Battery Grid Current Collector

The function of a battery grid is to act as a current collector, which is used to hold the active material and conduct electricity between the active material and the cell terminals. 

In some regions, a widely used lead alloy is lead antimony cadmium. Antimony and cadmium will react to form an intermetallic compound SbCd. During charge, the positive grid undergoes corrosion and produces antimony in the corrosion layer. 

The antimony and cadmium give excellent conductivity through the corrosion layer. Although a small amount of cadmium and antimony is leached from the grid corrosion and deposits on the negative grid, research has indicated that the cadmium is plated over the antimony and raises the potential of the negative plate, which diminishes the water loss. 

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In order for the battery to have an acceptable capacity, the active material is almost always a thick layer of porous, particulate paste and the electronic conductivity of this material is seldom very high. Hence it is necessary to have a current collector, which is usually a metal grid or sheet, to provide a conducting path through the paste and thereby minimize the resistance of the battery. The current collector also acts as a physical support for the active mass which otherwise would be a very brittle structure. 

Another complication had to be matched when the zinc electrode was made reversible in a battery with unstirred electrolyte or an electrolyte gel, dendritic growth of the electrolytically deposited metal takes place. The formation of dendrites cannot be fully suppressed by the use of current collectors with large surface areas (grids, wire fabrics). However, by using improved separators combined in multi layer arrangements, the danger of short-circuiting is reduced. 

There is no question that the development and commercialization of lithium ion batteries in recent years is one of the most important successes of modem electrochemistiy. Recent commercial systems for power sources show high energy density, improved rate capabilities and extended cycle life. The major components in most of the commercial Li-ion batteries are graphite electrodes, LiCo02 cathodes and electrolyte solutions based on mixtures of alkyl carbonate solvents, and LiPF6 as the salt.1 The electrodes for these batteries always have a composite structure that includes a metallic current collector (usually copper or aluminum foil/grid for the anode and cathode, respectively), the active mass comprises micrometric size particles and a polymeric binder. 

The lead/acid battery used in conventional gasoline-fueled automobiles consists of six 2.05 V cells connected in series (for a 12 V electrical system). The current collectors are lead grids filled, when in the charged condition, with powdered lead (anode) and a lead/lead(IV) oxide mixture (cathode), and the electrolyte is aqueous sulfuric acid. During discharge, the following reactions occur ... 

Active mass — The portions of a -> battery or -> accumulator which are participating in electrode reactions, i.e., in the transformation of chemical into electrical -> energy or vice versa. In a -> lead-acid battery active masses are lead dioxide and lead, with the lead or lead alloy grid serving as -> current collector and mechanical holder and all other components are not active masses. For maximum -> energy density the fraction of active mass in the overall cell weight should be as large as possible. 

Current collector — In the battery discipline, a good electron conductor support designed to transfer electrons from the external circuit to the active materials of the cell. Current collectors are usually metal foils or nets that are inert under the operational chemical and electrochemical conditions. In some cases carbon cloth is also used. In secondary - lead-acid batteries the chemical nature of the current collectors (plates, grids) is particularly imperative, as it influences the self-discharge and the performance under overcharge and discharge conditions. Frequently, current collectors have also the important role of imparting mechanical stability to the electrodes. 

Principally the construction of a bipolar battery is not size limited. The plates can be as large as needed with the possibility of any shape desired. Like in fuel cell systems battery plates can be built in m dimensions. This is an important aspect, because regular plate batteries are size limited by the current collector grids like the lead-acid automobil starter battery, which get unproportionally heavy at larger sizes and heavy loads. Generally we can expect energy... 

Lead-battery electrodes can be made as a flat plate with a lead grid as the current collector or as a tubular plate design with a lead rod current collector in the center of tubes. Monopolar electrode current collectors have a conductive lead grid that connects with the terminal. The current collector physically supports the electrode and also collects and carries the current to the electrical system. 

In 2009, Firefly Energy Inc. revealed its Oasis battery, which was developed by Kurt KeUy. This battery is equipped with conventional lead grids as the positive current collector and carbon-graphite foams as the negative current collector. Firefly has named the carbon-graphite technology as 3D technology. Because of the replacement of... 

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