Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From sulfur-containing reactant
Reexamination Certificate
2001-04-17
2004-04-27
Kalafut, Stephen J. (Department: 1745)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From sulfur-containing reactant
C429S314000, C429S316000, C429S317000, C526S248000, C528S394000, C528S395000, C528S397000, C528S422000
Reexamination Certificate
active
06727343
ABSTRACT:
BACKGROUND OF THE INVENTION
Improvements in solid state lithium batteries have increasingly focused on the solid polymer electrolyte, because this component continues to be the major obstacle in fashioning solid state batteries that can displace their liquid electrolyte counterpart Perfection of a successful solid polymer electrolyte is the linchpin in obtaining a competitive solid state lithium battery.
One of the primary objectives of recent SPE research has been to improve the ionic conductivity of these materials. Historically, this research has dealt with a number of variations of the early poly(ethyleneoxide) [PEO] work of Armand (Armand, M. B.; Chabango, J. M. and Duclot, M., 2nd Int. Conf on Solid Electrolytes, Extended Abstracts 20-22, St Andrews, (1978)) in an attempt to find a polymer that could support good ambient temperature ionic conductivity. Early work involved making PEO more amorphous by including flexible groups in the polymer. Two representative examples in this approach include poly[bis-(methoxyethoxyethoxide)]phosphazene MEEP and polyethoxy(ethoxy-ethoxy-vinyl)ether PEEVE (Blonsky; P. M., Shriver; D. R.; Austin; P. and Allcock; J.,
J. Am. Chem. Soc
., 106, 6854, (1984)). Inclusion of siloxane links in a PEO copolymer has been another general approach to enhance the amorphous character of PEO. Unfortunately, both approaches exhibit short comings including poor mechanical properties which limit their appeal. Recently, the combination of thermoplastic polymers with liquid electrolytes (i.e. ethylene carbonate, propylene carbonate) resulted in a “gelled” electrolyte and represented a clever attempt to tap the better properties of solvents in a solid electrolyte (Abraham, K. and Alamgir, G.
J. Power Sources
, 43-44, 195-208, (1993)). Although the ionic conductivities of the gelled polymer electrolytes have been among the highest measured in a room temperature polymer electrolyte, problems persist, because of the dubious mechanical and chemical properties of these materials (Dautenzenberg, G.; et al,
Chem. Mater
., 6, 538-42, (1994)).
All of these approaches have focused on using ether oxygens in the “solvent” (either a liquid or a polymer) to solubilize and coordinate lithium salt cations that carry the ionic charge through the electrolyte. In the case of the liquid electrolyte, the solvent is carried along with the cation through the bulk of the electrolyte. In the case of the true “solventless” solid polymer electrolyte, the polymer is stationary and the cations are moved along the chain from one ether oxygen (active site) to the next by the segmental motion of the polymer. This is one reason why amorphous polymers are superior to crystalline polymers in promoting ionic conduction. The amorphous polymer model of cations moving along the chain is an oversimplification. Gray gives a more graphic description of the process that takes into account ion-ion association, and inter and intrachain ion hopping (Gray, F. M., “Polymer Electrolytes”, RSC Monograph, The Royal Society of Chemistry, Cambridge, UK, (1997)). However, as Gray points out, the exact mechanism of ion conduction in a solventless polymer is as yet unknown.
In early attempts to improve on the properties of PEO, amorphous analogs such as poly(ethyleneimine)[—(CH
2
CH
2
NH)
x
—, PEI] and polyalkylene sulfides [—([CH
2
CH
2
]
n
S)
x
—, PAS] were prepared and combined with various metal salts to form SPEs. These materials were intended to be the polymeric analogs to amino and thia organic solvents such as acetonitrile and dimethylsulfoxide that have been shown to form useful aprotic electrolytes for lithium batteries. It was expected that the PEI and PAS polymers would be more amorphous and would lead to more conductive SPEs. Unfortunately, this was not the case, and both polymers were found to have properties that were, at best, equivalent to PEO. The instant invention is designed to overcome the shortcomings of the solid polymer electrolyte materials developed to date.
OBJECTS OF THE INVENTION
It is an object of the invention to provide the novel compounds of formulas I and II and a process of preparing the same.
It is another object of the invention to provide a novel process for the preparation of solid polymer electrolytes using polymer compounds of the formula I and various lithium salts.
It is still another object of the invention to describe novel uses of these new compounds.
These and other objects and advantages of the invention will become obvious from the following detailed description.
SUMMARY OF THE INVENTION
The present invention constitutes a new family of polymers that can be used for a variety of applications, including preparation of solid polymer electrolytes for batteries. The combination of inorganic elements with organic carbon segments to form a thermodynamically stable material is novel and heretofore unprecedented. The novelty of the proposed material lies in its unique combination of soft acid, strong acid elements linked together with organic spacers to provide a new material with an amorphous character and physical and chemical properties distinct from its counterparts polyethyleneoxide or polyethyleneimine.
One general embodiment of the present invention can be summarized by the general structure shown below.
where R is an element chosen from the group P or B or Al and M is an element chosen from the group Si or Ti and Q is an element chosen from the group S, O or N. The phosphorus can be present in either the
+
3 or
+
5 oxidation state especially
These elements are connected using hydrocarbon or fluorocarbon spacers, an example of which is the —CH
2
—CH
2
-ethylene linkage, and the entire molecule forms a heteroatomic polymer. The spacers of this polymer also include crosslinkage groups. The polymer can be of varying molecular weight ranging from 400 to 1,000,000 MW. The array of ethylene spacer and element groups , i.e.
can vary from an even distribution of each ethylene spacer and element group to an uneven distribution in ratios of 2 Q1 groups to one Q2 group to 5 Q1 groups to 1 Q2 group. Besides using ethylene carbon spacers in this polymer, the elements can also be connected using propylene and butylenes spacers. In addition, combinations of ethylene and propylene or butylene spacers can be used to connect the heteroatomic elements in the polymer. The spacers can also have alternating odd and even numbers of —CH
2
— or —CF
2
-links. This will ensure greater amorphous character in the polymer. Fluorocarbon analogs to these hydrocarbon groups can also be employed together with hydrocarbon groups or in direct replacement for hydrocarbon groups. In addition to using the select elements directly, in certain circumstances some of these select elements can contain organic substitutents that modify the characteristics of the polymer. For example: in the case of P or N, an organic substitutent can be added prior to polymerizing the monomers used to prepare the polymer
In this instance, the R3 group can be an alkyl or aryl group, e.g. methyl, nitrophenyl or aminophenyl group. The same circumstances apply to the triavalent element phosphorus. In this latter instance, the P atom could be connected to ethylene groups via an oxygen atom, or could be bonded directly to the carbon of the ethylene group or similar alkyl or fluoroalkyl substituent or spacer. Here again the species with phosphorus in the +5
oxidation state are also viable.
In another embodiment of the basic concept, of the essentials of the invention could be combined according to the following general structure:
where R1 is an element chosen from the group N, B or S and R2 is an element chosen from the group: O or P. In addition, R1 can be O while R2 is P in this compound. In all cases, phosphorus can be in the
+
3 or
+
5 oxidation state. Once again, these elements are connected using ethylene or propylene spacers and the entire molecule forms a heteroatomic polymer. The polymer can be of varying molecular weight ranging from 400 t
Dixon Brian Gilbert
Morris Robert Scott
Gaudet Stephen J.
Kalafut Stephen J.
Perkins Smith & Cohen LLP
Phoenix Innovation, Inc.
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