The performance of lithium-ion batteries is determined by the architecture and properties of electrodes formed during manufacturing, particularly in the drying process when solvent is removed and the electrode structure is formed. Temperature is one of the most dominant parameters that influences the process, and therefore a comparison of temperature effects on both NMC622-based cathodes (PVDF-based binder) and graphite-based anodes (water-based binder) dried at RT, 60, 80, 100 and 120 °C has been undertaken. X-ray computed tomography showed that NMC622 particles concentrated at the surface of the cathode coating except when dried at 60 °C. However, anodes showed similar graphite distributions at all temperatures. The discharge capacities for the cathodes dried at 60, 80, 100 and 120 °C displayed the following trend: 60 °C < 80 °C < 100 °C < 120 °C as C-rate was increased which was consistent with the trends found in adhesion testing between 60 and 120 °C. Focused-ion beam scanning electrode microscopy and energy-dispersive X-ray spectroscopy suggested that the F-rich binder distribution was largely insensitive to temperature for cathodes. In contrast, conductivity enhancing fine carbon agglomerated on the upper surface of the active NMC particles in the cathode as temperature increased. The cathode dried at RT had the highest adhesion force of 0.015 N mm⁻¹ and the best electrochemical rate performance. Conversely, drying temperature had no significant effect on the electrochemical performance of the anode, which was consistent with only a relatively small change in the adhesion, related to the use of lower adhesion water-based binders.

Lithium-ion battery (LIB) performance can be significantly affected by the nature of the complex electrode microstructure. The carbon binder domain (CBD) present in almost all LIB electrodes is used to enhance mechanical stability and facilitate electronic conduction, and understanding the CBD phase microstructure and how it affects the complex coupled transport processes is crucial to LIB performance optimization. In this work, the influence of microporosity in the CBD phase has been studied in detail for the first time, enabling insight into the relationships between the CBD microstructure and the battery performance. To investigate the effect of the CBD pore size distributions, a random field method is used to generate in silico a multiple-phase electrode structure, including bimodal pore size distributions seen in practice and microporous CBD with a tunable pore size and variable transport properties. The distribution of macropores and the microporous CBD phase substantially affected simulated battery performance, where battery specific capacity improved as the microporosity of the CBD phase increased.

Bilayer cathodes comprising two active materials are explored for their ability to improve lithium-ion battery charging performance. Electrodes are manufactured with various arrangements of lithium nickel manganese cobalt oxide Li[Ni_0.6Co_0.2Mn_0.2]O₂ (NMC622) and lithium iron phosphate LiFePO₄ (LFP) active particles, including in two different discrete sub-layers. We present experimental data on the sensitivity of the electrode C rate performance to the electrode design. To understand the complex bilayer electrode performance, and to identify an optimal design for fast charging, we develop an extension to the Doyle-Fuller-Newman (DFN) model of electrode dynamics that accommodates different active materials in any number of sub-layers, termed the multilayer DFN (M-DFN) model. The M-DFN model is validated against experimental data and then used to explain the performance differences between the electrode arrangements. We show how the different open circuit potential functions of NMC and LFP can be exploited synergistically through electrode design. Manipulating the Li electrolyte concentration increases achievable capacity. Finally the M-DFN model is used to further optimize the best performing bilayer electrode arrangement by adjusting the ratio of the LFP and NMC sub-layer thickness.

In this work, we systematically studied the effect of porous structural properties on performance of the micro-mesoporous graphene_1−x(MoS₂)_xas anodes in lithium-ion and sodium-ion batteries.

Lithium-ion batteries (LIB) are synonymous with the modern age of electrification, yet advances in battery design, manufacturing, and chemistry are still urgently needed. Mathematical modelling plays an important role in understanding LIB performance and can provide physics informed design directions, optimisation and explain outcomes. We present an exploration and detailed comparison of the commonly used homogenised Doyle-Fuller Newman (DFN) model and X-ray computed tomography (CT) based microstructural model for LIBs, along with experimental data. We provide insights into the relative benefits of each model and highlight why they are important to battery technology development. We compare two common cathode chemistries, lithium nickel manganese cobalt oxide (NMC), and lithium iron phosphate (LFP), and investigate discharge current density. The DFN and CT-based models show good agreement for averaged LIB metrics, such as the voltage response and active material utilization, demonstrating that homogenised, computationally inexpensive models are an essential basis for battery design and optimisation. The CT-based microstructural model provides further insight into localised particle and electrode dynamics, considering heterogeneities that are a source of battery degradation. Qualitatively, the models also compare well with experimental secondary ion mass spectrometry mapping of the Li concentration in the active particles across the electrode thickness.

A porous, spray-deposited Al₂O₃-based separator was developed to enable the direct deposition of an electrode/separator/electrode Li-ion battery full cell assembly in a single operation. The optimized sprayed separator consisted of 50 nm Al₂O₃ particles, 1 wt % poly(acrylic acid), and 5 wt % styrene-butadiene rubber, deposited from an 80:20 vol % suspension of water and isopropanol. Separators between 5 and 22 μm thick had consistent and similar porosity of ∼58%, excellent wettability, thermal stability to at least 180 °C, adequate electrochemical stability and high effective ionic conductivity of ∼1 mS cm^-1 at room temperature in an EC/DMC electrolyte, roughly double that of a conventional polypropylene separator. A sequentially deposited three-layer LiFePO₄/Al₂O₃/Li₄Ti₅O₁₂ full cell, the first of its kind, showed similar rate performance to an identical cell with a conventional polypropylene separator, with a capacity of ∼50 mAh g^-1 at 30 C. However, after cycling at 2 C for 400 cycles, Al₂O₃ separator full cells retained 96.3% capacity, significantly more than conventional full cells with a capacity of 79.2% remaining.