The market for batteries is rapidly growing, and the increased demand for portable electronic devices, including mobile phones and laptops requires greater advances in battery technology in order to provide a light weight, long lasting and stable power source. Battery technology is also being pushed further in electric vehicle applications, which require even more lightweight, high power and fast charging batteries.
Batteries are electrochemical cells, with chemical reactions at the electrodes consuming and releasing the electrons that power a circuit. Batteries can be classed as either primary (disposable) or secondary (rechargeable) and use a wide range of materials in order to achieve the required energy density at a reasonable cost.
An important aspect in the design of the battery material is the particle size, particle size distribution and particle shape of the materials used within the electrodes. Small particle size electrodes increase the rate of electrochemical reactions due to their larger surface area, which is favorable in terms of power production. Energy storage capacity and electrolyte mobility on the other hand is related to porosity, which is influenced by particle size and particle shape distribution, with larger particle sizes generally favored. Using a mixture of coarse and fine battery materials is one way to meet the conflicting requirements for power and storage capacity, and is common practice.
For Lithium-ion batteries the micro-porosity and crystallinity of the graphite electrodes is also critical since this determines the amount of Lithium ions that can be accommodated within the structure during charging (capacity) and their charge/discharge rate.
The primary route for electrode manufacture is to apply a slurry of electrode material onto a metal foil. The slurry is composed of electrode particles (anode or cathode) and binder material (solvent and polymer). The rheology of the slurry is important for determining the stability of the slurry, how easily it can be applied, and the resulting film properties including thickness and density which influence ion transfer rate and recharge cycle time of the battery. Another major factor influencing stability of electrode dispersions is zeta potential, which must be optimized to prevent particle aggregation.
Malvern Instrument’s range of analytical products and expertise can assist the Battery sector by helping to:
- Optimize electrode particle size and particle shape of battery materials to give the desired power and storage capacity
- Characterize the crystallinity of graphite electrodes for use in Li-ion batteries using Raman spectroscopy
- Optimize slurry rheology to give required stability, flow properties and film characteristics
- Enhance stability of electrode dispersions by measuring and controlling zeta potential of Batteries.