JP2019207884A - Primary battery or secondary battery electrode in which local battery reaction is controlled, and primary battery or secondary battery using electrode - Google Patents

Abstract

To provide a method for suppressing a memory effect, improving the durability and improving the capacity in a battery using a secondary battery electrode.SOLUTION: In a method for suppressing deterioration due to local battery reaction in a battery using an electrode for a primary battery or a secondary battery including an electrode active material layer having an electrode current collector and an electrode active material, the electrode current collector has, on the surface, a layer made of at least one selected from the group consisting of a substance that controls local battery reaction that occurs between an electrode battery assembly and the electrode active material, which is a substance having an electrode potential higher than -0.75 V compared to the electrode active material and a substance electrochemically inert to an electrolyte, or a layer including at least one selected from the group consisting of a substance having an electrode potential higher than -0.75 V compared to the electrode active material and a substance that is electrochemically inert to the electrolyte.SELECTED DRAWING: None

Description

  The present invention relates to an electrode for a primary battery or a secondary battery in which a local battery reaction is controlled, and a primary battery or a secondary battery using the electrode.

  Alkaline secondary batteries such as nickel metal hydride batteries and nickel cadmium batteries have features such as high capacity, excellent discharge characteristics at high power and large current, and high safety. Widely used in various fields, including cars. In particular, the energy density of a nickel metal hydride battery is higher than that of a nickel cadmium battery, a lead storage battery, or the like, and has a low environmental load and high safety.

For example, taking a nickel metal hydride battery as an example, the positive electrode is nickel hydroxide (Ni (OH) ₂ ), the negative electrode is a hydrogen storage alloy (MH: M represents an alloy), and the electrolyte is a potassium hydroxide aqueous solution (KOH (aq )) Etc., the reaction formula at the time of charging / discharging is expressed as follows.

Positive electrode: NiOOH + H ₂ O + e ⁻ ⇔ Ni (OH) ₂ + OH ⁻
Negative electrode: MH + OH ⁻ ⇔ M + H ₂ O + e ⁻
However, if the alkaline secondary battery is fully charged before it is fully discharged, then when it is discharged, a phenomenon in which the electromotive force is remarkably reduced before it is fully discharged, the so-called memory effect occurs, As a result, the capacity seems to have decreased.

  Conventionally, when the memory effect occurs, a method of eliminating the memory effect by forcibly deeply discharging and then charging again has been widely adopted.

  However, this method is not a drastic solution because it does not suppress the occurrence of the memory effect. In addition, it takes time and electricity to discharge deeply, and it is difficult to completely recover the capacity, and the capacity and durability are not sufficient. Moreover, such specialized operations have been one factor that hinders the spread of batteries. Such harmful effects are considered to be seen not only in secondary batteries but also in primary batteries.

Various studies have been conducted on the memory effect so far. According to Sato et al., The nickel hydrogen battery is usually charged during charging, and the positive electrode Ni (OH) ₂ is changed to β-NiOOH. However, it is said that γ-NiOOH is generated by repeating shallow charge / discharge (Non-patent Document 1). On the other hand, γ-NiOOH is generated by overcharge and is described in the battery column as being more oxidized than β-NiOOH (Battery Handbook 3rd edition issued on February 20, 2001, Maruzen Co., Ltd.) ).

Yuichi Sato et al., J. Power Sources 93 (2001) 20-24.

  An object of the present invention is to provide an electrode for a primary battery or a secondary battery that can suppress a memory effect, improve durability, and improve capacity.

  Conventionally, as described above, it was thought that γ-NiOOH was generated from β-NiOOH by repeating shallow charging and discharging, and as a result, the battery deteriorated, but the discharge was stopped in the middle of the discharge that was the reduction process. Sometimes the memory effect is contradictory. In view of the above problems, the present inventors have conducted detailed studies on the production of γ-NiOOH in batteries using β-NiOOH as an active material, such as nickel-hydrogen batteries and nickel-cadmium batteries. As a result, in nickel hydride batteries, nickel cadmium batteries and other batteries using nickel hydroxide as an active material, nickel mesh or the like is usually used as an electrode current collector, and this nickel and β-NiOOH present in the positive electrode after discharge In the open circuit, a local battery having an electrode active material (β-NiOOH) as a positive electrode and an electrode current collector (Ni) as a negative electrode is formed. It was found that γ-NiOOH was produced and the battery was deteriorated.

  The γ-NiOOH produced by the local cell reaction has a diffraction peak at a position of 10.5 to 15 degrees (particularly around 12 degrees) of the diffraction angle 2θ by X-ray diffraction using CuKα rays. On the other hand, γ-NiOOH generated by overcharging also has a diffraction peak at a diffraction angle 2θ of 10.5 to 15 degrees (especially around 12 degrees), and the peak positions are similar, but they are the same substance. It is not clear. This is because the charging process is an oxidation process for the electrode active material (β-NiOOH), whereas the process in which the local battery reaction occurs with the electrode current collector (Ni) is the electrode active material (β This is because -NiOOH) is a reduction process. In this specification, γ-NiOOH generated by overcharging may be expressed as “γox-NiOOH”, and γ-NiOOH generated by local battery reaction may be expressed as “γred-NiOOH”. In this notation, γ-NiOOH in Non-Patent Document 1 is γred-NiOOH. In addition, as described in the battery mail column p.306 to 307 (Battery Handbook 3rd edition, issued on February 20, 2001, Maruzen Co., Ltd.), it appears that the oxidation is more advanced than β-NiOOH that appears in overcharge Γ-NiOOH corresponds to γox-NiOOH. However, at present, there is no report that states that γox-NiOOH and γred-NiOOH are materially different. Therefore, in the present specification, γ-NiOOH is described without distinguishing between the two. However, in order to distinguish whether oxidation is advanced or reduction is advanced, γox- NiOOH or γred-NiOOH may also be described.

