Designing a Reference Electrode – an Approach to Fabricate Laser Perforated Reference Electrodes for Lithium-Ion Batteries

The implementation of reference electrodes (RE) in lithium-ion battery cells represents a promising way to optimize fast-charging, evaluate the C-rate capability of new electrode materials, and monitor cell aging more precisely. However, their design and material choice are under debate. Recently, lithium titanate oxide (LTO, Li 4 Ti 5 O 12 ) and lithium iron oxide (LFP, LiFePO 4 ) have been dip-coated onto wide-meshed metal nets to reduce the blocking effect. Still, this process is elaborate and not common in electrode manufacturing. In this study, we show a new post-processing method to fabricate user-defined REs based on LFP via an ultrashort pulse laser. The REs were designed in such a way that the blocking of the Li + ion pathways should be as small as possible. Testing these special REs in NMC811/graphite full pouch cells revealed slim to no influence on the cell capacity while delivering reproducible voltages, even at high C-rates. Moreover, cell thickness change measurements at the RE site during cycling and post-mortem analysis showed no sign of blocking.