The battery - electric device, that converts chemical energy into electrical energy has become a common power source for many industrial and household applications, and is now a multi-billion dollar industry. Lithium iron phosphate batteries are the fastest charging and discharging. The world's largest battery is in Fairbanks, Alaska, composed of Ni-Cd cells. Sodium-sulfur batteries are being used to store wind power.

A storage battery is generally of the wet-cell type. It uses a liquid electrolyte and can be recharged many times. The storage battery consists of several cells connected in series. Each cell contains a number of alternately positive and negative plates separated by the liquid electrolyte. The positive plates of the cell are connected to form the positive electrode; similarly, the negative plates form the negative electrode. In the process of charging, the cell is made to operate in reverse of its discharging operation; i.e., current is forced through the cell in the opposite direction, causing the reverse of the chemical reaction that ordinarily takes place during discharge, so that electrical energy is converted into stored chemical energy. The external devices that supply the appropriate current are called chargers or rechargers.

Rechargeable batteries may be refreshed by charging. In ordinary conditions the recharging is providing by connecting of electrodes of battery to the outer source of electrical currant.

The researchers of Nizhyn Laboratories of Scanning Devices are working to develop a new type of wet battery with internal device – charger, imbedded into the construction of accumulator. This recharger is a capillary pumped electrokinetic nanocell, which periodically renews the chemical composition and structure of substances of electrolyte and of electrodes.

The ordinary well known battery (Fig.1) is made up of connected cells encased in a container and fitted with terminals to provide a source of direct electric current at a given voltage. A cell consists of a positive electrode, a negative electrode and a substance (electrolyte) that acts chemically on the electrodes. The electrolyte functions as an ionic conductor for the transfer of the electrons between the electrodes. Each voltaic cell consists of two half cells connected in series by a conductive electrolyte containing anions and cations. According to Faraday, cations (positively charged ions) are attracted to the cathode, and anions (negatively charged ions) are attracted to the anode. One half-cell includes electrolyte and the electrode to which anions migrate, i.e. the anode or negative electrode; the other half-cell includes electrolyte and the electrode to which cations migrate, i.e. the cathode or positive electrode. In the redox reaction that powers the battery, reduction (addition of electrons) occurs to cations at the cathode, while oxidation (removal of electrons) occurs to anions at the anode.  Many cells use two half-cells with different electrolytes. In that case each half-cell is enclosed in a container, and a separator that is porous to ions but not the bulk of the electrolytes prevents mixing.

The molecular power technologies and among them electrokinetic technologies are the more promising to receive clear sustainable energy in near future  and can be used to recharge wet batteries. Electrokinetic methods and devices for extraction of energy of moving water developed in Nizhyn Laboratories of Scanning Devices and described in the article Surface tension creates current in electrokinetic nanosells (Queltanews.com) are based on the electrokinetic phenomena, arising up in the dispersive systems that are expressed in appearance of difference of potentials in direction of relative motion of phases under action of mechanical forces. The streaming potential is formed by isolated electrolyte, moving through porous body from one isolated Sylphon type chamber into the other under pressure of outer water flux. A source of all these effects - the well known interfacial 'double layer' of charges, which lies in the base of work of wet accumulator (Fig.2).

But another problem exists: Where to find energy to boost electrokinetic’s? In liquids kinetic energy of molecules practically is equal to their potential energy; therefore motion of molecules is complicated. They oscillate around instantaneous equilibrium state which changes in time. But the only thermal oscillating mode of move of liquid molecules around instantaneous equilibrium state do not provides the stable renovation of interfacial double layer of charges and needs of use of moving liquid.

The team of Nizhyn Laboratories of Scanning Devices proposes to use a surface tension for creation of liquid flux.

The energy of surface tension appears in a capillary structure on the boundary of two phases (liquid and solid) as a result of molecular interaction in contiguous tangent phases. The power possibilities of surface layer are explicated by the work, which is necessary to transfer the molecules from the volume phase into a boundary layer. This transfer of molecules goes to the increase of surface energy – creation of surplus of energy of particles within the boundary layer in comparison with their energy in the volume of liquid. The energy of surface tension that appears on the boundary of two phases is transformed into the motion of liquid flux by use of the capillary structure.

With the purpose to increase the effectiveness of capillary structure and to boost the speed of electrolyte lifting through the capillaries the engineers researches very thin (nano)tubes and hope to receive the capillary structures with significantly improved properties. The point is that the character of interaction of molecules of liquid moving in very thin tubes with other molecules of liquid and of material of capillaries walls differs significantly. In limit, when the sizes of capillaries become close to the sizes of molecules of liquid, the surface tension on the boundary of phases increases by factor of 10.

The chart of electrokynetic nanocell and the principle of creation of the electrical double layer (EDL) on the surfaces of a capillary structure sucking the liquid are demonstrated on the Fig.3.

On the Fig.4 the chart of the closed cycle self-sustained surface tension pumped electrokinetic accumulator is shown. This chart uses exclusively the molecular technology for charging and recharging of battery i.e. electrokinetic effect in combination with the motion of liquid in the capillary structures under the action of surface tension. The use of nanotubes makes the process of recharging more productive.

The energy effectiveness and power capability of capillary pumped electrokinetic system may be defined by calculation of work necessary to lift (pump) the appointed mass of electrolyte on the fixed level in a unit of time. 

This closed cycle self-sustained surface tension pumped electrokinetic accumulator has low cost and provides the possibility of the industrial and domestic use in the necessary interval of time, in a necessary amount and in a necessary place. For the increase of an electric power the electrokinetic cells can be grouped in a row of the N elementary cells.

With the use of intrinsic electrokihetic nanocells embedded in a common container the parts of accumulator (electrodes and electrolyte) do not degrade as much when repeatedly charged and recharged. This could lead to smaller, lighter batteries in near future.

New batteries can go out to the market during two years.

By Vasil Sidorov on October 18, 2009 in Queltanews.com

sidorovvasil@gmail.com