A low external temperature method for synthesis of active electrode materials for Li batteries – Part B: Synthesis of lithium iron oxides Li x Fe y O z

Abstract

Anode materials for lithium-ion batteries based on iron oxides were synthesized using two different methods: a Low External Temperature Method (LETM) and a conventional Solid State Reaction Method (SSRM). Both methods lead to the formation of final products representing a mixture of two phases: approximately 75% LiFeO 2 and 25% Li )x Fe 5 O 8 (0 < x £ 0.1). When compared with the ordinary solid state synthesis, LETM creates conditions for carrying out the synthesis at a lower external calcination temperature (200°C) over a shorter period. The properties of the Li x Fe y O z obtained by the LETM were compared with those of the same compound obtained by SSR at 700°C. Higher initial discharge capacity was displayed by the sample synthesized by the SSR method, while a superior cycling stability was shown by the sample synthesized by the LETM. The latter shows approximately double capacity at the 30th cycle as compared with the sample synthesized by SSRM.

Synthesis of carbon coated nanocrystalline porous α-LiFeO2 composite and its application as anode for the lithium ion battery

“…During the first cycle the lithium insertion proceeds through different steps, and the first discharge curves can be divided into four regions, marked as I, II, III, and IV. From regions I to III, the theoretical capacity of ␣-LiFeO 2 could be calculated on the basis of the following electrochemical reaction [19]:…”

“…The main reason is that their nanocrystalline porous architectures present large surface areas and thin walls, which are beneficial to the transportation of lithium ions in the active materials and to decreased polarization [10][11][12][13][14][15][16][17]. However, among all the transition metal oxides, iron oxide has attracted much attention because it is non-toxic and contains the most abundant and low cost metal available in the world [18][19][20][21][22]. It is well known that LiFeO 2 has different forms, i.e., ␣, ␤, and ␥-conjugated forms, as determined by the method and conditions of synthesis, and the various forms were also studied as potential alternatives to Li-Co-O positive electrodes [23][24][25][26][27][28].…”

“…In terms of use as a cathode material, many problems still remain, such as a low operating voltage, poor electrochemical activity, especially for the cubic ␣ and ␥-forms, and low capacity retention during the cycling tests. Despite its poor electrochemical characteristics as a cathode in lithium-ion bat- teries, LiFeO 2 has been investigated as an anode material within the voltage range of 0.01-2.5 V vs. Li/Li + [19]. Yet until now, there have been very few reports on LiFeO 2 materials used as anode for the Li-ion batteries.…”

“…Yet until now, there have been very few reports on LiFeO 2 materials used as anode for the Li-ion batteries. Unfortunately, none of the reported results shows promising anode properties in rechargeable lithium cells [19,29]. So, it is very interesting to explore the synthesis of ␣-LiFeO 2 materials (theoretical specific capacity 848 mAh g −1 ) and their application as anode for the Li-ion battery.…”

Facile synthesis of iron-based compounds as high performance anode materials for Li-ion batteries

“…22 Lithium ferrite also can be used as anode materials, however, there are few reports on lithium ferrite used as anode materials and almost all the reported results showed poor electrochemical performances. [23][24][25] Therefore, it is a challenge to develop a simple synthetic strategy for high performance lithium ferrite anode materials for LIBs.…”