New vehicles with fuel cells readily use hydrogen and oxygen to produce electricity to the motor are optimized and ready to roll on roads. However pure hydrogen storage is not as simple as gasoline. Companies like Hydrogenics and Horizon Fuel cell Technologies have developed technologies to store hydrogen as such as reversible metal hydrides and even the production of the hydrogen by electrolysis, hydrolysis and reforming. However, a fuel cell for portable devices need the source to stored in less space, be safe in operation and weigh less. In this situation, a type of fuel cell was developed that can use methanol directly, this type of models are called as Direct Methanol Fuel Cell, shortly as DMFC. These types of fuel cells are good enough to meet the power output generated by the equivalent Lithium battery.
Now moving one more step a head, in place of methanol, electrolytes like formic acid, provide high power density. Thus the introduction of Direct Formic Acid Fuel Cell (DFAFC) was done into the technology to make fuel cell work efficiently when used for portable devices. Formic acid application influenced further the technology to make fuel cells that can be designed for automobile vehicles.
Two main reaction mechanisms in the DFAFC are;
Platinum-based catalyst totally controls the reaction by;
HCOOH + Pt° → Pt-CO + H2O
Pt°+ H2O →Pt-OH + H+ + e–
Pt-CO + Pt-OH →CO2 + H+e–
- Overall reaction
HCOOH→CO2 + 2H+ + 2e–
Science of electrochemical process provides the requirements and defines the properties of electrode suitable for electrolysis. From scientific data, design of formic acid fuel cell is possible and proven to be effective for portable device fittings. Depending on the physicochemical, mass transfer property of formic acid two factors, found to influence the cost of the fuel cell;
- Anode catalyst
- Electrode structure
Direct liquid formic acid fuel cell dominate ethanol, methanol and hydrogen based fuel cells in terms of storage, fuel availability and high power density. Liquid fuels are easy to handle than gaseous fuels in automobiles and electrical gadget. Direct formic acid fuel cell has high potential to decrease the production prices of consumer products like cell phones, tablets and laptops. Membrane electrode assembly and electrocatalysts has become the future technology to make fuel cell more comfortable for portable devices.
The scientific data shown below is about the effect of formic acid fuel cell temperature on power density for a concentration of three molarity.
|Temperature, oC||Power density, mWcm‑2|
Direct ethanol fuel cell (DEFC): It is also the leading fuel cell model that uses PtSnO2/C and Pt:SnO2 anodic electro catalysts, this cell can withstand and perform well even the acetic acid and acetaldehyde mixture.
Solid fuel cells:
In place of the liquid fuel which make the difficult to built portable device, a solid state electrolyte provides an option. Ball mill reduced the particle size of the material accurate and efficiently. Solid of gadolinium used to make electrolyte by ball milling and by sol gel method it is formed into solid state on ceramic supports. This is a complex arrangement to achieve the operation at low temperature. The solid gadolinium, as the electrolyte particle size effects the efficacy of the solid fuel cell. Even strontium/magnesium doped lanthanum gallate is one of the best solid electrolyte.