Advanced BaLi₂Ti₆O₁₄ Anode Fabricated via Lithium Site Substitution by Magnesium

Advanced Na- and Mg-doped BaLi₂Ti₆O₁₄ anodes in the form of BaLi_1.9M_0.1Ti₆O₁₄ (M = Na, Mg) are successfully fabricated and evaluated as lithium storage materials for rechargeable lithium-ion batteries. The effects of Na- and Mg-dopings on the crystal structure, surface morphology and electrochemical behavior are investigated for BaLi₂Ti₆O₁₄. The results show that both Na and Mg elements are successfully introduced into the Li site, and they do not alter the basic structure of BaLi₂Ti₆O₁₄. The resulting BaLi_1.9M_0.1Ti₆O₁₄ (M = Na, Mg) exhibit significant improvements on the electrochemical performance in terms of the rate capability and cycle performance. Especially for BaLi_1.9Mg_0.1Ti₆O₁₄, it can deliver an initial charge capacity of 111.7 mAh g^–1 at 5C. After 200 cycles, it still can maintain a reversible capacity of 90.1 mAh g^–1 with the capacity retention of 80.7%. The enhanced electrochemical properties can be attributed to the reduced particle size, decreased charge transfer resistance and enhanced ionic/electronic conductivity induced by Mg doping. Besides, in situ X-ray diffraction also reveals that BaLi_1.9Mg_0.1Ti₆O₁₄ has high structural stability and reversibility during charge/discharge process

Lithiation/Delithiation Behavior of Silver Nitrate as Lithium Storage Material for Lithium Ion Batteries

In this work, AgNO₃/CNTs composite is synthesized through a simple solution method. The morphology, electrochemical property, and lithium storage mechanism of AgNO₃/CNTs are thoroughly investigated and compared with bare AgNO₃. For AgNO₃, it can deliver an initial charge capacity of 552.3 mAh g^–1. After 100 cycles, AgNO₃ only retains a capacity of 84.5 mAh g^–1 with inferior capacity retention of 15.3%. In contrast, AgNO₃/CNTs composite presents the first charge capacity of 530.3 mAh g^–1 with capacity retention of 92.5% after 100 cycles (482.5 mAh g^–1). The enhanced performance can be ascribed to the introduction of carbon nanotube networks interlaced with AgNO₃ particles. Furthermore, the reaction mechanism of AgNO₃ with Li is also studied by various in situ and ex situ methods. It can be seen that the preliminary reaction between AgNO₃ and Li leads to the irreversible formation of LiNO₃, Li₃N, Li₂O, and Ag. With further reaction at low potentials, the resulting Ag reacts with Li to form Ag₃Li₁₀ alloys. Upon a reverse charge process, the lithium storage capacity is associated with the dealloying reaction of Ag₃Li₁₀ to the formation of Ag and Li. In the following cycles, the reversible capacity is maintained by Ag–Li alloying/dealloying reaction

LiCrTiO₄ Nanowires with the (111) Peak Evolution during Cycling for High-Performance Lithium Ion Battery Anodes

LiCrTiO₄ is a lithium insertion material that is isostructural with Li₄Ti₅O₁₂. Upon modification of its morphology, LiCrTiO₄ nanowires exhibit a high charge capacity of 154.6 mA h g^–1 at 100 mA g^–1, and this value can be maintained at 121.0 mA h g^–1 even at a high current density of 700 mA g^–1. Furthermore, the cycling performance shows that LiCrTiO₄ nanowires can also deliver a reversible capacity of 120.0 mA h g^–1 with 95.6% capacity retention of the first cycle after 550 cycles. The excellent electrochemical properties were revalidated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The most interesting feature in this work is the relationship between the periodic variation of the (111) peak intensities and the migration of lithium ions during cycling. This proves that LiCrTiO₄ nanowires are a zero-strain insertion material that can be a promising anode material for lithium ion batteries

Carbon-Enhanced Electrochemical Performance for Spinel Li₅Cr₇Ti₆O₂₅ as a Lithium Host Material

