 15,000 cycles. Using the pd-TNO anode, a high-power LIB with an unprecedented power density of 91,197 W kg −1 at 200 C, which is approximately eight times higher than that of the advanced commercial high-power anode Li 4 Ti 5 O 12 (11,813 W kg −1 at 50 C), is demonstrated. Importantly, the pd-TNO is prepared under ambient conditions via a high-throughput process, and it exhibits considerable potential for scalability for practical applications.

Crystallographic Insight of Reduced Lattice Volume Expansion in Mesoporous Cu2+‐Doped TiNb2O7 Microspheres during Li+ Insertion

“…Modification of TiNb 2 O 7 via surface coating with electronically conductive carbon has been widely used to accelerate the Li + transport kinetics of electrodes. [20][21][22][23][24][25][26][27] Furthermore, bulk doping with V 5+ and Mo 6+ have been reported to improve the intrinsic ionic conductivity of TiNb 2 O 7 in order to facilitate the Li + diffusion rate in the crystal lattices. [28,29] However, the state and location of dopants in TiNb 2 O 7 are still unclear up to now.…”

A Paradigm of Calendaring‐Driven Electrode Microstructure for Balanced Battery Energy Density and Power Density

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phase material with a monoclinic system (space group C2/m), TiNb 2 O 7 possesses a stable Li + diffusion channel structure constructed by ReO 3 -like regions (blocks) of corner-and edge-shared octahedra, and displays highly stable electrochemical lithium extraction/insertion behavior (Figure S1, Supporting Information). [11][12][13][14][15] TiNb 2 O 7 exhibits a comparable lithiation potential slope between 1-2 V (≈1.5 V on average, vs Li + /Li) to Li 4 Ti 5 O 12 , which is widely considered a good fastcharging battery anode (Figure 1a). [16][17][18][19] Also, it delivers a theoretical capacity of 387.6 mAh g −1 , which is over double that of Li 4 Ti 5 O 12 and slightly higher than mostly used graphite anode in commercial lithium-ion batteries.

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Mutual Self-Regulation of d-Electrons of Single Atoms and Adjacent Nanoparticles for Bifunctional Oxygen Electrocatalysis and Rechargeable Zinc-Air Batteries

“…Rechargeable zinc-air batteries (ZABs), which convert chemicals into electrochemical energy through oxygen reduction and evolution reactions (ORR and OER), are an important technique with great promise in the future energy system due to their high energy density and excellent safety. The ORR/OER reactions are generally kinetically sluggish and require a large overpotential, resulting in unsatisfying power density and poor durability of this device [1][2][3][4][5][6][7]. These reactions are conventionally accelerated by precious metal-based catalysts such as Pt (for ORR), Ru, and Ir (for OER).…”