Non-carbon Anode Materials for Lithium Batteries

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CONTENTSI

Anode Materials for Lithium ion BatteriesI Non-carbon Anode materials

II1.Insertion (Intercalation/de-intercalation)-type materials.

2.Alloy/de-alloy materials.

3.Conversion materials.

Summary

Anode Materials for Lithium ion Batteries

Current lithium ion technology is based on a layered LiCoO2 cathode and graphite anode

Anode Material for Lithium ion Batteries

Find alternative material for lithium ion batteries

Graphite Exfoliation

Reduce cycle life of battery

Low capacity (372 mah/g)

Can accommodate only one Li-ion with six Carbon

Easy exfoliation

Anode material for lithium ion batteries

Schematic illustration of active anode materials for the next generation of lithium batteries. Potential vs. Li/Li+ and the corresponding capacity density are shown.

S. Goriparti et al. / Journal of Power Sources 257 (2014) 421-443

Non-carbon Anode Materials

1) Intercalation/de-intercalation materials, such as TiO2, Li4Ti5O12, etc;

2) Alloy/de-alloy materials such as Si, Ge, Sn, Al, Bi, SnO2, etc;

3) Conversion materials like transition metal oxides (MnxOy, NiO, FexOy, CuO, Cu2O, MoO2 etc.), metal sulphides, metal phosphides and metal nitrides (MxXy; here X = S, P, N).

Insertion-type Materials for Lithium ion Battery

Titanium Based OxidesLi4Ti5O12 is considered the most appropriate titanium based oxide material for lithium storage purposes because1. It exhibits excellent Li-ion reversibility at the high operating potential

of 1.55 V vs. Li/Li+. 2. Lithium insertion/extraction in LTO occurs by the lithiation of spinel

Li4Ti5O12 yielding rock salt type Li7Ti5O12. 3. During the insertion process, the spinel symmetry and its structure

remain almost unaltered.

A.S. Prakash, P. Manikandan, K. Ramesha, M. Sathiya, J.M. Tarascon, A.K. Shukla, Chem. Mater. 22 (2010) 2857-2863.

The cation distribution in Li4Ti5O12 and Li7Ti5O12 phases during electrochemical charge/discharge processes could be written as follows:

Limitation:Its poor electronic conductivity (10-13 Scm-1) limits its full capacity at high charge and discharge.

Growing of LTO nanowires on titanium foil and an improvement in the conductivity of LTO nanowires by introducing Ti3+ ions through hydrogenation

L. Shen, E. Uchaker, X. Zhang, G. Cao, Adv. Mater. 24 (2012) 6502-6506

These nanowires containing Ti foil were directly used as electrodes without any conductive additives and binders, and they exhibited brilliant rate performance by reaching a capacity value close to the theoretical one, i.e. 173 mAhg-1 at 0.2C rate with good cycle life. Moreover, this value became 121 mAh g-1 at 30C.

Insertion-type Materials for Lithium ion Battery

Alloy/De-Alloy Materials

Which can react with lithium to form alloys

The working voltage of Sn and Sn alloys at 0.6V vs lithium is 0.2V higher than that of Si and Si alloys

Tin oxide (SnO2):

Reversible Sn-lithium alloying/ dealloying reaction:SnO2 + 4Li ↔ Sn + 2Li2O, Sn + 4.4Li+ ↔ Li4.4SnThis overall electrochemical process involves 8.4Li for one SnO2 formula unit.

Tin Based Anode Materials

various morphological structures of SnO2 have been widely investigated such as nanowires, nanotubes, nanorod, nanoboxes and nanosheets

Short size SnO2 nanotubes showed better electrochemical behavior in terms of capacity and cycling life. The measured discharge capacity was 468 mAh g-1 after 30 cycles

J. Ye, H. Zhang, R. Yang, X. Li, L. Qi, Small 6 (2010) 296-306

Tin Based Anode Materials

Conversion MaterialsIn this section we will provide an overview on the transition metal compounds such as oxides, phosphides, sulphides and nitrides (MxNy; M = Fe, Co, Cu, Mn, Ni and N = O, P, S and N) when utilized as anodes in LIBs. Anodes based on these compounds exhibit high reversible capacities (500-1000 mAhg-1 ) owing to the participation of a high number of electrons in the conversion reactions. The electrochemical conversions reactions can be described as follows:

MxNy + zLi+ + ze- ↔ LizNy + xM

(Here M = Fe, Co, Cu, Mn, Ni & N = O, P, S and N)

Iron oxideIron based oxides have been extensively used for rechargeable lithium batteries for the following Advantages:

Low cost Non toxicity High Natural Abundance

Limitation: 1.Poor cycle performance.2.Low diffusion of Li-ions.3. High Volume expansion during charging and discharging.

Very recently, nanoparticulate Fe2O3 tubes have been obtained from microporous organic nanotubes (MONT) used as template. The prepared porous Fe2O3 nanotubes exhibited excellent electrochemical performances with large capacities such as 918 and 882 mAhg-1 at current densities of 500 and 1000 mAg-1 , respectively. These results indicate that low cost iron based oxides with highly conductive carbon composites can be a valid alternative to graphite anodes.

N. Kang, J.H. Park, J. Choi, J. Jin, J. Chun, I.G. Jung, J. Jeong, J.-G. Park, S.M. Lee, H.J. Kim, S.U. Son, Angew. Chem. Int. Ed. 51 (2012) 6626-6630.

Iron oxide

Metal phosphides (MPx)MPx divided into two groups. The first one involves the lithium insertion/extraction without breaking the metalephosphorous bond, known as insertion/de-insertion mechanism:

MxPy + zLi+ ze- ↔ LizMx-zPy

The second group involves a conversion reaction mechanism. :

MxPy + zLi+ ze ↔ LizPy + xM

Copper, cobalt, iron, nickel and tin based phosphides are usually considered to belong to the second group, i.e. conversion mechanism.

Summary

1. The intercalation/de-intercalation group, which includes titanium oxides materials, was illustrated. The storage capacity, that occurs through an intercalation path, is closely associated to the surface area, morphology, crystallinity and its orientation.

2. Alloying materials such as SnO2 was described. These materials can provide larger capacities and high energy density compared to the previous group, by reacting with lithium in an alloy/de-alloy electrochemical mechanism

3. Materials reacting with lithium in a conversion reaction fashion were described. In particular, metal oxides/ phosphides were considered. However, these materials are still far away from the large commercial lithium battery market, due to poor capacity retention and large potential hysteresis

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