Improving the Fast Charging Capability of Lithium-Ion Battery Graphite Anodes by Implementing an Alternative Binder System

Abstract

An alternative binder system for water-processed graphite anodes for lithium-ion batteries was developed and electrochemically investigated in terms of fast charging capability. The conventionally used binder system for anode coatings, based on CMC and SBR, shows good rheological and mechanical properties, but is limited in its electrochemical performance with respect to high charging currents. However, a marked improvement in fast charging capability is necessary to accelerate the market share of battery electric vehicles. Therefore, we systematically developed an alternative, water-based binder system to improve the fast charging capability of graphite anodes. Thereby, the most promising alternative binder system consisting of alginate, PEO and PVP (2:1:1) showed an improvement in charging performance at 4 C (10 mA cm−2) in the CC-step by more than 150% in 2.5 mAh cm−2 research pouch cells, compared to the reference binder system consisting of CMC and SBR (1:1). The improvement in fast charging capability could be assigned to a reduced ionic pore resistance, as well as a larger active surface area, whereas the pore size distribution, the total surface area, as well as the wettability of the electrode, influence the active surface area. Furthermore, the alternative binder system reveals an improved cycling stability beyond 1,500 cycles.