3D electrode architectures for high energy and high power lithium-ion batteries

Abstract

There is worldwide a strong effort to increase energy and power density on battery level for future electric vehicles. In addition, the demand for cost efficient, reliable, and long lifetime lithium-ion batteries (LIB) is continuous increasing. For the development of next-generation LIB a new scientific-technical approach was established by merging the 3D battery concept with high mass-loaded electrodes. The 3D battery concept is realized by laser structuring of electrodes and has a huge impact on high rate capability and lifetime of lithium-ion batteries. In frame of process up-scaling, ultrafast laser ablation including roll-to-roll processing was established for thick film electrodes without damaging the active material. Post-mortem studies using laser-induced breakdown spectroscopy were carried out to study degradation processes and to illustrate the formation of new lithium diffusion pathways in 3D electrodes. The studies were performed with lithium nickel manganese cobalt oxide as cathode and graphite/silicon as anode. Silicon has the benefit to provide one order of magnitude higher gravimetric energy density than the common used graphite. However, a bottleneck of silicon is its huge volume change of 300% during electrochemical cycling. High mechanical tension may arise, which results in crack formation, continuous formation of solid electrolyte interphase, and subsequent electrode delamination. It was shown that batteries with laser structured electrodes benefit from a homogenous lithiation and delithiation, reduced compressive stress, and overall improved electrochemical properties in comparison to batteries with unstructured electrodes. A new manufacturing tool is presented for next-generation battery production to overcome current limitations in electrode design and cell performance.