Enhancing glass anode performance for lithium‐ion batteries via crystallization

Abstract

We investigate the thermal and electrochemical properties of xFe2O3‐(100‐x) P2O5 glass (x = 20, 30, 40, and 50 mol%) and 50Fe2O3‐50P2O5 (50FeP) glass‐ceramics as anodes for lithium‐ion batteries (LiBs). The results show that both the glass transition temperature and the energy bandgap monotonically decrease with the increasing Fe2O3 while a critical Fe2O3 content of 30 mol% is found to give glass the highest thermal stability, the largest capacity at 1 Ag‐1, and the lowest charge‐transfer resistance before cycling. Moreover, Fe3(P2O7)2 crystals formed during heat treatment in 50FeP glass effectively enhances the electrochemical properties. The optimum heat treatment condition for 50FeP glass is found at 1033 K for 4 h, that is, 1033 K‐4 h sample enables a reversible capacity of 237 mA h g−1 at the end of 1000 cycles at 1 Ag‐1, which is more than 1.5 times higher than that of the 50FeP glass‐based anode. These findings suggest that the Fe2O3‐P2O5 glass‐ceramics hold significant potential for the effective development of new types of glass anodes for future advanced LiBs.

Iron‐phosphate glass‐ceramic anodes for lithium‐ion batteries

“…It is seen that 50Fe50P glass has a glass transition peak with T g = 773 K, followed by a sharp crystallization peak with the onset temperature of 980 K, which indicates a strong tendency of the glass to crystallization. 18 With increasing the upscaning temperature, two endothermic peaks related to melting of crystals appear at 1118 and 1250 K, respectively, suggesting the complex crystallization behavior of 50Fe50P. That is to say, the sharp crystallization peak in the DSC curve might be associated with the formation of at least two crystal phases.…”

“…That is to say, the sharp crystallization peak in the DSC curve might be associated with the formation of at least two crystal phases. 18,20,24 In this work, the heat-treatment temperature is chosen as 1118 K owing to the following two aspects. On one hand, the glass ceramics with a main crystal phase is expected to be obtained by melting some byproduct crystals in order to clearly study the effect of crystallization on the electrochemical performances.…”

“…The as-produced 50Fe50P glass is fully amorphous. 18 The identity of the crystalline phases is strongly affected by the heat-treating atmosphere. Under oxidizing condition, only one crystal phase of Fe The microstructural evolution of these two glass ceramics revealed a significant influence of the heat treatment atmosphere as is evident by the typical SEM images of A-0.5h and R-0.5h (Figures 2C,D).…”

“…We chose and prepared the 50Fe 2 O 3 -50P 2 O 5 (50Fe50P) glass as anode material for LiBs by using the meltquenching method. 18 50Fe50P glass was milled in an agate mortar for 0.5 h to prepare the powder. Figure 1 shows the particle size distribution of the glass powder, which are displayed as the volume of powder and the cumulative volume distribution.…”

“…In addition, the electrical conductivity of glasses can also be improved by the thermal-induced crystallization process. [18][19][20] A recent work of some of the present authors 18 demonstrated that the reversible capacity of 50Fe 2 O 3 -50P 2 O 5 glass anode for LiBs was enhanced by 1.5 times after 1000 cycles at the current density of 1 A g −1 due to the formation of Fe 3 (P 2 O 7 ) 2 crystals. This enhancement in capacity is mainly attributed to the crystallizationinduced increase of electronic conductivity.…”