Optimization of the Electrode Properties for High-Performance Ni-Rich Li-Ion Batteries

Abstract

The microstructure of the electrodes in lithium-ion batteries (LIBs) strongly affects their gravimetric and volumetric energy and power as well as their cycle life. Especially, the effect of the microstructure in the case of next-generation Ni-rich cathode materials has not yet been investigated. A comprehensive understanding of the calendering process is therefore necessary to find an optimal level of the electrode microstructure that can enhance lithium-ion transportation, minimize plastic deformation, and improve conductivity. This work therefore aims to investigate the effect of microstructure and wettability on the electrode kinetics of next-generation Ni-rich LiNi0.88Co0.09Al0.03O2-based 18650 cylindrical cells, which were produced at the semiautomation scale of the pilot plant. Thus, all materials, electrodes, and the battery production are in quality control as the same level of commercial LIBs. With the optimized microstructure and other properties including a finely tuned compaction degree of 17.54%, a thickness of 188 μm, a sheet resistivity of 36.47 mΩ cm–2, a crystallite size of 88.85 nm, a porosity of 26.03%, an electrode Brunauer–Emmett–Teller (BET) surface area of 1.090 m2 g–1, an electrode density of 2.529 g cm–3, and an electrolyte uptake capability of 47.8%, the optimized LiNi0.88Co0.09Al0.03O2 18650 cylindrical cells exhibit excellent high-rate capacity retention, fast Li-ion diffusion, and low internal resistance. The optimized electrode microstructure of next-generation Ni-rich cathode materials could be an effective strategy toward the real application of next-generation Ni-rich LIBs.

Multilayer Graphene as a Cathode Conductive Additive in Lithium-Ion Pouch Cells: A Correlation of Changes in Electrolyte Uptake and Composition of the Electrode Electrolyte Interface with Enhanced Cycling Stability

“…The change in the peak intensity in d Q /d V is more in NMC-CB-MLG-G at 3.5 and 3.7 V. The quantity of electrolyte added and soaking time for the electrode wetting are the same in both cells. The % electrolyte uptake is calculated by following the ref . The % electrolyte uptake (EU) is more in NMC-CB-MLG electrode (26%) than NMC-CB electrode (21%).…”

“…CAs will also influence tortuosity and electrolyte uptake, in addition to the e – and Li + transport. A better understanding of these effects can be investigated by multilayer pouch cells. , However, only a few studies explored the usage of alternative CAs in the pouch cell format. Fang et al tested graphene as a CA using a prototype pouch cell with an estimated capacity of 10 Ah .…”

Insights into Influencing Electrode Calendering on the Battery Performance

“…[193] Compaction of the cathodes via calendering can improve the electronic percolation network and volumetric energy density, however, for NCA, over-compaction can destroy the mechanical properties, facilitate particle cracking and restrict electrolyte wetting. [193] It is vital to optimize the calendering approach for this material. Lu et al [194] investigated the impact of calendering on LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathodes, prepared with Gr, CB and PVDF, with varying thicknesses and demonstrated that improved coating uniformity could be achieved after calendering.…”

“…[ 192 ] However, Ni‐rich cathodes can be subject to extreme capacity fading owing to CAM particle cracking and breakage during long‐term cycling. [ 193 ] Compaction of the cathodes via calendering can improve the electronic percolation network and volumetric energy density, however, for NCA, over‐compaction can destroy the mechanical properties, facilitate particle cracking and restrict electrolyte wetting. [ 193 ] It is vital to optimize the calendering approach for this material.…”

“…It was demonstrated that stronger compaction partially suppresses the phase separation of NCA and causes partial destruction of the NCA agglomerates, which improves the ion transport characteristics. A study by Sarawutanukul et al [ 193 ] on LiNi 0.88 Co 0.09 Al 0.03 O 2 (NCA) employed calendering processes to optimize the electrode properties. They observed a decrease in NCA crystallite size after calendering, which can contribute to an accumulation of strain on the particle and decrease the capacity retention capabilities.…”