Generally, when a battery electrode is an open circuit, a local battery reaction occurs between the electrode material and the electrode supporting metal. In particular, when the battery is not used, the circuit becomes an open circuit and the local battery reaction occurs. By appropriately selecting the electrode support metal, the local battery reaction during open circuit can be controlled. And this time, by making the surface of the electrode current collector not to contain a material having a base electrode potential larger than that of the electrode active material, γ-NiOOH (γred-NiOOH) due to such a local battery reaction. We found that generation can be controlled. Thus, by changing the substance which comprises an electrode, a local cell reaction can be controlled and a memory effect can be suppressed. Furthermore, durability and capacity can be improved by controlling the local battery reaction. These are not limited to alkaline secondary batteries such as nickel metal hydride batteries and nickel cadmium batteries, which have a remarkable memory effect, but also when secondary battery reactions occur in secondary batteries such as lithium batteries and lead storage batteries, and primary batteries. This is a similar improvement because it is possible. The inventors have further studied and completed the present invention. That is, the present invention includes the following configurations.
Item 1. A battery electrode comprising an electrode active material layer comprising an electrode current collector and an electrode active material,
The electrode current collector is made of a material that controls a local battery reaction that occurs between the electrode current collector body and the electrode active material, or occurs between the electrode current collector body and the electrode active material. The electrode for primary batteries or secondary batteries which has the layer which consists of a substance which controls a local battery reaction on the surface.
Item 2. Item 2. The electrode according to Item 1, which is a secondary battery electrode.
Item 3. Item 3. The electrode according to Item 1 or 2, wherein the substance that controls the local battery reaction is a substance that controls the local battery reaction during an open circuit.
Item 4. Item 4. The electrode according to any one of Items 1 to 3, wherein the local battery reaction is the same reaction as an electrode reaction when a battery is used.
Item 5. Item 5. The electrode according to any one of Items 1 to 4, wherein the electrode current collector does not contain a substance having a base electrode potential larger than that of the electrode active material on the surface.
Item 6. Item 6. The electrode according to Item 5, wherein the substance having a large base electrode potential is a substance having a potential equal to or lower than -0.75 V compared to an electrode active material.
Item 7. Item 7. The electrode according to any one of Items 1 to 6, wherein the substance that controls the local battery reaction is a substance having an electrode potential that is larger than the electrode active material and is not base.
Item 8. Item 8. The electrode according to Item 7, wherein the substance having a large and non-base electrode potential is a substance having a potential higher than −0.75 V compared to the electrode active material.
Item 9. Item 9. The electrode according to any one of Items 1 to 8, wherein the substance that controls the local battery reaction is a substance that is electrochemically inert to the electrolyte.
Item 10. Item 1-9, wherein the electrode active material contains at least one selected from the group consisting of nickel hydroxide, β-NiOOH, a lithium-containing transition metal oxide, lithium metal, a carbonaceous material, lead oxide, and manganese dioxide. The electrode according to any one of the above.
Item 11. Item 11. The electrode according to any one of Items 1 to 10, wherein the electrode active material contains nickel hydroxide and / or β-NiOOH.
Item 12. The substance according to Item 7, 8, 10, or 11, wherein the substance having an electrode potential that is larger than the electrode active material and not base contains at least one selected from the group consisting of gold, platinum, silver, iridium and rhodium. electrode.
Item 13. Item 12. The electrode according to any one of Items 9 to 11, wherein the substance that is electrochemically inert to the electrolyte contains at least one selected from the group consisting of a carbonaceous material and a conductive polymer.
Item 14. A primary battery or a secondary battery comprising the electrode according to any one of Items 1 to 13.
Item 15. Item 15. The battery according to Item 14, which is a secondary battery.
Item 16. Item 16. The battery according to Item 14 or 15, which is a nickel metal hydride battery, a nickel cadmium battery, a rechargeable alkaline battery, a lithium ion secondary battery, or a lead storage battery.
Item 17. Item 18. The battery according to any one of Items 14 to 16, which is a nickel metal hydride battery or a nickel cadmium battery.
Item 18. Item 18. The secondary battery according to Item 17, wherein the electrode active material is suppressed from exhibiting a new diffraction peak at a diffraction angle 2θ of 10.5 to 15 degrees by X-ray diffraction using CuKα rays.

  According to the present invention, it is made of a substance that controls the local battery reaction that occurs between the electrode battery assembly and the electrode active material, or the local battery reaction that occurs between the electrode battery assembly and the electrode active material is controlled. An electrode current collector having a layer made of a material to be formed on the surface (specifically, for example, the surface of the electrode current collector does not contain a material having a base electrode potential larger than that of the electrode active material) By using it, such a local battery reaction can be controlled, and the durability and capacity of the primary battery or the secondary battery can be improved. The inclusion of a substance that is larger than the electrode active material and has a base electrode potential includes inclusion of a substance that is electrochemically inactive with respect to the electrolyte. In addition, when a conductive additive is included in the electrode active material layer, the local battery reaction occurring between the electrode current collector and the material on the surface of the conductive additive and the electrode active material is controlled (electrode current collector). The surface of the body and the conductive additive does not contain a substance having a base electrode potential larger than that of the electrode active material), thereby controlling the local battery reaction and improving the durability of the primary battery or the secondary battery. And capacity can be improved. Also in this case, not including a substance having a base electrode potential larger than that of the electrode active material includes containing an electrochemically inactive substance with respect to the electrolyte. In particular, when β-NiOOH is used as an electrode active material, it is possible to suppress the generation of γ-NiOOH (γred-NiOOH), which has conventionally been a cause of the memory effect. By controlling the local battery reaction, the memory effect can be suppressed. Furthermore, durability and capacity can be improved by controlling the local battery reaction. These are not limited to alkaline secondary batteries such as nickel metal hydride batteries and nickel cadmium batteries that have a remarkable memory effect, but are thought to cause local battery reactions in lithium batteries, lead storage batteries, and various primary batteries. It will be the same improvement.

4 is a graph showing the result of X-ray diffraction of β-NiOOH synthesized in Synthesis Example 1. In the synthesis example 1, it is a graph of the result of the X-ray diffraction which shows that (gamma) -NiOOH ((gamma) ox-NiOOH) produces | generates when oxidized excessively. It is an XRD pattern which shows the result of the experiment example 1 of the comparative example 1 (rest 1 day). A peak of γ-NiOOH (γred-NiOOH) is observed at 2θ = 10.5 ° to 15 °. 7 is an XRD pattern showing the result of Experimental Example 1 of Comparative Example 2. FIG. A peak of γ-NiOOH (γred-NiOOH) is observed at 2θ = 10.5 ° to 15 °. The peak is larger than that of Comparative Example 1. It is an XRD pattern which shows the result of Experimental example 1 of Example 1 (rest 1 day). No peak is observed at 2θ = 10.5 ° to 15 °. 6 is an XRD pattern showing the result of Experimental Example 1 of Example 2. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. 6 is an XRD pattern showing the result of Experimental Example 1 of Example 3. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. 6 is an XRD pattern showing the result of Experimental Example 1 of Example 4. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. 7 is an XRD pattern showing the result of Experimental Example 1 of Comparative Example 2. FIG. The difference in pattern due to the difference in standing time is shown. It is a graph which shows the result of Experimental example 2 of the comparative example 1. FIG. The time change of the voltage in process (1), (3) and (6) is shown. 10 is a graph showing the results of Experimental Example 2 of Comparative Example 2. The time change of the voltage in process (1), (3) and (6) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 1. The time change of the voltage in process (3) and (6) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 1. The time change of the voltage in process (3) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 1. The time change of the voltage in process (6) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 2. The time change of the voltage in process (3) and (6) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 3. The time change of the voltage in process (3) and (6) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 3. The time change of the voltage in process (3) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 3. The time change of the voltage in process (6) is shown. 6 is a graph showing the results of Experimental Example 2 of Example 4. The time change of the voltage in process (3) and (6) is shown. 6 is an XRD pattern showing the result of Experimental Example 3 of Example 1. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. 6 is an XRD pattern showing the result of Experimental Example 3 of Example 6. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is an XRD pattern which shows the result of Experimental example 3 of the comparative example 3. A peak of γ-NiOOH (γred-NiOOH) is strongly observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of Experimental example 4 of the comparative example 3. FIG. 10 is a graph showing the results of Experimental Example 4 of Example 6. It is shown that the capacity and potential are larger than those of Comparative Example 3. 6 is a graph showing the results of Experimental Example 5 of Example 1. There was no potential drop in the discharge curve after the rest. 10 is a graph showing the results of Experimental Example 5 of Example 2. There was no potential drop in the discharge curve after the rest. 10 is a graph showing the results of Experimental Example 5 of Example 3. There was no potential drop in the discharge curve after the rest. It is a graph which shows the result of the cycle charging / discharging test (no rest time; 5 cycles) of Experimental example 6 of Example 1. The curve is from the first cycle to the fifth cycle in order from the bottom. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 5 cycles) of Experimental example 6 of Example 1. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no downtime; 5 cycles) of Experimental example 6 of Example 2. The curve is from the first cycle to the fifth cycle in order from the bottom. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 5 cycles) of Experimental example 6 of Example 2. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no downtime; 5 cycles) of Experimental example 6 of Comparative example 1. The curve is from the first cycle to the fifth cycle in order from the top at the right end. It is a graph which shows the result of the X-ray-diffraction measurement (there is no rest time; 5 cycles) of Experimental example 6 of the comparative example 1. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no downtime; 5 cycles) of Experimental example 6 of Example 3. The curve is from the first cycle to the fifth cycle in order from the bottom. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 5 cycles) of Experimental example 6 of Example 3. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no downtime; 10 cycles) of Experimental example 6 of Example 1. The curve is from the first cycle to the tenth cycle in order from the bottom. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 10 cycles) of Experimental example 6 of Example 1. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no downtime; 10 cycles) of Experimental example 6 of Example 2. The curves are from the first cycle to the tenth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 10 cycles) of Experimental example 6 of Example 2. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no rest time; 10 cycles) of Experimental example 6 of Comparative example 1. The curve is from the first cycle to the tenth cycle in order from the top at the right end. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 10 cycles) of Experimental example 6 of the comparative example 1. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (no downtime; 10 cycles) of Experimental example 6 of Example 3. The curve is from the first cycle to the tenth cycle in order from the bottom. It is a graph which shows the result of the X-ray-diffraction measurement (no rest time; 10 cycles) of Experimental example 6 of Example 3. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 5 cycles) of Experimental example 6 of Example 1. The curve is from the first cycle to the fifth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 5 cycles) of Experimental example 6 of Example 1. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 5 cycles) of Experimental example 6 of Example 2. The curve is from the first cycle to the fifth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 5 cycles) of Experimental example 6 of Example 2. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 5 cycles) of Experimental example 6 of Comparative Example 1. The curve is from the first cycle to the fifth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 5 cycles) of Experimental example 6 of the comparative example 1. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 5 cycles) of Experimental example 6 of Example 3. The curve is from the first cycle to the fifth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 5 cycles) of Experimental example 6 of Example 3. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 10 cycles) of Experimental example 6 of Example 1. The curve is from the first cycle to the tenth cycle in order from the top at the right end. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 10 cycles) of Experimental example 6 of Example 1. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 10 cycles) of Experimental example 6 of Example 2. The curve is in the first cycle to the tenth cycle in order from the top at the right end, and a voltage drop was observed in the 10th cycle. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 10 cycles) of Experimental example 6 of Example 2. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 1 hour; 10 cycles) of Experimental example 6 of Example 3. The curves are from the first cycle to the tenth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (resting 1 hour; 10 cycles) of Experimental example 6 of Example 3. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 2 hours; 5 cycles) of Experimental example 6 of Example 1. The curves are from the first cycle to the fifth cycle in order from the top, and a voltage drop was observed at the fifth cycle. It is a graph which shows the result of the X-ray-diffraction measurement (resting 2 hours; 5 cycles) of Experimental example 6 of Example 1. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 2 hours; 5 cycles) of Experimental example 6 of Example 2. The curves are from the first cycle to the fifth cycle in order from the top, and a voltage drop was observed at the fifth cycle. It is a graph which shows the result of the X-ray-diffraction measurement (resting 2 hours; 5 cycles) of Experimental example 6 of Example 2. FIG. No peak is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 2 hours; 5 cycles) of Experimental example 6 of Comparative example 1. The curves are from the first cycle to the fifth cycle in order from the top, and a voltage drop was observed at the second cycle. It is a graph which shows the result of the X-ray-diffraction measurement (resting 2 hours; 5 cycles) of Experimental example 6 of the comparative example 1. A peak of γ-NiOOH is observed at 2θ = 10.5 ° to 15 °. It is a graph which shows the result of the cycle charging / discharging test (resting 2 hours; 5 cycles) of Experimental example 6 of Example 3. The curve is from the first cycle to the fifth cycle in order from the top. It is a graph which shows the result of the X-ray-diffraction measurement (resting 2 hours; 5 cycles) of Experimental example 6 of Example 3. FIG. No peak is observed at 2θ = 10.5 ° to 15 °.

