In recent years, there has been a growing demand for lithium-ion (Li-ion) batteries that have a longer lifetime and provide more consistent performance in harsh environment applications such as those found in the automotive, defence and oil exploration systems sectors.
Currently, in extreme atmospheric conditions, the expansion and contraction that the cell experiences cause a binder depletion between its current collector and its coated layer which results in delamination between the copper foil and its coated graphite, therefore causing significant reliability issues.
The challenge for the MTC was to exploit recent advancements in the laser processing of battery materials including the use of short, pulsed lasers to optimise Li-ion battery performance. The aim was to introduce different properties and restructure the surfaces inside Li-ion batteries to improve surface adhesion between the coated layer and the anode to ultimately reduce the possibility of failure.
To address the challenge set out, engineers at the MTC utilised laser surface micro-texturing, a new, innovative process using ultra short, fast lasers that could achieve the desired performance benefits in the proof-of-concept demonstrator.
Firstly, the team completed a period of analysis on an off-the-shelf Li-ion battery to understand where the loss of performance was occurring and how this could be addressed.
Using laser surface micro-texturing, the team were able to create well defined and controlled structures on the surface of the anode to increase adhesion and improve bond strength which in doing so would better the quality of manufacturing in this high-energy anode material.
Through a series of further in-house tests to prove the validity of the solution, additional optimisations on the restructured surfaces were completed to enhance and prove the performance of the demonstrator battery in testing environments.
The MTC used laser surface micro-texturing and an optimised laser setting to produce a new, micro-textured demonstrator battery that performs better under extreme conditions. The optimised battery showed a 32% improvement in the surface adhesion leading to a more robust and safer cell compared to the off-theshelf Li-ion battery.
As a result of this project, the MTC has identified a high value manufacturing process that is a viable and scalable, alternative method to the current ‘Roll-to-Roll’ manufacturing process of the cells.
Through utilising an advanced laser-based surface engineering process, alongside the expertise of experienced researchers and engineers, the MTC has successfully demonstrated the positive impact that lasers can have on the performance of battery cells in extreme environments.
The integration of laser surface micro-texturing on the production line could also save time and make a vital performance change leading to the removal of calendaring from the current process and the use of more powerful lasers as surface texturing technology matures, improving the overall quality of Li-ion battery manufacturing.
Further to this, the MTC identified that this innovative process could be used to lengthen the life span of the battery and enhance how the cell manages heat by focusing on the texturing of the battery housing to allow the cell to charge under higher currents.
The project has also shown that laser surface microtexturing could provide wider benefits to other high value manufacturing industries. This process to improve the bond strength of adhesives could boost heat conduction in sectors where high-performance, thermal management units are used such as the aerospace, automotive and defence arenas. It could also support anti-fouling systems on propellors in the marine sector by creating surfaces with well-defined structures that are better for the environment and reduce pollution.
Overall, the creation of this new Li-ion battery demonstrator has shown that laser-based engineering processes could be vital to the development of Li-ion battery cells, and it has provided the MTC with an opportunity to work with its membership to explore how lasers could further influence UK manufacturing.