Highly corrosion-resistant porous metal body and method for producing the same

Abstract

Provided are a porous metal body that is excellent in terms of corrosion resistance and that is suitable for a collector for batteries such as lithium-ion batteries, capacitors, or fuel cells; and methods for producing the porous metal body. A production method includes a step of coating a porous nickel body with an alloy containing at least nickel and tungsten or a metal containing at least tin; and a subsequent step of a heat treatment. Another production method includes a step of forming a nickel-plated layer on a porous base and then continuously forming an alloy-plated layer containing at least nickel and tungsten or tin, a step of removing the porous base, and a step of reducing metal. Such a method can provide a porous metal body in which tungsten or tin is diffused in a porous nickel body or a nickel-plated layer.

Description

TECHNICAL FIELD[0001]The present invention relates to a porous metal body used for a collector for batteries such as lithium-ion batteries, capacitors, or fuel cells.BACKGROUND ART[0002]In general, metal foils such as aluminum foils are used, in lithium-ion batteries, as collectors (supports) to which positive-electrode materials and negative-electrode materials are made to adhere. However, metal foils have a two-dimensional structure and hence are inferior in terms of carrying of active materials and packing density of active materials to porous bodies. Specifically, metal foils cannot hold active materials in a manner in which metal foils contain active materials. Accordingly, metal foils cannot suppress expansion or contraction of active materials and hence the amount of active materials held on metal foils is made small to ensure a life for a certain period. In addition, the distance between collectors and active materials is long and hence active materials away from collectors ...

AI Technical Summary

Benefits of technology

The present invention provides a porous metal body with high strength and resistance to corrosion, which is suitable for use in batteries and fuel cells. By subjecting a porous nickel body to a plating treatment with nickel-tungsten or tin, the body's stress is reduced, resulting in a stable layer with enhanced quality. Additionally, a continuous plating process improves adhesion between the plated layers, reducing separation and cracks due to stress.

Problems solved by technology

However, metal foils have a two-dimensional structure and hence are inferior in terms of carrying of active materials and packing density of active materials to porous bodies.

Specifically, metal foils cannot hold active materials in a manner in which metal foils contain active materials.

In addition, the distance between collectors and active materials is long and hence active materials away from collectors are less likely to be used.

Thus, the capacity density becomes low.

However, these also substantially have two-dimensional structures and hence a considerable increase in the capacity density cannot be expected.

In particular, since positive-electrode collectors are susceptible to oxidation by electrolytes under a high charging-discharging voltage, positive-electrode collectors having sufficiently high oxidation resistance and electrolytic resistance have also been demanded.

However, positive-electrode collectors that have oxidation resistance and electrolytic resistance, have a high porosity, and are suitable for industrial production, are not provided for lithium nonaqueous-electrolyte secondary batteries for the following reasons.

However, porous nickel bodies are susceptible to oxidation in lithium nonaqueous-electrolyte secondary batteries and dissolved in electrolytic solutions.

Accordingly, such batteries are not able to be sufficiently charged after charging and discharging are performed for a long period of time.

Accordingly, organic-resin bodies cannot be plated and it is difficult to plate organic-resin surfaces.

Thus, porous aluminum collectors are not currently provided.

However, for the same reason as for aluminum, it is also difficult to provide collectors having a high porosity by plating organic-resin surfaces with stainless steel.

However, stainless-steel powder is very expensive.

In addition, a porous organic-resin body to which the powder adheres is removed by incineration and the resultant body has a poor strength and is not usable, which is problematic.

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