1. Primary battery or secondary battery electrode The primary battery or secondary battery electrode of the present invention is an electrode current collector and a battery electrode comprising an electrode active material layer containing an electrode active material, the electrode current collector Is made of a material that controls a local battery reaction that occurs between the electrode current collector and the electrode active material, or controls a local battery reaction that occurs between the electrode current collector and the electrode active material (In particular, the substance that controls the local battery reaction is preferably a substance that controls the local battery reaction during open circuit). Specifically, it is preferable that the electrode current collector does not contain a substance having a base electrode potential larger than that of the electrode active material on the surface. When the electrode active material layer contains a conductive additive, additive, etc., the material on the surface of the electrode current collector, the substance on the surface of the conductive additive, additive, etc., and the electrode active material It is preferable to control the local battery reaction that occurs in the middle (the surface of the electrode current collector and the conductive additive does not contain a substance having a base electrode potential larger than that of the electrode active material).

<Electrode current collector>
As described above, the electrode current collector is formed on the surface, the electrode current collector is made of a material that controls a local battery reaction that occurs between the electrode current collector and the electrode active material, or the electrode The surface has a layer made of a substance that controls a local battery reaction that occurs between the current collector and the electrode active material. In order to control this local battery reaction, it is preferable that the electrode current collector does not contain a material having a base electrode potential larger than that of the electrode active material. Thus, it has a layer made of a substance that controls the local battery reaction or a substance that controls the local battery reaction on its surface (in particular, a substance having a base electrode potential larger than that of the electrode active material) Is not included in the surface of the electrode current collector), so that when the circuit is open, for example, when the battery is not used, the electrode active material (β-NiOOH, etc.) is the positive electrode and the electrode current collector (Ni, etc.) is the negative electrode It is possible to control the generation of the battery and suppress the deterioration of the battery due to the local battery reaction.

  Such an electrode current collector is composed of a material having an electrode potential that is larger than the electrode active material and / or an electrode that is electrochemically inactive with respect to the electrolyte, or more than the electrode active material. It is preferable to have on the surface a layer made of a substance having a large and non-base electrode potential and / or a substance that is electrochemically inert to the electrolyte. In addition, when using conductive assistants, additives, etc., the conductive assistants, additives, etc. are also electrochemically inactive with respect to substances and / or electrolytes having electrode potentials that are larger than the electrode active material and not base. It is preferable that the surface has a layer made of a material which is made of a non-base material or has a non-base electrode potential larger than that of the electrode active material and / or a material which is electrochemically inert to the electrolyte. By adopting such a configuration, the reaction of the local battery with the electrode active material (β-NiOOH, etc.) as the positive electrode and the electrode current collector (Ni, etc.) as the negative electrode is more reliably controlled during open circuit. Thus, it is possible to improve durability and capacity by suppressing deterioration of the electrode material due to the local battery reaction.

  As used herein, the term “substance having an electrode potential larger than that of the electrode active material” is not limited to the substance having an electrode potential not significantly lower than the electrode potential of the electrode active material. In contrast, an electrochemically inactive substance is also included. Such a substance is not particularly limited, but is preferably a substance having a potential higher than −0.75 V, more preferably a substance higher than −0.50 V, and −0. Substances higher than 25V are more preferred, and substances higher than 0V are particularly preferred. Further, “a substance that is electrochemically inactive with respect to the electrolyte” can also be preferably used. On the other hand, it is preferable that the “substance having a base electrode potential larger than that of the electrode active material” does not include a material having a potential equal to or lower than −0.75 V compared to the electrode active material. Specifically, taking as an example a positive electrode using nickel hydroxide as an active material, such as a nickel metal hydride battery or a nickel cadmium battery positive electrode, it is generated when a nickel metal hydride battery, a nickel cadmium battery positive electrode or the like is charged. Compared with β-NiOOH (+0.52 V vs SHE), lead, copper, gold (monovalent), platinum, silver, iridium, rhodium, etc. having a potential higher than −0.75 V are preferable, and the potential is −0.25 V. Higher copper, gold (monovalent), platinum, silver, iridium, rhodium and the like are more preferable, and gold (monovalent), platinum, silver, iridium, rhodium and the like having a potential higher than 0 V are particularly preferable. In addition, the “electrochemically inactive substance with respect to the electrolyte” means that when the electrolyte is an aqueous solution system such as an aqueous potassium hydroxide solution or an aqueous sulfuric acid solution, carbonaceous materials, conductive polymers (especially conductive organic polymers) Molecule) and the like can be preferably used. As the carbonaceous material, there is no particular limitation, and carbon black such as channel black, furnace black, ketjen black, acetylene black, and lamp black; graphite such as natural graphite and artificial graphite; activated carbon; amorphous carbon and the like can be preferably employed. The conductive polymer is not particularly limited, and polythiophene, polyacetylene, polyaniline, polypyrrole, polythiazyl, and the like can be preferably used. These substances may be included singly or in combination of two or more.

