Intercalation-type MoNb12O33 with a porous-microspherical nanoarchitecture is explored as the first molybdenum niobium oxide anode material for Li+ storage.

Tungsten-free and niobium-rich Al0.5Nb24.5O62 with an intercalated nature is explored as a new and practical anode material for high-performance lithium-ion storage.

some issues, such as insufficient battery longevity, safety risks, and limited driving ranges/speeds. [1] Thus, high-performance LIBs with long-term cycle life, good safety, and high energy/power densities are pursued. Particularly, the cycle life is essential in actual applications. Capacity decay of LIBs primarily derives from the fact that electrode materials generally suffer mechanical stresses since the strains associated with phase transitions or lattice-parameter variations during Li + insertion-extraction are generally obvious. Mismatched lattice parameters between dominated and coexisting phases in two-phase reactions or large unitcell volume variations in solid-solution reactions can lead to the fracture phase interfaces, thus significantly contributing to the capacity decay. These issues can be completely avoided in "zero-strain" electrode materials whose unit-cell volume variations are negligible (<1%) during discharging-charging. Spinel Li 4 Ti 5 O 12 , a typical "zero-strain" anode material, has been demonstrated for thousands cycles in LIBs. This excellent cycling stability stems from its tiny volume variation (≈0.2%) upon cycling. [2] Other "zero-strain" anode materials, such as LiCrTiO 4 and LiY(MoO 4 ) 2 , also present decent cycling stability. [3] Clearly, "zero-strain" materials are ideal for a long operational energy storage. To the best of our knowledge, however, the very limited "zero-strain" anode materials explored for LIBs so far commonly present small reversible capacities "Zero-strain" compounds are ideal energy-storage materials for long-term cycling because they present negligible volume change and significantly reduce the mechanically induced deterioration during charging-discharging. However, the explored "zero-strain" compounds are very limited, and their energy densities are low. Here, γ phase Li 3.08 Cr 0.02 Si 0.09 V 0.9 O 4 (γ-LCSVO) is explored as an anode compound for lithium-ion batteries, and surprisingly its "zero-strain" Li + storage during Li + insertion-extraction is found through using various state-of-the-art characterization techniques. Li + sequentially inserts into the 4c(1) and 8d sites of γ-LCSVO, but its maximum unitcell volume variation is only ≈0.18%, the smallest among the explored "zero-strain" compounds. Its mean strain originating from Li + insertion is only 0.07%. Consequently, both γ-LCSVO nanowires (γ-LCSVO-NW) and micrometer-sized particles (γ-LCSVO-MP) exhibit excellent cycling stability with 90.1% and 95.5% capacity retention after as long as 2000 cycles at 10C, respectively. Moreover, γ-LCSVO-NW and γ-LCSVO-MP respectively deliver large reversible capacities of 445.7 and 305.8 mAh g −1 at 0.1C, and retain 251.2 and 78.4 mAh g −1 at 10C. Additionally, γ-LCSVO shows a suitably safe operating potential of ≈1.0 V, significantly lower than that of the famous "zero-strain" Li 4 Ti 5 O 12 (≈1.6 V). These merits demonstrate that γ-LCSVO can be a practical anode compound for stable, high-energy, fast-charging, and safe Li + storage.The ORCID identificati...

M-Nb-O compounds are advanced anode materials for lithium-ion batteries (LIBs) due to their high specific capacities, safe operating potentials, and high cycling stability. Nevertheless, the found M-Nb-O anode materials are very limited. Here, MgNbO is developed as a new M-Nb-O material. MgNbO porous microspheres (MgNbO-P) with primary-particle sizes of 30-100 nm are fabricated based on a solvothermal method. MgNbO has an open 3 × 4 × ∞ Wadsley-Roth shear structure and a large unit-cell volume, leading to its largest Li diffusion coefficients among all the developed M-Nb-O anode materials. In situ X-ray diffraction analyses reveal its high structural stability and intercalating characteristic. These architectural, conductivity, and structural advantages in MgNbO-P lead to its most significant intercalation pseudocapacitive contribution (87.7% at 1.1 mV s) among the existing M-Nb-O anode materials and prominent rate capability (high reversible capacities of 338 mAh g at 0.1C and 230 mAh g at 10C). Additionally, this new material exhibits a safe operating potential (∼1.68 V), an ultrahigh initial Coulombic efficiency (94.8%), and an outstanding cycling stability (only 6.9% capacity loss at 10C over 500 cycles). All of these evidences indicate that MgNbO-P is an ideal anode material for high-energy, safe, fast-charging, and stable LIBs.

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Conductive Nb12O29 hierarchical microspheres with nanosheet shells demonstrated comprehensively good electrochemical properties, including a significant pseudocapacitive contribution, safe operating potential, high reversible capacity, superior initial coulombic efficiency, increased rate capability, and durable cycling stability.

The oxide perovskite family holds great promise for diverse applications on account of their unique chemical and physical properties. However, owing to the inadequate Li + -storage sites, the insertion-type perovskite anodes for lithium-ion batteries (LIBs) are limited. A-site deficient perovskites with rich intrinsic vacancies and ion transport channels are believed to be the desirable hosts of superior Li + storage. Herein, the perovskite Li 0.1 La 0.3 NbO 3 (LLNO) is designed and demonstrated as the remarkable anode for LIBs with a high specific capacity, a safe operating voltage, an excellent rate performance, and a long cycling life. More importantly, the outstanding cycling stability of LLNO is originated from its low strain characteristic with a maximum volume change of only 1.17%. The exceptional rate performance can be explained by the unconventional Li + transport pathways with external → grain boundaries → lattice deficiencies. These results not only reveal that A-site deficient perovskite LLNO is a promising anode for LIBs but also provide fundamental insights into the Li + ions transport mechanism, facilitating the development of high-performance perovskite anodes.

Zero-strain" materials with little lattice strain and volume change during long-term cycling are ideal electrode choices for long-life lithium-ion batteries. However, the very limited "zero-strain" materials explored generally show small capacities (<200 mAh g −1 ), and the origin of "zero-strain" is still unclear. Here, Na 2 Ca(VO 3 ) 4 (NCVO) nanowires are explored as a new anode material capable of keeping single-phase-transition "zero-strain" during large-capacity (381 mAh g −1 ) Li + intercalation. NCVO owns a crystal structure with isolated [V 4 O 12 ] 4− tetracycles separated by large-sized NaO 6 octahedra and CaO 8 square antiprism decahedra, generating large-sized quadrilateral and hexagonal channels (≈3.6 Å). During lithiation, two-electron transfer per vanadium is accomplished, introducing a large amount of Li + into interstitial sites and increasing the size of reduced vanadium ions. The former and latter expansion effects are eliminated by the superior volume-buffering capabilities of the sufficiently large interstitial sites and electrochemical inactive Na-/Ca-based polyhedra, respectively, thus achieving "zero-strain" with the maximum volume variation of only 0.039% and mean strain of only 0.060%. Therefore, the NCVO nanowires exhibit exceptional cyclic stability, as demonstrated by 93.8%/93.2%/94.7% capacity retention over 2000/2000/7000 cycles at 1C/2C/10C. The understanding of the crystal-structural features for "zero-strain" provides a guide for the future designs of "zero-strain" energy-storage materials.