Abstract:
Lead-acid batteries with conventional materials are now no longer able to meet the
emerging requirements for several applications in telecom, automobile, solar, etc., Due to
the increase in the demand for higher performances, batteries keeping with the change in
the CO2 emissions, carbon-based materials, which are of possible consideration, are
investigated to meet the requirements. The areas in which the lead acid battery is more
affect are is the sulphate growth or the grid growth of the current collectors and sulphation
in the negative electrode.
Several types of carbon with low and higher dimensions have been attempted to study the
electrical performances in the negative plates of lead-acid batteries (LAB). Attempts were
made to improve discharge capacity, charge acceptance & life cycling ability of the LAB. Out
of many types (2D) Graphene has been selected to evaluate the performance of the LAB due
to its unique characteristics. The Carbon Black was commercially purchased as the
negative active material additive for the performance comparison, and graphene has been
synthesized in our laboratory.
Production of Graphene in Bulk form through chemical methods is a significant drawback
of graphene-related research, which is hindering its commercialization. In this work, various chemical methods for the synthesis of graphene were examined, like the Hummers
method, Modified Hummers method, and Microwave-assisted acid method. The results were
very accurate by the microwave-assisted acid method. The productivity and purity of the
produced graphene using this method are very high. The Morphology, Structure, and Phase
characteristics were well studied by using various characterization techniques like XRD,
SEM/EDS, Raman, and BET.
Along with Graphene layers, which were synthesized by microwave-assisted method, the
commercially purchased carbon black was also used as part of the electrode material validation for energy applications. The carbon-based nanomaterial is used as an additive for
negative electrode material for absorbed Glass Mat (AGM) lead-acid batteries.
For making an electrode for lead acid battery application, electrochemical & electrical
studies are essential to rationalize.
In one aspect, to address the premature failure (PMF) due to the grid surface, the graphene
material is prepared in the colloidal for and applied to the grids. A 2V cells was assembled
to study the coated grid performance and found the positive coated grid has better electrical
behavior than the negative coated grids. This higher-rated capacity is prepared with positive
coated grids (2V-600Ah). The electrical tests at lower rates 0.1C, 0.5C, and 1C are
marginally higher than the uncoated grids. But at higher current discharges for shorter
durations like C15 minutes and C5 minutes, the positive coated grids outperformed by 2 to
3 times, respectively.
In another aspect, Graphene was prepared and applied in negative active material of AGM
lead acid battery, and studies were carried out. Other individual components of the
composite like BaSO4 & Lignin are used to integrate the low dimensional carbon as an
additive composite and are dry mixed with the active material (Lead Oxide) and applied to
the lead grid used as current collectors.
By the experimental investigation as per Japanese Industrial Standards (JIS) the electrical
performances, it is observed that the current discharge capacity increased by nearly 27%
with graphene as an additive in NAM.
Whereas in charge acceptance capability enhancement of 14% is observed, and the time
taken for discharge capacity of the batteries with Graphene has exceeded the requirement
and for a long-time-interval of 23%, respectively.
The cycle life of the graphene batteries increased by 33% compared to that of the control
batteries above the 40%SoH condition.
The results demonstrated that the component particles are uniformly distributed towards
the nanomaterials; this tells the proper formation of the composite. Electrochemical studies of graphene nanomaterial electrode reveal that the impedance characteristic is very
different from that of traditional one. Therefore, the electrical performances are evidence of
these materials having the ability of electrode material properties for energy applications.