  On the other hand, it is preferable that nickel, titanium, lithium, potassium, iron, zinc or the like whose potential is lower than −0.75 V compared to the standard electrode potential of β-NiOOH is not present on the surface of the electrode current collector. Moreover, when using a conductive support agent, an additive, etc., it is preferable not to have these substances also on the surfaces, such as a conductive support agent, an additive.

The standard electrode potential of each substance, respectively, lithium ^{(Li + + e - → Li} ; -3.04 V vs SHE), potassium ^{(K + + e - → K} ; -2.925 V vs SHE), titanium (Ti ^{2 +} + 2e ⁻ → Ti; −1.63 V vs SHE), zinc (Zn ²⁺ + 2e ⁻ → Zn; −0.763 V vs SHE), iron (Fe ²⁺ + 2e ⁻ → Fe; −0.440 V vs SHE), Nickel (Ni ²⁺ + 2e ⁻ → Ni; −0.257 V vs SHE), Lead (Pb ²⁺ + 2e ⁻ → Pb; −0.126 V vs SHE), Copper (Cu ²⁺ + e ⁻ → Cu ⁺ ; +0.337 V vs SHE), rhodium (Rh ³⁺ + 3e ⁻ → Rh; + 0.758V vs SHE), silver (Ag ⁺ + e ⁻ → Ag; +0.799 V vs SHE), iridium (Ir ³⁺ + 3e ⁻ → Ir + 1.156 V vs SHE), platinum (Pt ²⁺ + 2e ⁻ → Pt; + 1.188 V vs SHE), gold (monovalent) (Au ⁺ + e ⁻ → Au; + 1.83 V vs SHE).

  When an electrode current collector having a layer made of a material having an electrode potential larger than that of the electrode active material and not negative and / or a material that is electrochemically inactive with respect to the electrolyte is employed, The part may be a substance having an electrode potential which is larger than the electrode active material and not base, or may be a substance which has a base electrode potential larger than the electrode active material. Further, it may be a substance that is electrochemically inactive with respect to the electrolyte. In other words, even a substance having a base electrode potential larger than that of the electrode active material is electrochemically inactive with respect to a substance and / or electrolyte having an electrode potential larger than that of the electrode active material on the surface thereof. If a layer made of a material is formed, it can be used as an electrode current collector. In this case, “form a layer made of a substance having an electrode potential that is larger than the electrode active material and is not base on the surface and / or a substance that is electrochemically inactive to the electrolyte” means that the surface is the above-mentioned specific substance It is not necessary to be completely covered with a layer made of the above, and includes the case where the specific substance is scattered on the surface. For this reason, an inexpensive material is used as the electrode active material, and a layer made of a material that has an electrode potential larger than the electrode active material and is not base on the surface and / or a material that is electrochemically inert to the electrolyte (particularly By forming an inexpensive carbonaceous material, a conductive polymer, or the like, the primary battery or secondary battery electrode of the present invention can be manufactured at a lower cost.

  The thickness of the layer made of a substance having an electrode potential larger than that of the electrode active material and / or an electrochemically inert substance with respect to the electrolyte is not particularly limited, but the electrode material is deteriorated by a local battery reaction. From the viewpoint of more reliably suppressing the durability and further improving the durability and capacity, 5 nm to 10 mm is preferable, and 10 nm to 1 mm is more preferable.

  There is no particular limitation on the method for forming a layer made of a substance having an electrode potential larger than that of the electrode active material and / or an electrode inactive to the electrolyte on the surface of the electrode current collector. For example, a coating method, a plating method, a vapor deposition method, or the like can be employed. When adopting the coating method, for example, it can be applied by means of roller coating such as applicator roll; screen coating; doctor blade method; spin coating; Moreover, when employ | adopting a plating method, any of electrolytic plating and electroless plating may be sufficient.

<Electrode active material layer>
The electrode active material in the electrode active material layer is not particularly limited, and a material conventionally used for a positive electrode or a negative electrode of a primary battery or a secondary battery can be used.

  Specifically, for a nickel metal hydride battery, a nickel cadmium battery, a rechargeable alkaline battery, etc., the primary battery or secondary battery electrode of the present invention should be used as a positive electrode from the viewpoint of further suppressing deterioration due to a local battery reaction. In this case, it is preferable to employ nickel hydroxide usually used as a positive electrode active material, β-NiOOH formed during charging, manganese dioxide, or the like.

For a lithium ion secondary battery or the like, the primary battery or secondary battery electrode of the present invention may be used for either the positive electrode or the negative electrode. When used as a positive electrode, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiFePO _4, LiNi _x Mn _y Co _z O ₂ (0 <x, 0 <y, 0 <z, x + y + z) used as a positive electrode active material. = 1) and other lithium-containing transition metal oxides can be employed. When used as a negative electrode, lithium metal used as a negative electrode active material, natural graphite, graphite such as artificial graphite, activated carbon, etc. Lithium-containing transition metal oxides such as carbonaceous materials, Li _v Ti _w O ₄ (0 <v, 0 <w, v + w = 3) can be employed.

  It is preferable to use the electrode for the primary battery or the secondary battery of the present invention as a positive electrode for a lead storage battery or the like from the viewpoint of further suppressing deterioration due to a local battery reaction. In this case, lead oxide usually used as a positive electrode active material Etc. can be adopted.

  Although only the example about the secondary battery has been described above, the electrode of the present invention can be used for various primary batteries.

  Among these, nickel hydroxide, β-NiOOH, and the like are preferable in nickel-metal hydride batteries, nickel-cadmium batteries, and the like that have a remarkable memory effect because they can suppress battery deterioration and further improve durability and capacity. .

  The content of these electrode active materials in the electrode active material layer is not particularly limited, and conventionally applied to the primary battery or secondary battery positive electrode or negative electrode employing the primary battery or secondary battery electrode of the present invention. Can be as much as possible.

<Conductive aid>
In the present invention, the electrode active material layer may contain a conductive additive.

  As a conductive support agent, it is preferable to employ | adopt the material which is an electron conductive material and can control a local battery reaction. Specifically, graphite such as natural graphite, artificial graphite, etc .; carbon black; acetylene black; ketjen black; carbon whisker; carbon fiber; Can do.

  In addition, the electrode active material layer may contain a binder, a thickener, and the like in addition to the above components.

  The binder is usually a thermoplastic resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyethylene, polypropylene; ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR). Polymers having rubber elasticity such as fluoro rubber can be used as one kind or a mixture of two or more kinds. The addition amount of the binder is preferably about 2 to 15% by mass with respect to the total mass of the negative electrode active material layer.

  As the thickener, polysaccharides such as carboxymethylcellulose and methylcellulose can be used as one kind or a mixture of two or more kinds.

  These mixing methods are physical mixing, and uniform mixing is preferable. Therefore, it is possible to use a powder mixer such as a V-type mixer, an S-type mixer, a grinder, a ball mill, a planetary ball mill, etc., dry or wet.

  In the present invention, the method for forming the electrode active material layer on the electrode current collector is not particularly limited. For example, various components such as an electrode active material are mixed with water to prepare a paste composition for forming an electrode (positive electrode or negative electrode) active material layer, and then the electrode collector is impregnated with the paste composition or The method of apply | coating and drying is mentioned.

  About the application method, it can apply using means, such as roller coating, such as an applicator roll; Screen coating; Doctor blade system; Spin coating; Bar coater. Moreover, there is no restriction | limiting in particular also in drying conditions, It can employ | adopt in the range normally employ | adopted in the primary battery or the secondary battery.

