Leyden Energy (Leyden) is a Silicon Valley company that has developed a lithium ion battery that uses imide salts as electrolytes instead of the more commonly used PF6-based electrolytes.  Formerly known as Mobius Power, Leyden built it Li-imide battery platform on seed technology from a patent acquired by DuPont.

In addition to the DuPont patent, Leyden owns at least one U.S. patent and at least six pending applications.  U.S. Patent No. 8,221,915 is entitled “High performance lithium or lithium ion cell” (’915 Patent) and directed to lithium ion electrochemical cells comprising a case (100), a cover (200), which is the positive terminal, and an insulating ring (300) between the case and the cover.

A negative tab (400) connects the anode current collector to the cover, and a positive tab (500) connects the cathode current collector to the cover.  The cell also includes a positive terminal (550), a cathode (600), an anode (700), a separator (800), and an electrolyte solution inside the pores of the electrodes and separator.

The cathode (600) comprises an active material and a current collector made of aluminum foil with a protective, conductive coating, and the anode (700) comprises an active material and a copper foil current collector.

The crux of the ’915 Patent is the invention of a way to reduce the corrosion typically caused by lithium imide salts so their properties of superior thermal and hydrolytic stability can be harnessed to extend the life of the battery.  According to the ’915 Patent, Leyden’s unique combination of conductive protective coating and anti-corrosion additives achieves this goal:

The following examples describe and explain how synergy of conductive protective coating and corrosion inhibiting additives results in [the] possibility of using thermally stable salts described herein to achieve long battery cycle life with little degradation.

In particular, an electrolyte solution of Lithium bis(Trifluoromethanesulfonyl)Imide (LiTFSI) with the additive lithium bis(oxalato)borate significantly reduced corrosion over a one week testing period:

The corrosion of the protected samples did not occur with the whole duration of the test (one week).  This surprising finding shows the synergetic effect of using the protective coating and the corrosion inhibiting additive allows reduction or prevention of corrosion of the current collector corrosion.

This Greentech Media article notes Leyden’s claims that the lithim-imide electrolyte allows temperatures greater than convention lithium-ion batterys, longer cycle life, and higher charge density, and the follow-up piece reports on the company’s latest funding round.

Valence Technology is an Austin, Texas, company that develops and manufactures long-life lithium iron magnesium phosphate batteries. 

Valence recently won a victory in the European Patent Office (EPO) Opposition Board when the Board dismissed an appeal of a decision revoking a European patent held by rival Hydro-Quebec (HQ).

The EPO initially granted European Patent Number 0904607, entitled “Cathode materials for secondary (rechargeable) lithium batteries” (’607 Patent) to the University of Texas; the patent is now owned by HQ. 

Valence challenged the patent grant in an opposition proceeding filed in 2005.  The EPO Opposition Board revoked the grant in December 2008 because the patent lacked novelty (EPO_Revocation).  HQ appealed that decision. 

Last month the EPO Opposition Board dismissed HQ’s appeal, resulting in cancellation of the patent.

The ’607 Patent is a European relative of U.S. Patents Nos. 5,910,382, 6,514,640, 7,955,733, 7,960,058 and 7,964,308, entitled “Cathode materials for secondary (rechargeable) lithium batteries” (Cathode Materials Patents).

The Cathode Materials Patents relate to host materials for use as electrodes in lithium ion batteries.  In particular, the patents are directed to a synthesized cathode material containing a compound with an olivine structure comprising the general formula LiMPO₄ where M is iron, manganese, nickel or titanium.

According to the Cathode Materials Patents, these cathode materials provide a larger free volume for lithium ion motion that allows higher conductivity and therefore greater power densities.

Valence and HQ are not strangers to litigation involving the Cathode Materials Patents.  Read previous posts here and here about those cases, which the parties settled as part of a cross-licensing deal in October of last year.

David Gibbs is a contributor to Green Patent Blog.  David is currently in his third and final year at Thomas Jefferson School of Law in San Diego.  He received his undergraduate degree in Geology from the University of California, Berkeley.

Envia Systems is a Newark, California, company that develops high performance, low cost lithium-ion energy storage solutions. 

