Solid state electrochemical cell including lithium iodide as an electrolyte additive

• US 5,458,995 A
• Filed: 04/20/1995
• Issued: 10/17/1995
• Est. Priority Date: 08/12/1994
• Status: Expired due to Fees

• Current Assignee: United States Army (U.S. Department Of Defense)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Behl, Wishvender K., Plichta, Edward J.
• Primary Examiner(s): Kalafut, Stephen
• Assistant Examiner(s): LILLEY, RICHARD
• Application Number:
  US08/425,568
• Time in Patent Office: 180 Days
• Field of Search: 429/191, 429/193, 429/218
• US Class Current: 429/322
• CPC Class Codes: H01M 10/39 working at high temperature
• CPC Class Codes: H01M 6/185 with oxides, hydroxides or oxysalts as solid electrolytes
• CPC Class Codes: H01M 6/36 containing electrolyte and made operational by physical means, e.g. thermal cells
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An improved solid state electrochemical cell is provided including a lith ion conducting solid electrolyte. The lithium ion conducting solid electrolyte is a solid solution of lithium germanium oxide and lithium vanadium oxide that includes lithium iodide as an additive. The improved cell can be used as a high temperature high rate rechargeable cell or as a high temperature thermal cell.

Claims

1. An improved solid state electrochemical cell including an alloy of lithium as an anode, a solid solution of lithium germanium oxide and lithium vanadium oxide as a lithium ion conducting solid electrolyte and wherein said solid electrolyte also includes an additive that improves the conductivity of the electrolyte, and a lithium intercalating compound as a cathode.

2. An improved solid state electrochemical cell according to claim 1 wherein the lithium alloy is selected from the group consisting of LiAl, LiSi, LiB, wherein the lithium ion conducting solid electrolyte is a solid solution of lithium germanium oxide and lithium vanadium oxide including LiI as an additive that improves the conductivity of the electrolyte, and wherein the cathodic intercalating compound is a compound selected from the group consisting of transition metal halides, transition metal chalcogenides, transition metal selenides, transition metal tellurides and transition metal oxides.

3. An improved solid state electrochemical cell according to claim 2 where the anode is a lithium silicon alloy of about 48 weight percent lithium, wherein the solid electrolyte is represented by the general formula Li_3+x Ge_x V_1-x O₄ where x has a value of from 0 to 1 and wherein the solid electrolyte includes 0 to 100 percent of the weight of the solid electrolyte of LiI as an additive that improves the conductivity of the electrolyte, and wherein the cathodic intercalating compound is selected from the group consisting of TiS₂, FeS₂, CoS₂, NiS₂, LiCoO₂, LiNiO₂, LiMnO₂, V₆ O₁₃, V₂ O₅, MoS₂, MoS₃, NbSe₃, VSe₂, AgF, CuF₂, CuCl₂, CuCl, and NiF₂.

4. An improved solid state electrochemical cell comprising lithium-silicon as the anode, a mixture of Li₃.6 Ge₀.6 V₀.4 O₄ and LiI as the electrolyte, and TiS₂ as the cathode.

5. A solid state electrolyte for use in a lithium electrochemical cell, said solid state electrolyte including a solid solution of lithium germanium oxide and lithium vanadium oxide, the solid state electrolyte also including an additive that is chemically stable in the presence of lithium and lithium containing anode materials.

6. A solid state electrolyte according to claim 5 wherein the additive is LiI.

7. A solid state electrolyte according to claim 6 wherein the solid electrolyte is represented by the general formula Li_3+x Ge_x V_1-x O₄ and, wherein where x varies from 0 to 1.