2. Primary battery or secondary battery The primary battery or secondary battery of the present invention includes the primary battery or secondary battery electrode of the present invention. Hereinafter, the configuration of each battery will be described.

<Alkaline secondary battery>
When the electrode of the present invention is used for an alkaline secondary battery such as a nickel metal hydride battery, a nickel cadmium battery, or a rechargeable alkaline battery, nickel hydroxide (β-NiOOH at the time of charging), manganese dioxide, etc. are used as the electrode active material. The electrode of the present invention is preferably used as a positive electrode.

  Examples of other members include a negative electrode, an electrolytic solution, and a separator. These may be produced as appropriate or may be commercially available, and members and materials in known alkaline secondary batteries such as nickel metal hydride batteries and nickel cadmium batteries can be employed. Among these materials, the negative electrode material is preferably a hydrogen storage alloy in the case of a nickel metal hydride battery, or cadmium hydroxide in the case of a nickel cadmium battery. Moreover, as a material of the electrolytic solution, a potassium hydroxide aqueous solution or the like is preferable.

The hydrogen storage alloy is not particularly limited, and those conventionally used as a negative electrode active material for nickel metal hydride batteries can be used. For example, an alloy capable of storing hydrogen and may be an alloy generally referred to as an AB ₂ system, an AB ₅ system, or an AB ₂ and AB ₅ mixed system, and the composition thereof is not particularly limited. Among these, AB ₅ type alloy MHNi ₅ (MH is a mixture of rare earth elements (Misch metal)), a part of Ni is replaced with Co, Mn, Al, Cu, etc., alloy has excellent charge / discharge cycle life It is preferable because of its characteristics and high discharge capacity.

  In the case of a nickel metal hydride battery or a nickel cadmium battery, this alkaline secondary battery can control the local battery reaction and suppress the production of γ-NiOOH (γred-NiOOH). It is suppressed that a new diffraction peak is shown at a position of 10.5 to 15 degrees of the folding angle 2θ.

<Lithium ion secondary battery>
In the lithium ion secondary battery, the electrode of the present invention can be used for both the positive electrode and the negative electrode, and preferably used for both.

  Examples of other members include an electrolytic solution and a separator. These may be produced as appropriate or may be commercially available, and members and materials in known lithium batteries can be employed.

<Lead battery>
When the electrode of the present invention is used for a lead storage battery, it is preferable to employ lead dioxide as the electrode active material and to use the electrode of the present invention as a positive electrode.

  Examples of other members include a negative electrode, an electrolytic solution, and a separator. These may be produced as appropriate or may be commercially available, and members and materials in known lead-acid batteries can be employed.

  In addition, the electrode of the present invention can be preferably used for a well-known primary battery electrode (positive electrode or negative electrode). In this case, other known members may be employed.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

[Synthesis Example 1: Synthesis of β-NiOOH]
Synthesis was performed using commercially available Ni (OH) ₂ and NaClO according to the following reaction formula.
Reaction formula: 2Ni (OH) ₂ + NaClO → 2NiOOH + NaCl + H ₂ O.

To 0.4 g of Ni (OH) ₂ added 10 ml of distilled water to make a slurry, adjust the pH to 13 or more by adding 10 ml of NaClO and 10 ml of 8M aqueous sodium hydroxide, and adjust the temperature using a hot stirrer. The mixture was kept at 20 ° C. and reacted for 1 hour 30 minutes with stirring. This was subjected to suction filtration and then dried in air at 40 ° C. for 1 day.

  When X-ray diffraction measurement was performed using CuKα rays, a diffraction pattern as shown in FIG. 1 was obtained, and characteristic peaks at 2θ = about 19 ° and about 38 ° were observed. In addition, it was judged that β-NiOOH was obtained instead of γ-NiOOH because no peak was observed at 2θ = 10.5 ° to 15 ° and no large peak was observed on the higher angle side than 2θ = 40 °. . This pattern is consistent with the pattern in Fig. 3 of J. Pan et al. / Electrochemica Acta 54 (2009) 3812-3818.

  When the reaction time was increased under the same conditions, a peak appeared in the XRD pattern between 2θ = 10.5 ° and 15 ° as shown in FIG. This pattern is similar to the γ-NiOOH peak in Fig. 3 of J. Pan et al. / Electrochemica Acta 54 (2009) 3812-3818, and it was found that γ-NiOOH (γox-NiOOH) was produced. .

From the above results, it was found that β-NiOOH was produced by oxidizing Ni (OH) ₂ and γ-NiOOH (γox-NiOOH) was produced by excessive oxidation.

[Comparative Example 1: Nickel mesh]
Β-NiOOH prepared in Synthesis Example 1 was added with acetylene black as a conductive additive, PTFE as a binder, and β-NiOOH: acetylene black: binder with a ratio of 80: 15: 5 (mass%), respectively. The resulting mixture was mixed well to prepare a paste composition for forming a positive electrode active material layer.

  As the positive electrode support (electrode current collector), nickel mesh (manufactured by Nilaco Co., Ltd .; nickel wire mesh 100mesh) is used, and the positive electrode support has a thickness of 0.1 to 10 mm (particularly 1 mm). The active material layer forming paste composition was applied and dried to obtain a positive electrode for secondary battery of Comparative Example 1.

[Comparative Example 2: Titanium mesh]
For the secondary battery of Comparative Example 2 as in Comparative Example 1, except that titanium mesh (made by Nilaco Co., Ltd .; titanium wire mesh 100mesh) was used as the positive electrode support (electrode current collector) instead of nickel mesh. A positive electrode was obtained.

[Example 1: Gold mesh]
For the secondary battery of Example 1, as in Comparative Example 1, except that a gold mesh (manufactured by Nilaco Co., Ltd .; wire mesh 100 mesh) was used as the positive electrode support (electrode current collector) instead of nickel mesh. A positive electrode was obtained.

[Example 2: Platinum mesh]
For the secondary battery of Example 2 as in Comparative Example 1, except that platinum mesh (made by Nilaco Co., Ltd .; platinum mesh 100 mesh) was used as the positive electrode support (electrode current collector) instead of nickel mesh. A positive electrode was obtained.

[Example 3: Carbon coated nickel mesh]
Using an E-1010 Hitachi Ion Sputter, starting with an additional current of 20 A and continuing to vaporize for about 10 seconds until this reached 0 A, a carbon-coated nickel mesh was obtained. The film thickness at this time is 12 nm according to the manual.

  A positive electrode for a secondary battery of Example 3 was obtained in the same manner as in Comparative Example 1 except that a carbon-coated nickel mesh was used instead of a nickel mesh as a positive electrode support (electrode current collector).

[Example 4: Carbon coated titanium mesh]
Using an E-1010 type Hitachi ion sputter, starting with an additional current of 20A and continuing to vaporize for about 10 seconds until it reached 0A, a carbon coated titanium mesh was obtained. The film thickness at this time is 12 nm according to the manual.

  A positive electrode for a secondary battery of Example 4 was obtained in the same manner as in Comparative Example 1 except that a carbon coated titanium mesh was used instead of a nickel mesh as a positive electrode support (electrode current collector).

[Experimental Example 1: Formation of γ-NiOOH (γred-NiOOH) at rest]
The positive electrodes for the secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 2 were each used as a working electrode, Pt as a counter electrode, an Ag / AgCl reference electrode as a reference electrode, 8M KOH as an electrolyte, and a glass cell (2 Secondary battery).

After discharging to the middle of a plateau of +0.5 to +0.35 V (vs SHE) (region with a small potential change), it was left in an open circuit state. About Examples 1-4 and Comparative Examples 1-2, the XRD pattern of the positive electrode material after various time progress is as follows:
Fig. 3 Comparative Example 1 (nickel mesh) 1 day later Fig. 4 Comparative Example 2 (titanium mesh) 2 days later Fig. 5 Example 1 (gold mesh) 1 day later Fig. 6 Example 2 (platinum mesh) 3 days later Fig. 7 Example 3 ( Carbon coated nickel mesh) FIG. 8 after one day Example 4 (carbon coated titanium mesh) Shown after one day.