In a recent Press Release, Envia announced that they have achieved a world record 400 Watt-hour/kilogram (Wh/kg) energy density for rechargeable lithium-ion batteries.  This milestone comes after much development and testing:

Dr. Sujeet Kumar, Envia Systems co-founder said “Since the inception of Envia, our product team has worked tirelessly and logged over 25 million test channel hours to optimally develop each of the active components of the battery: Envia proprietary Si-C anode, HMCR [High Capacity Manganese Rich] cathode and EHV [Envia’s High Voltage] electrolyte.”

The anode, cathode and electrolyte materials appear to be described in several patent applications owned by Envia.

The patent applications describing Envia’s cathode are U.S. Patent Application Publication No’s:

2010/0086853 (’853 Application), entitled “Positive Electrode Materials for Lithium Ion Batteries Having a High Specific Discharge Capacity and Processes for the Synthesis of These Materials”;

2011/0076556 (’556 Application), entitled “Metal Oxide Coated Positive Electrode Materials for Lithium-Based Batteries”;

2011/0111298 (’298 Application), entitled “Coated Positive Electrode Materials for Lithium Ion Batteries”; and

2010/0151332 (’332 Application), entitled “Positive Electrode Materials for High Discharge Capacity Lithium Ion Batteries”

Figure 1 below is a depiction of  a battery taken from the ’853 Application.  The Figure depicts a battery (100), a negative electrode (102), a positive electrode (104), and a separator (103) between the positive electrode (104) and negative electrode (102).

Envia’s patent-pending process involves applying excess lithium, in the form of lithium manganese oxides, on the cathode to increase overall energy density. According to the ‘298 Application:

It is believed that appropriately formed lithium-rich lithium metal oxides have a composite crystal structure in which the excess lithium supports the formation of an alternative crystalline phase.  For example, in some embodiments of lithium rich materials, a Li2MnO3 material may be structurally integrated with either a layered LiMnO2 component or similar composite compositions with the manganese cations substituted with other transition metal cations with appropriate oxidation states.

At least one of Envia’s patent applications describes an anode: Patent Application Publication No. 2011/0111294, entitled “High Capacity Anode Materials for Lithium Ion Batteries” (’294 Application).

According to the ’294 Application:

Desirable high capacity negative electrode active materials can be based on nanostructured silicon materials and/or composites with nanostuctured carbon materials.  In particular, nanostructure silicon can comprise elemental silicon nanoparticles and/or porous elemental silicon, as well as corresponding silicon alloys and composites thereof … carbon coatings can be applied over the silicon-based materials to improve electrical conductivity, and the carbon coatings seem to also stabilize the silicon based material with respect to improving cycling and decreasing irreversible capacity loss.

At least two patent applications describe Envia’s electrolyte:

2011/0052981 (’981 Application), entitled “Layer-Layer Lithium Rich Complex Metal Oxides with High Specific Capacity and Excellent Cycling”; and

2011/0017528  (’528 Application), entitled “Lithium Ion Batteries with Long Cycling Performance”

The common theme throughout all the patent applications is the effect small changes in battery chemistry and materials have on performance.  According to the ‘556 Application:

It has been found that relatively small amounts of metal oxide coating on a lithium rich metal oxide active material can provide desirable improvements in lithium-based battery performance with respect to both specific discharge capacity and cycling.

Envia’s batteries have environmental benefits in addition to their ability to store a record amount of energy.  According to the ‘853 Application:

These compositions [in the batteries] use low amounts of elements that are less desirable from an environmental perspective, and can be produced from starting materials that have reasonable cost for commercial scale production.

Envia’s new battery technology was tested by the Electrochemical Power Systems Department at the Naval Surface Warfare Center in Crane, Indiana.  The test results confirmed Envia’s claims regarding its batteries demonstrating an energy density between 378-418 Wh/kg. 

Envia’s Systems Chairman and CEO, Atul Kapadia noted the potential implications for electric vehicles:

In an industry where energy density tends to increase five percent a year, our achievement of more than doubling state-of-art energy density and lowering cost by half is a giant step towards realizing Envia’s mission of mass market affordability of a 300-mile electric vehicle.

In fact, drivers may see Envia batteries in future General Motors electric vehicles.  General Motors Ventures LLC invested $17 million in Envia in a 2011 equity investment round and, in a separate agreement, secured the right to use Envia’s cathod material in GM EVs.

David Gibbs is a contributor to Green Patent Blog.  David is currently in his third and final year at Thomas Jefferson School of Law in San Diego.  He received his undergraduate degree in Geology from the University of California, Berkeley.