Focus: Titanate Cathode Materials for Li-ion Batteries

Lithium metal titanate and zironate compounds phases are currently experiencing significant interest as potential new cathode active materials for next generation Li-ion batteries. Jerry Barker (and co-workers) is the named inventor on the issued US patents covering the use of LiMTiO4 and LiMZrO4 (where M= +3 oxidation state transition metal, US#6,103,419); and Li2MTiO4 and Li2MZrO4 (where M = +2 oxidation state transition metal, US#6,720,113) materials; in these energy storage applications.

Further information about these materials and their performance in Li-ion cells may be found in the issued US patents. Links to these patents may be found here:

J.Barker et al. US#6103419; LiMTiO4 and LiMZrO4 Cathode Materials (M = V, Cr, Fe, Mn etc.)

J.Barker et al. US#6720113; Li2MTiO4 and Li2MZrO4 Cathode Materials (M= Fe, Mn, Ni, Co etc.)

The US patent covering the novel synthesis method for some of these materials may be found here:

J.Barker et al. US#6706445; Titanate and Zirconate Synthesis Method

Jerry

Focus: Hybrid-ion Batteries

Hybrid-ion cells are a new and exciting concept in energy storage technology.

Background: During charge and discharge of conventional Li-ion cells, lithium ions are shuttled back-and-forth between the two insertion-based electrode materials. These processes are well understood and characterized.

In hybrid-ion cells, a non-lithium containing cathode material is coupled with a suitable lithium-based anode material such as graphite, hard carbon or lithium titanate, Li4/3Ti5/3O4. This simple but novel approach greatly increases the number of commercially useful cathode materials. By comparison with lithium, only a limited number of sodium insertion materials have been properly characterized for use in energy storage devices.

The electrochemical system is completed by the use of a conventional lithium-based non-aqueous electrolyte. During the initial charge process, Na ions are extracted from the cathode while concurrent lithium ion insertion occurs at the negative electrode. During subsequent cell discharge, lithium ions are extracted from the negative electrode while a mixed sodium/lithium insertion reaction occurs at the positive electrode. These reactions are fully reversible and in prototype cells very long lifetimes have been demonstrated. All the electroactive lithium ions in the electrochemical system originate from the electrolyte phase.

More details on this novel energy storage concept may be found below.

Hybrid-ion: A Lithium-ion Cell based on a Sodium Insertion Material.

J. Barker et al., ESL 9, A190, (2006)

Li4/3Ti5/3O4//Na3V2(PO4)2F3: An example of a Hydrid-ion Cell based on a non-graphitic anode

J.Barker et al., JES 154, A882, (2007)

Jerry

Focus: Sodium-ion Batteries

In my opinion, sodium-ion batteries represent an important energy storage alternative to conventional lithium-ion technology. Based on initial data these batteries should offer similar electrochemical characteristics to their lithium counterparts. In addition, they may provide some significant performance advantages such as: lower material costs and improved safety performance. These properties will be particularly important in future large format uses such as automotive (EV/PHEV) and stationary applications.

Based on these facts it is somewhat surprising that so little research effort has been dedicated to the commercial development of these energy storage systems. Part of the problem is the identification of suitable Na insertion anode materials. Unfortunately, graphite (the preferred negative electrode materials in Li-ion cells) does not allow significant Na ion uptake. Recent work, however has demonstrated significant amounts of sodium may be reversible cycled in disordered, hard carbon hosts. This has allowed the creation of some novel sodium-ion chemistries.

For instance, we recently reported the preliminary performance characteristics of the Hard Carbon//NaVPO4F cell. The abstract to the work may be found here:

Barker et al; A Sodium-ion Cell based on the Fluorophosphate Compound NaVPO4F

Further details on this, and other polyanion based sodium-ion cells may be found here:

Barker et al; US Patent #6872492

Jerry

LiMnPO4 News: HPL acquired by the Dow Chemical Company

Related to the discussions regarding the LiMnPO4 active material:

Green Car Congress (Nov. 12, 2009) reports that the Dow Chemical Company has announced the transfer to Dow of collective assets from High Power Lithium, HPL. HPL was spun out from Professor Graetzel’s laboratory at the EPFL (Ecole Polytechnique Federale de Lausanne, Switzerland) in 2003 and is focused on the development of nano-structured metal oxide energy storage materials and novel electrolytes for use in next generation lithium ion batteries.

HPL brings synthesis and development of novel nano-materials, the ability to process and optimize nano-materials for use in battery electrodes and cells, comprehensive physical and electrochemical characterization facilities and screening and development of novel electrolytes and systems.

More information may be found here:

Dow Chemical Company Press Release:

http://news.dow.com/dow_news/corporate/2009/20091112c.htm

High Power Lithium website:

http://www.highpowerlithium.com/

Jerry