  When attention is paid to a pattern of 2θ of 10.5 ° to 15 °, a peak appeared in Comparative Examples 1 and 2 using a nickel mesh and a titanium mesh as an electrode support (electrode current collector) (FIGS. 3 to 4). . Titanium with a lower standard electrode potential than nickel had a larger peak.

  Moreover, it experimented similarly about the titanium mesh of the comparative example 2, and the XRD pattern in stationary time 30 minutes and 1 hour is shown in FIG. As the standing time increased, the intensity of this peak increased.

  Y. Sato et al./Journal of Power Sources 93 (2001) 20-24 describes that this is the peak of γ-NiOOH. It is also described that the production of γ-NiOOH is the cause of the memory effect. The γ-NiOOH produced by the local battery reaction has a diffraction peak at a position of 10.5 to 15 degrees in the diffraction angle 2θ by X-ray diffraction using CuKα rays. On the other hand, γ-NiOOH generated by overcharging also has a diffraction peak at a diffraction angle 2θ of 10.5 to 15 degrees, and the peak positions are similar, but it is not clear whether or not they are the same substance. This is because the charging process is an oxidation process for the electrode active material (β-NiOOH), while the local battery reaction with the electrode current collector (Ni) occurs in the electrode active material (β This is because -NiOOH) is a reduction process. Γ-NiOOH in this document can be expressed as γ-NiOOH (γred-NiOOH). Γ-NiOOH as a state of oxidation more advanced than β-NiOOH that appears in overcharge can be expressed as γ-NiOOH (γox-NiOOH). However, at present, there is no report that states that γox-NiOOH and γred-NiOOH are materially different.

  On the other hand, in Examples 1-2 using a gold mesh and a platinum mesh as an electrode support (electrode current collector), this peak did not appear (FIGS. 5-6). The potential of β-NiOOH is +0.52 V with respect to a standard hydrogen electrode (SHE) in a fully charged state (Source: Overview of Panasonic Corporation Rechargeable Nickel Metal Hydride Battery). Nickel and titanium have a large base potential with respect to β-NiOOH. In contrast, gold and platinum have large non-base potentials.

  When the battery cell is opened, a local battery reaction based on the potential difference occurs between the electrode material (electrode active material) in the electrode and the electrode support (electrode current collector). In this local battery, when the electrode support is a nickel mesh or titanium mesh (Comparative Examples 1 and 2), β-NiOOH is a positive electrode, and the electrode support (electrode current collector) is a gold mesh or a platinum mesh. In Examples 1 and 2, β-NiOOH serves as a negative electrode. When the electrode support (electrode current collector) is a nickel mesh or a titanium mesh (Comparative Examples 1 and 2), γ-NiOOH (γred-NiOOH) was generated. It has been found that “γ-NiOOH (γred-NiOOH)” is produced when acting as a positive electrode.

  On the other hand, even when the electrode support (electrode current collector) is a nickel mesh or titanium mesh produced by γ-NiOOH (γred-NiOOH), when carbon coating is performed (Examples 3 to 4), The peak of “γ-NiOOH (γred-NiOOH)” did not appear. Since carbon is inactive in this electrolyte, local cell reaction does not occur, β-NiOOH does not act as a positive electrode, and the electrode support (electrode current collector) is a gold mesh or platinum mesh. It can be said that “γ-NiOOH (γred-NiOOH)” was not generated as in (Examples 1 and 2). As described above, in a secondary battery using nickel hydroxide as an electrode active material, such as a nickel metal hydride battery or a nickel cadmium secondary battery, an electrode for controlling a local battery reaction in which β-NiOOH acts as a positive electrode is “γ It can be seen that the production of “-NiOOH (γred-NiOOH)” can be prevented. It was also shown that the electrode reaction of nickel and titanium can be shielded by coating with carbon. It is considered that the electrode reaction can be shielded even when coated with a conductive polymer or the like other than carbon.

[Experimental example 2: Memory effect and difference in capacity (1)]
Similarly to Experimental Example 1, the positive electrodes for secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were used as working electrodes, respectively, and glass cells (secondary batteries) were produced in the same manner as in Experimental Example 1.

The following process:
(1) +0.5 to +0.35 V (vs SHE) until the end of the plateau (2) 6-hour charge (3) + 0.5 to +0.35 V (vs SHE) halfway to the plateau (4) Pause (Comparative example) 1 (nickel mesh): 1 week, Examples 1 to 4 and Comparative Example 2 (others): 5 hours)
(5) Charging for 6 hours (6) Charging / discharging according to discharging until the end of the plateau of +0.5 to +0.35 V (vs SHE) was performed in this order at a current density of 30 mA / g.

  It should be noted that both (2) and (5) are fully charged.

For Examples 1 to 4 and Comparative Examples 1 to 2, the time variation of voltage in various processes is as follows:
FIG. 10 Comparative Example 1 (Nickel Mesh) Process (1), (3), (6)
FIG. 11 Comparative Example 2 (titanium mesh) Process (1), (3), (6)
FIG. 12 Example 1 (gold mesh) Process (3), (6)
FIG. 13 Example 2 (platinum mesh) Process (3), (6)
FIG. 14 Example 3 (carbon coated nickel mesh) Process (3), (6)
FIG. 15 Example 4 (carbon coated titanium mesh) Process (3), (6)
Shown in

  When the electrode support was made of nickel mesh or titanium mesh (Comparative Examples 1 and 2), a phenomenon was observed in which the voltage in the process of (6) rapidly decreased compared to the process of (1). This represents the memory effect. On the other hand, when the gold mesh, the platinum mesh, the nickel mesh subjected to carbon coating, and the titanium mesh subjected to carbon coating (Examples 1 to 4), the voltage in the process of (6) is (3). Compared to the process, it did not decrease rapidly.

  From the above results, a memory effect was observed when an electrode support that causes a local battery reaction in which β-NiOOH acts as a positive electrode in Experimental Example 1 was used. From the above, in secondary batteries using nickel hydroxide as an electrode active material, such as nickel metal hydride batteries and nickel cadmium secondary batteries, the electrode that controls the local battery reaction in which β-NiOOH acts as the positive electrode has a memory effect. It can be seen that the durability can be improved without causing any problems.

  Further, when the elapsed time is compared, when the gold mesh, the platinum mesh, the carbon coated nickel mesh, or the carbon coated titanium mesh is used as the electrode support (Examples 1 to 4), the electromotive force is remarkably reduced to 10,000 to 10,000. It is about 25000 seconds. On the other hand, when nickel mesh or titanium mesh is used, it takes about 3000 to 13000 seconds. In particular, when Comparative Example 2 and Example 4 using the same titanium as the electrode current collector are compared, the time during which the electromotive force is remarkably reduced jumps from about 3000 seconds to about 10,000 seconds by applying the carbon coat. Has improved. In other words, it can be seen that the capacity of the battery is also dramatically improved. From this, when nickel mesh or titanium mesh is used (Comparative Examples 1 and 2), even when a normal battery is used, the local battery reaction that occurs in parallel acts to reduce the capacity of the battery. The secondary battery electrode of the present invention can suppress this effect.

[Example 5: Gold mesh (conductive auxiliary nickel; starting material Ni (OH) ₂ )]
Commercially available Ni (OH) commercial Ni metal powder as ₂ to conductive additive (Ni powder), the PTFE as a binder, Ni (OH) _2: acetylene black: binder 80: 15: 5 (mass %)) And mixed well to prepare a paste composition for forming a positive electrode active material layer.

  As a positive electrode support (electrode current collector), a gold mesh (manufactured by Nilaco Co., Ltd .; wire mesh 100 mesh) was used, and the positive electrode support was adjusted so that the thickness was 0.1 to 10 mm (particularly 1 mm). The paste composition for forming an active material layer was applied and dried to obtain a positive electrode for a secondary battery of Example 5.

