Comparison of LiVPO₄F to Li₄Ti₅O₁₂ as Anode Materials for Lithium-Ion Batteries

Abstract

In this paper, we reported on a comparison of LiVPO4F to Li4Ti5O12 as anode materials for lithium-ion batteries. Combined with powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, galvanostatic discharge/charge tests and in situ X-ray diffraction technologies, we explore and compare the insertion/extraction mechanisms of LiVPO4F based on the V3+/V2+/V+ redox couples and Li4Ti5O12 based on the Ti4+/Ti3+ redox couple cycled in 1.0-3.0 V and 0.0-3.0 V. The electrochemical results indicate that both LiVPO4F and Li4Ti5O12 are solid electrolyte interphase free materials in 1.0-3.0 V. The insertion/extraction mechanisms of LiVPO4F and Li4Ti5O12 are similar with each other in 1.0-3.0 V as proved by in situ X-ray diffraction. It also demonstrates that both samples possess stable structure in 0.0-3.0 V. Additionally, the electrochemical performance tests of LiVPO4F and Li4Ti5O12 indicate that both samples cycled in 0.0-3.0 V exhibit much higher capacities than those cycled in 1.0-3.0 V but display worse cycle performance. The rate performance of Li4Ti5O12 far exceeds that of LiVPO4F in the same electrochemical potential window. In particular, the capacity retention of Li4Ti5O12 cycled in 1.0-3.0 V is as high as 98.2% after 20 cycles. By contrast, Li4Ti5O12 is expected to be a candidate anode material considering its high working potential, structural zero-strain property, and excellent cycle stability and rate performance.

A journey into the electrochemistry of vanadium compounds

“…There is a mention of LaVO 4 , examined together with other lanthanum transition-metal oxides as new negative anodic materials for alkaline batteries [316], but performance of V was inferior to that of other metals. Also from a comparison of LiVPO 4 F to Li 4 Ti 5 O 12 as anode materials [317], it resulted that electrochemical performances were better for the latter. Therefore, it seems that vanadium-based materials have promising characteristic for cathodic materials, but not for anodic ones.…”

Carbothermal synthesis of LiVPO4F and its structural change in a broad potential range observed by in-situ X-ray diffraction

“…All these evidences suggest that the electrochemical reaction between LiVPO 4 F and Li is quasi-reversible in 0.0-4.7 V and two structural transitions take place during the discharge process. Two structural transitions mean the appearance of two newly formed phases, which can be identified as Li 2 VPO 4 F and Li 3 VPO 4 F according to the FullProf calcualtion and previous reports [21,22]. According to the phase transition characteristics, this first transition is a biphasic reaction mechanism between LiVPO 4 F and Li 2 VPO 4 F and the following phase transition is a solid solution single-phase reaction between …”

“…Secondly, the resulting VPO 4 was mixed with the lithium fluoride (LiF, 98.5%) by planetary ballmilling and then calcined in Ar-filled tube furnace to form the final LiVPO 4 F sample. Detailed synthetic steps of LiVPO 4 F were also reported in our previous paper [1,21,22,25,26].…”

“…After that, most of studies about LiVPO 4 F were associated with the material preparation methods, but rarely related to its structural evolution during charge/discharge process, especially for the LiVPO 4 F-based battery in an over-discharge state. Most recently, some groups have reported the structural change of LiVPO 4 F in a narrow potential range [18][19][20][21][22][23]. However, the investigation of LiVPO 4 F at a deep over-discharge state is also very important to make it become a commercial cathode material.…”

In situ electrochemical creation of cobalt oxide nanosheets with favorable performance as a high tap density anode material for lithium-ion batteries

“…One significant advantage of conversion-type anodes is the versatile selection of available materials. By forming binary, ternary or even more complicated composite oxides, various materials with different capacities, rate performance and cycling stability can be developed [14][15][16][17]. For instance, hollow structured Li 3 VO 4 wrapped with graphene nanosheets as anode materials showed a reversible capacity of 223 mA h g À1 even at 20 C and no evident capacity fading after 500 cycles at 10C [18].…”