Carbon‐Coated Li₃Nd₃W₂O₁₂: A High Power and Low‐Voltage Insertion Anode with Exceptional Cycleability for Li‐Ion Batteries

Abstract

material is highly warranted. Several prospective materials have been proposed as anode insertion hosts to reversibly accommodate Li-ions; for example, anatase TiO 2 (≈1.7 V vs. Li with theoretical capacity of 335 mAh g −1 ) [ 6 ] and monoclinic TiO 2 -B (≈1.55 V vs. Li with theoretical capacity of 335 mAh g −1 ), [ 7,8 ] Li 4 Ti 5 O 12 (≈1.5 V vs. Li with theoretical capacity of 175 mAh g −1 ), [ 9,10 ] LiCrTiO 4 (≈1.5 V vs. Li with theoretical capacity of 157 mAh g −1 ), [ 11,12 ] TiP 2 O 7 (≈2.6 V vs. Li with theoretical capacity of 121 mAh g −1 ), [ 13,14 ] LiTi 2 (PO 4 ) 3 (≈2.6 V vs. Li with theoretical capacity of 138 mAh g −1 ), [ 15,16 ] Li 3 V 2 (PO 4 ) 3 (≈1.7 V vs. Li with theoretical capacity of 132 mAh g −1 ), [ 17 ] Nb 2 O 5 (≈1.7 V vs. Li with theoretical capacity of 403 mAh g −1 ) [ 18 ] and TiNb 2 O 7 (≈1.6 V vs. Li with theoretical capacity of 388 mAh g −1 ) [ 19 ] ( Figure 1 ). The mentioned insertion-host materials showed much higher insertion potential (>1.5 V vs. Li) and very less practical capacity (<300 mAh g −1 ) than graphitic anodes (≈0.1 V vs. Li), which results in a drastic reduction of overall energy density when coupled with a high performance cathode. On the other hand, displacement and alloy-based anodes exhibit a higher capacity than insertion electrodes, but they experience huge irreversible capacity loss in the fi rst cycle, large volume changes, and poor long-term cycleability, which renders them as "show case" anodes. [ 5,20 ] This situation clearly shows the importance of the development of low-voltage insertion-type anodes to realize the construction of high energy density Li-ion power packs to fulfi l the requirements for HEV and EV applications. [ 4 ] Recently, Goodenough and co-workers [ 21 ] reported the possibility of using a garnet framework Li 3 Nd 3 W 2 O 12 as a low-voltage (≈0.3 V vs. Li) insertion anode for LIB applications. Generally, such garnet materials are considered as fast Li-ion conductors with ionic conductivities of >10 −4 S cm −1 in ambient conditions. [ 22 ] The crystal structure of the lithium garnet framework can be described as Li 3 A 3 B 2 O 12 in which Li occupies square anti-prismatic, octahedral and tetrahedral sites in 3:2:3 ratio. [ 23 ] The tetrahedral Li-sites are bridged by empty octahedra sharing opposite faces with two tetrahedral sites; every face of a Lisite is bridged to neighboring Li-sites by the means of octahedral sites to provide a 3D interstitial space. This interstitial space can accommodate 9 moles of Li, but a practical limit of 7 moles of Li has been set. In the present case, the W 6+/4+The synthesis of carbon-coated Li 3

TiO2 polymorphs in ‘rocking-chair’ Li-ion batteries

“…Pre-treating the electrode is one of the efficient method for ICL suppression, and this process has been successfully adopted for the fabrication of Li-ion capacitors using pre-lithiated graphitic anodes [22] and insertion electrodes for LIB applications [9,53]. Of late, Brutti et al [54] introduced the concept of incorporating a small amount of nano-Li into the anatase phase to suppress the ICL observed in the first cycle.…”

“…Their potential use is hindered mainly due to unavoidable electrolyte decomposition and subsequent solid electrolyte interface (SEI) formation over the carbonaceous anodes in the first cycle, occurrence of Li-plating at high current rates, and a poor low-temperature performance. Thus, several transition metal oxide based insertion hosts, including LiCrTiO 4 , TiP 2 O 7 , LiTi 2 (PO 4 ) 3 , TiNb 2 O 7 , Nb 2 O 5 , Li 4 Ti 5 O 12 , and TiO 2 , have been proposed as possible alternatives to the graphitic anodes [8][9][10][11][12][13][14][15]. While these insertion anodes have no SEI formation and an excellent high rate performance, but higher operating potential (>1.5 V vs. Li) and less reversible/theoretical capacity than graphitic anode remains an issue.…”

Research Progress on Negative Electrodes for Practical Li‐Ion Batteries: Beyond Carbonaceous Anodes

“…Li) insertion anode with high power capability. Satish et al [ 294 ] succeeded at making a uniform carbon coating over Li 3 Nd 3 W 2 O 12 particulates to realize applications as an anode in LIBs. The structural properties of such a lithium garnet framework can be described as Li 3 ratio.…”

TiNb2O7 nanoparticles assembled into hierarchical microspheres as high-rate capability and long-cycle-life anode materials for lithium ion batteries

“…23,24 Therefore, it shows the great importance of the development of materials with large Li ion storage capacities at high charge-discharge rates for the use as anodes in the LIBs of high power systems. 23,24 Therefore, it shows the great importance of the development of materials with large Li ion storage capacities at high charge-discharge rates for the use as anodes in the LIBs of high power systems.…”