[Example 6: Gold mesh (conductive auxiliary agent acetylene black; starting material Ni (OH) ₂ )]
A positive electrode for a secondary battery of Example 6 was obtained in the same manner as in Example 5 except that acetylene black was used instead of Ni metal powder as the conductive additive.

[Comparative Example 3: Nickel mesh (conductive auxiliary agent acetylene black; starting material Ni (OH) ₂ )]
Nickel mesh (made by Nilaco Co., Ltd .; nickel wire mesh 100mesh) was used as the positive electrode support (electrode current collector) instead of gold mesh, and acetylene black was used as the conductive auxiliary agent instead of Ni metal powder. A secondary battery positive electrode of Comparative Example 3 was obtained in the same manner as Example 5 except for the above.

[Experimental example 3: X-ray diffraction measurement result when resting during discharge]
<In case of β-NiOOH starting material>
Similarly to Experimental Example 1, a positive electrode for a secondary battery of Example 1 (gold mesh) was used as a working electrode, and a glass cell (secondary battery) was produced in the same manner as in Experimental Example 1.

The following process:
(1) Discharge until plateau of +0.5 to +0.35 V (vs SHE) (2) Charge for 6 hours (3) Discharge until halfway of plateau of +0.5 to +0.35 V (vs SHE) (4) Rest for 3 days Therefore, charging and discharging were all performed in this order at a current density of 30 mA / g.

  The results are shown in FIG. As a result, no peak of γ-NiOOH was observed.

<In the case of starting material Ni (OH) ₂ >
Similarly to Experimental Example 1, the positive electrode for the secondary battery of Example 6 and Comparative Example 3 (gold mesh and nickel mesh) was used as the working electrode, respectively, and a glass cell (secondary battery) was produced in the same manner as in Experimental Example 1. .

The following process:
(1) Charging for 6 hours (2) Discharging until completion of the plateau of +0.5 to +0.35 V (vs SHE) * (1) and (2) were repeated three times.
(3) Charging for 6 hours (4) Discharging to the middle of the plateau of +0.5 to +0.35 V (vs SHE) (5) Charging / discharging according to one week of rest was performed in this order at a current density of 30 mA / g. .

For Example 6 and Comparative Example 3, the XRD patterns of the positive electrode material after various time elapsed are as follows:
FIG. 17 Example 6 (gold mesh; starting material Ni (OH) ₂ )
FIG. 18 Comparative Example 3 (nickel mesh; starting material Ni (OH) ₂ )
Shown in

  As a result, the peak of γ-NiOOH was seen in Comparative Example 3, but the peak of γ-NiOOH was not seen in Example 6.

[Experimental Example 4: Difference in capacity]
Similarly to Experimental Example 1, the positive electrodes for secondary batteries of Example 6 and Comparative Example 3 were used as working electrodes, respectively, and a glass cell (secondary battery) was produced in the same manner as in Experimental Example 1.

The following process:
(1) Charging for 6 hours (2) Discharging until completion of the plateau of +0.5 to +0.35 V (vs SHE) * (1) and (2) were repeated three times.
Accordingly, charging and discharging were performed in this order at a current density of 30 mA / g.

The discharge curve in each final discharge process is shown in FIG. 19 Comparative Example 3 (nickel mesh; starting material Ni (OH) ₂ )
FIG. 20 Example 6 (gold mesh; starting material Ni (OH) ₂ )
Shown in

As a result, even when Ni (OH) ₂ is used as the starting material, the capacity and potential are higher when the gold mesh is used than when the nickel mesh is used as the electrode current collector. I understand.

[Experiment 5: Difference in memory effect]
Similarly to Experimental Example 1, each of the positive electrodes for secondary batteries of Examples 1 to 3 was used as a working electrode, and similarly to Experimental Example 1, a glass cell (secondary battery) was produced.

The following process:
(1) Discharge until the end of the plateau of +0.5 to +0.35 V (vs SHE) (2) Charge for 6 hours (3) Discharge to the middle of the plateau of +0.5 to +0.35 V (vs SHE) (4) Rest for 1 week ( 5) Charging for 6 hours (6) Charging / discharging according to discharging until the end of the plateau of +0.5 to +0.35 V (vs. SHE) was performed in this order at a current density of 30 mA / g.

  It should be noted that both (2) and (5) are fully charged.

For Examples 1-3, the time variation of voltage in various processes is as follows:
FIG. 21 Example 1 (gold mesh)
FIG. 22 Example 2 (platinum mesh)
FIG. 23 Example 3 (carbon coated nickel mesh)
Shown in

  In either case, no potential drop in the discharge curve was observed after the pause.

[Experimental Example 6: Cycle Charge / Discharge Test with Rest]
<No downtime (0 hours)>
Similarly to Experimental Example 1, the positive electrodes for secondary batteries of Examples 1 to 3 and Comparative Example 1 were used as working electrodes, respectively, and a glass cell (secondary battery) was produced in the same manner as in Experimental Example 1.

The following process:
Process I (normal charge / discharge):
(1) Discharge until the end of the plateau of +0.5 to +0.35 V (vs SHE) (2) Charge for 6 hours * (1) and (2) were repeated three times.
Process II (SOC discharge to 40%):
(3) 2-hour discharge process III (SOC 40-60% charge / discharge):
(4) Charging for 50 minutes (5) Discharging for 40 minutes * (4) and (5) were repeated 5 times or 10 times (5 cycles or 10 cycles).
Accordingly, charging and discharging were performed in this order at a current density of 30 mA / g.

  By making the charging time longer than the discharging time, it was possible to charge the discharged portion.

  Furthermore, X-ray diffraction measurement of each sample was then performed.

  Note that SOC is an abbreviation for State of Charge and represents the remaining capacity of the battery. For example, SOC 40% indicates that the remaining capacity is 40% of the total capacity.

For Examples 1 to 3 and Comparative Example 1, the results of the cycle charge / discharge test and X-ray diffraction measurement are as follows:
Fig. 24 Example 1 (gold mesh; 5 cycles) Cycle charge / discharge test Fig. 25 Example 1 (gold mesh; 5 cycles) X-ray diffraction measurement diagram 26 Example 2 (platinum mesh; 5 cycles) Cycle charge / discharge test Fig. 27 Example 2 (platinum mesh; 5 cycles) X-ray diffraction measurement FIG. 28 Comparative example 1 (nickel mesh; 5 cycles) Cycle charge / discharge test FIG. 29 Comparative example 1 (nickel mesh; 5 cycles) X-ray diffraction measurement diagram 30 Example 3 (Carbon coated nickel mesh; 5 cycles) Cycle charge / discharge test Fig. 31 Example 3 (Carbon coated nickel mesh; 5 cycles) X-ray diffraction measurement diagram 32 Example 1 (gold mesh; 10 cycles) Cycle charge / discharge test Fig. 33 Example 1 (gold mesh; 10 cycles) X-ray diffraction measurement FIG. 34 Example 2 (platinum mesh; 10 cycles) Cycle charge / discharge test FIG. 35 Example 2 (platinum mesh; 10 cycles) X-ray diffraction measurement diagram 36 Comparative example 1 (nickel mesh; 10 cycles) Cycle charge / discharge test diagram 37 Comparative example 1 (nickel mesh; 10 cycles) X-ray Diffraction measurement FIG. 38 Example 3 (carbon-coated nickel mesh; 10 cycles) Cycle charge / discharge test FIG. 39 Example 3 (carbon-coated nickel mesh; 10 cycles) Shown in X-ray diffraction measurement.

<1 hour downtime>
Similarly to Experimental Example 1, the positive electrodes for secondary batteries of Examples 1 to 3 and Comparative Example 1 were used as working electrodes, respectively, and a glass cell (secondary battery) was produced in the same manner as in Experimental Example 1.