The design and facile fabrication of CrTi-based anode materials with long-life, good safety, and low cost are strongly desired for lithium-ion batteries. In this study, we adopt the sol–gel method using glucose as carbon source to synthesize carbon-coated Li₅Cr₇Ti₆O₂₅. The effects of a carbon layer in Li₅Cr₇Ti₆O₂₅/C on electrochemical properties are focused through comparing carbon-coated Li₅Cr₇Ti₆O₂₅ with carbon-free Li₅Cr₇Ti₆O₂₅. Electrochemical tests show that Li₅Cr₇Ti₆O₂₅/C possesses better cycling and rate performances than those of carbon-free Li₅Cr₇Ti₆O₂₅. Cycled at 500 mA g^–1, Li₅Cr₇Ti₆O₂₅/C delivers a high specific capacity of 111.6 mAh g^–1 with 13% capacity loss after 200 cycles. In contrast, Li₅Cr₇Ti₆O₂₅ only exhibits a specific capacity of 93.6 mAh g^–1 at 500 mA g^–1 with 19% capacity loss after 200 cycles. The preeminent electrochemical property of Li₅Cr₇Ti₆O₂₅/C is ascribed to the amorphous carbon coating layer. This carbon layer can remarkably facilitate the transportation of electrons and ions in Li₅Cr₇Ti₆O₂₅. Furthermore, the lithiation/delithiation behavior of Li₅Cr₇Ti₆O₂₅/C is also investigated by advanced in situ X-ray diffraction technique, and the results verify that Li₅Cr₇Ti₆O₂₅/C possesses a highly reversible structural change during the charge/discharge process

Sol–Gel Synthesis and in Situ X‑ray Diffraction Study of Li₃Nd₃W₂O₁₂ as a Lithium Container

In this work, garnet-framework Li₃Nd₃W₂O₁₂ as a novel insertion-type anode material has been prepared via a facile sol–gel method and examined as a lithium container for lithium ion batteries (LIBs). Li₃Nd₃W₂O₁₂ shows a charge capacity of 225 mA h g^–1 at 50 mA g^–1, and with the current density increasing up to 500 mA g^–1, the charge capacity can still be maintained at 186 mA h g^–1. After cycling at 500 mA g^–1 for 500 cycles, Li₃Nd₃W₂O₁₂ retains about 85% of its first charge capacity changed from 190.2 to 161 mA h g^–1. Furthermore, in situ X-ray diffraction technique is adopted for the understanding of the insertion/extraction mechanism of Li₃Nd₃W₂O₁₂. The full-cell configuration LiFePO₄/Li₃Nd₃W₂O₁₂ is also assembled to evaluate the potential of Li₃Nd₃W₂O₁₂ for practical application. These results show that Li₃Nd₃W₂O₁₂ is such a promising anode material for LIBs with excellent electrochemical performance and stable structure

Effect of Sodium-Site Doping on Enhancing the Lithium Storage Performance of Sodium Lithium Titanate

Via Li⁺, Cu²⁺, Y³⁺, Ce⁴⁺, and Nb⁵⁺ dopings, a series of Na-site-substituted Na_1.9M_0.1Li₂Ti₆O₁₄ are prepared and evaluated as lithium storage host materials. Structural and electrochemical analyses suggest that Na-site substitution by high-valent metal ions can effectively enhance the ionic and electronic conductivities of Na₂Li₂Ti₆O₁₄. As a result, Cu²⁺-, Y³⁺-, Ce⁴⁺-, and Nb⁵⁺-doped samples reveal better electrochemical performance than bare Na₂Li₂Ti₆O₁₄, especially for Na_1.9Nb_0.1Li₂Ti₆O₁₄, which can deliver the highest reversible charge capacity of 259.4 mAh g^–1 at 100 mA g^–1 among all samples. Even when cycled at higher rates, Na_1.9Nb_0.1Li₂Ti₆O₁₄ still can maintain excellent lithium storage capability with the reversible charge capacities of 242.9 mAh g^–1 at 700 mA g^–1, 216.4 mAh g^–1 at 900 mA g^–1, and 190.5 mAh g^–1 at 1100 mA g^–1. In addition, ex situ and in situ observations demonstrate that the zero-strain characteristic should also be responsible for the outstanding lithium storage capability of Na_1.9Nb_0.1Li₂Ti₆O₁₄. All of this evidence indicates that Na_1.9Nb_0.1Li₂Ti₆O₁₄ is a high-performance anode material for rechargeable lithium ion batteries