The following process:
Process I (normal charge / discharge):
(1) Discharge until the end of the plateau of +0.5 to +0.35 V (vs SHE) (2) Charge for 6 hours * (1) and (2) were repeated three times.
Process II (SOC discharge to 40%):
(3) 2-hour discharge process III (SOC 40-60% charge / discharge):
(4) Pause for 1 hour (5) Charge for 50 minutes (6) Pause for 1 hour (7) Discharge for 40 minutes * (4) to (7) were repeated 5 times or 10 times (5 cycles or 10 cycles).
Accordingly, charging and discharging were performed in this order at a current density of 30 mA / g.

  Furthermore, X-ray diffraction measurement of each sample was then performed.

For Examples 1 to 3 and Comparative Example 1, the results of the cycle charge / discharge test and X-ray diffraction measurement are as follows:
FIG. 40 Example 1 (gold mesh; 5 cycles) Cycle charge / discharge test FIG. 41 Example 1 (gold mesh; 5 cycles) X-ray diffraction measurement diagram 42 Example 2 (platinum mesh; 5 cycles) Cycle charge / discharge test diagram 43 Example 2 (platinum mesh; 5 cycles) X-ray diffraction measurement diagram 44 Comparative example 1 (nickel mesh; 5 cycles) Cycle charge / discharge test diagram 45 Comparative example 1 (nickel mesh; 5 cycles) X-ray diffraction measurement diagram 46 Example 3 (carbon coated nickel mesh; 5 cycles) Cycle charge / discharge test FIG. 47 Example 3 (carbon coated nickel mesh; 5 cycles) X-ray diffraction measurement diagram 48 Example 1 (gold mesh; 10 cycles) Cycle charge / discharge test diagram 49 Example 1 (gold mesh; 10 cycles) X-ray diffraction measurement chart 50 Example 2 (platinum mesh; 10 cycles) Cycle charge / discharge test Fig. 51 Example 2 (platinum mesh; 10 cycles) X-ray diffraction measurement diagram 52 Example 3 (carbon-coated nickel mesh; 10 cycles) Cycle charge / discharge test Fig. 53 Example 3 (carbon-coated nickel mesh; 10) Cycle) Shown in X-ray diffraction measurement.

<2 hours downtime>
Similarly to Experimental Example 1, the positive electrodes for secondary batteries of Examples 1 to 3 and Comparative Example 1 were used as working electrodes, respectively, and a glass cell (secondary battery) was produced in the same manner as in Experimental Example 1.

The following process:
Process I (normal charge / discharge):
(1) Discharge until the end of the plateau of +0.5 to +0.35 V (vs SHE) (2) Charge for 6 hours * (1) and (2) were repeated three times.
Process II (SOC discharge to 40%):
(3) 2-hour discharge process III (SOC 40-60% charge / discharge):
(4) Pause for 2 hours (5) Charge for 50 minutes (6) Pause for 2 hours (7) Discharge for 40 minutes * (4) to (7) were repeated 5 times or 10 times (5 cycles or 10 cycles).
Accordingly, charging and discharging were performed in this order at a current density of 30 mA / g.

  Furthermore, X-ray diffraction measurement of each sample was then performed.

For Examples 1 to 3 and Comparative Example 1, the results of the cycle charge / discharge test and X-ray diffraction measurement are as follows:
Fig. 54 Example 1 (gold mesh; 5 cycles) Cycle charge / discharge test Fig. 55 Example 1 (gold mesh; 5 cycles) X-ray diffraction measurement diagram 56 Example 2 (platinum mesh; 5 cycles) Cycle charge / discharge test Fig. 57 Example 2 (platinum mesh; 5 cycles) X-ray diffraction measurement diagram 58 Comparative example 1 (nickel mesh; 5 cycles) Cycle charge / discharge test diagram 59 Comparative example 1 (nickel mesh; 5 cycles) X-ray diffraction measurement diagram 60 Example 3 (Carbon coated nickel mesh; 5 cycles) Cycle charge / discharge test FIG. 61 Example 3 (Carbon coated nickel mesh; 5 cycles) Shown in X-ray diffraction measurement.

  From the above results, when gold mesh, platinum mesh, and carbon-coated nickel mesh were used, no γ-NiOOH was produced even when the rest was sandwiched for 2 hours. On the other hand, when nickel mesh was used, the production of γ-NiOOH was observed by sandwiching the rest for 2 hours. In general, in order to be able to see a peak by X-ray diffraction, a considerable amount (usually 5% or more) is required to be produced, and it is considered that a considerable amount of γ-NiOOH was produced by resting for 2 hours. With the formation of γ-NiOOH, the cycle characteristics deteriorated when nickel mesh was used by sandwiching the rest for 2 hours. However, when gold mesh, platinum mesh and carbon coated nickel mesh were used, the cycle characteristics were reduced. Could be maintained. In particular, when the gold mesh and the carbon coated nickel mesh were used, the cycle characteristics could be maintained more.

The above results are not only applicable to nickel metal hydride batteries using β-NiOOH or Ni (OH) ₂ as the positive electrode active material, but primary batteries or secondary batteries using positive electrode active materials of various batteries. It also applies to.

For example, even when a primary battery is manufactured using MnO ₂ as a positive electrode active material, although not as much as when β-NiOOH or Ni (OH) ₂ is used as a positive electrode active material, a nickel mesh is used as a positive electrode current collector. The capacity and potential could be improved by using a gold mesh. Similarly to the above experimental example, by sandwiching the rest, it was possible to read the change in the crystal structure due to the difference between the nickel mesh, the gold mesh, and the platinum mesh.

Claims (12)

A method of suppressing deterioration due to a local battery reaction in a battery using an electrode for a secondary battery including an electrode active material layer including an electrode current collector and an electrode active material,
Does the electrode current collector comprise at least one selected from the group consisting of a material having an electrode potential higher than -0.75 V compared to the electrode active material and a material that is electrochemically inert to the electrolyte? Alternatively, the surface has at least one layer selected from the group consisting of a substance having an electrode potential higher than −0.75 V compared to the electrode active material and a substance electrochemically inactive with respect to the electrolyte. ,Method. The method according to claim 1, wherein the local battery reaction suppresses generation of a substance that degrades the battery. The method of Claim 1 or 2 which is a method of suppressing degradation by the local battery reaction at the time of an open circuit. The method according to claim 1, wherein the electrode current collector does not contain a material having an electrode potential equal to or lower than −0.75 V compared to the electrode active material on the surface. The electrode current collector is made of a material having an electrode potential higher than −0.75 V compared to the electrode active material, or has an electrode potential higher than −0.75 V compared to the electrode active material. The method in any one of Claims 1-4 which has the layer which consists of substances on the surface. 5. The electrode collector according to claim 1, wherein the electrode current collector is made of a material that is electrochemically inert to the electrolyte, or has a layer made of a material that is electrochemically inert to the electrolyte on the surface. The method of crab. The method according to claim 1, wherein the electrode active material contains at least one selected from the group consisting of nickel hydroxide, β-NiOOH, lead dioxide, and manganese dioxide. The method according to claim 1, wherein the electrode active material contains nickel hydroxide and / or β-NiOOH. The material having an electrode potential higher than −0.75 V compared to the electrode active material contains at least one selected from the group consisting of gold, platinum, silver, iridium and rhodium. The method in any one of -8. The substance that is electrochemically inert to the electrolyte contains at least one selected from the group consisting of a carbonaceous material and a conductive polymer. Method. The method in any one of Claims 1-10 whose said secondary battery is a nickel metal hydride battery, a nickel cadmium battery, a rechargeable alkaline battery, a lithium ion secondary battery, or a lead acid battery. The method according to any one of claims 1 to 11, wherein a new diffraction peak is suppressed from being exhibited at a position of 10.5 to 15 degrees of the diffraction angle 2θ by X-ray diffraction using CuKα rays.

Images