Williams Agyei Appiah

University of Agder | UIA · Department of Engineering Science

In-depth analysis of overpotentials in complex electrochemical systems such as lithium-ion batteries is necessary for enhancing their energy and power density. However, dynamic operating conditions and complicated ageing mechanisms create challenges in determining the major sources of these overpotentials. We estimate the over-potentials of cells i...

Due to their high power density and availability, aluminum batteries consisting of graphite positive electrode and ionic liquid electrolytes are promising candidates for post‐lithium‐ion batteries. However, the effect of the various electrode design parameters on their electrochemical performance is not well understood. Herein, a high‐fidelity phys...

Accurate degradation models are crucial to perform efficient battery design and management. The time and resources required to improve the output accuracy of the models depends critically on the ability to assess the sensitivity to the input factors governing the inherent dominant mechanism in the model. Here, we present a sensitivity analysis of a...

Accurate degradation models are crucial to battery design and management. However, the time and resources required to improve the accuracy of the model input factors that the output is sensitive to, which is essential for elucidating the inherent dominant mechanism in the model, remain a challenge. Here we present a sensitivity analysis of a pseudo...

Accurate battery models are important to maximise the utility of batteries which are ubiquitous in modern society from smartphones to electric vehicles. They act as digital twin of batteries and help in expeditious design optimization as well as help us explore interplay of electro- chemical phenomena. Here we present a sensitivity analysis of a ps...

Aluminum sulfur batteries with ionic liquid electrolytes are promising next-generation energy storage devices due to the high abundance of both aluminium and sulfur. However, very little understanding of the discharge mechanism is currently available, which hampers their development. Herein, a mathematical model that considers the complex electroch...

The solid electrolyte interphase (SEI) is a complex passivation layer that forms in situ on many battery electrodes such as lithium‐intercalated graphite or lithium metal anodes. Its essential function is to prevent the electrolyte from continuous electrochemical degradation, while simultaneously allowing ions to pass through, thus constituting an...

Tungsten oxide (WO3) thin films are of critical importance in electrochromic devices as positive electrodes. However, the effect of electrolyte properties on the electrochromic properties of these films is not well ascertained. Herein, we demonstrate the effect of various LiClO4 salt concentrations in propylene carbonate (PC) on the switching speed...

The worldwide energy crisis has drawn the attention of researchers to energy saving, energy-storing, and energy converting devices. Among them, electrochromic devices (ECDs) are being extensively studied to reduce energy consumption. Electrochromism refers to the persistent and reversible change of optical properties by an applied voltage pulse. El...

To enhance delamination limitations in silicon electrode, a thin-film interlayer between silicon electrode and copper current collector is designed using a chemo-mechanical degradation model. The chemo-mechanical degradation model considers the formation of the solid electrolyte interphase on the surface and within the cracks of the silicon electro...

We propose a time‐effective framework for accelerated cyclic aging analysis of lithium ion batteries. The proposed framework involves the coupling of a physico‐chemical capacity‐fade model; that considers the cyclic aging mechanisms of the LiMn2O4/graphite cell, with a physics‐based porous‐composite electrode model to predict cycling performance at...

Treating the surface of current collectors with polydopamine has proven to be a means of resolving the issues related to delamination of silicon composite electrodes (1, 2). This is manifested in the improvement in the electrochemical performance owing to the enhanced adhesion between the silicon composite electrode and current collectors. However,...

We developed a 3D electrochemical model for simulating the electrochemical properties and revealing the internal properties of a single LiFePO4 secondary particle during cycling. The main model parameters, such as the diffusion coefficient and rate constant, were optimized using rate capability data, which have been measured experimentally with a u...

The Cover Feature highlights the use of a physics‐based model to unveil the positive and negative impact of a polydopamine interlayer (brown surface) on the electrochemical performance of silicon‐based lithium‐ion batteries. The polydopamine interlayer enhances the adhesion strength between the silicon composite electrode (blue balls) and copper cu...

To understand the effect of a polydopamine interlayer between a copper current collector and a silicon composite electrode, a physics‐based model is used to analyze the cycle performance of silicon‐based lithium‐ion half‐cells with bare and polydopamine‐treated copper current collectors. We investigate the capacity‐fading mechanisms of the two cell...

The key challenge in all-solid-state batteries is to construct well-developed ionic and electric conductive channels within an all-solid-state electrode, with an extensive contact area between electrode components. Hence, a new design methodology is proposed for all-solid-state electrodes utilizing a 3D geometry interpretation tool and electrochemi...

All-solid-state batteries (ASSBs) are promising secondary batteries which have been studied for high energy density and safety. However, ASSBs have not had excellent electrochemical performance owing to using solid electrolyte instead of liquid electrolyte. Two main reasons are very low ion conduction property due to complex pathway made with the s...

The capacity fading behavior of a LiMn2O4/graphite lithium ion cells at different temperatures is analyzed using a physics-based porous composite electrode model and a parameter estimation technique. The parameter estimation technique is used to extract capacity fade dependent model parameters from experimental cycling data. Although the capacity f...

Lithium-ion batteries (LIBs) have already been adapted for the applications of electric vehicles (EVs) and energy storage systems (ESSs) thanks to their high power density (~1500 W/kg), high energy density (~250 Wh/kg), long cycle life, low self-discharge and among secondary batteries. However, in general, tens of years or thousands of cycles are t...

In recent times, commercially available lithium ion batteries (LIBs) employ graphite, with a theoretical capacity of 372 mAh g ⁻¹ , as their anode material. To enhance the energy density of LIBs, alternative anode materials with higher capacities, such as Li metal, Si, and various alloys, have been extensively exploited. With its advantages of a hi...

A coupled chemo-mechanical model which considers the contact resistance as well as the influence of the attractive forces inside the contact area between the electrode and current collector was developed to evaluate the effects of the adhesive strength of a binding material on the electrochemical performance of silicon-based lithium-ion batteries....

Lithium-ion batteries (LiBs) have already become main energy storage devices for a variety of applications such as cellular phones, laptops, electric vehicles (EVs), and energy storage systems (ESSs). Because they have not only high energy density but also long cycle life performance with low self-discharging behaviour. Furthermore, the market size...

To overcome the limitation of simple empirical cycle life models based on only equivalent circuits, we attempt to couple a conventional empirical capacity loss model with Newman's porous composite electrode model, which contains both electrochemical reaction kinetics and material/charge balances. In addition, an electrolyte depletion function is ne...

To investigate the effects of the exposure of battery tabs to humidity on the self-discharge properties of full-cell type lithium-ion batteries (LIBs), we assembled two different types of LIBs, composed of NCM/graphite or LCO/graphite, and compared their discharge retention abilities after storage in humid conditions (90% relative humidity (RH)) wi...

A mathematical model is developed for the cyclic aging of a spinel LiMn2O4/graphite lithium-ion cell in this study. The proposed model assumes the formation and dissolution of the solid electrolyte interphase (SEI) in the anode, Mn(II) dissolution of the LiMn2O4 cathode active material due to the Mn(III) disproportionation reaction, the effect of d...

To enhance the understanding of capacity fade mechanism in lithium ion batteries consisting of a spinel-based cathode and an artificial graphite, an all-inclusive mathematical model describing the cycling performance of LiMn 2 O 4 /graphite lithium ion cell is developed in this work. The proposed model assumes the formation and dissolution of the s...

The application of lithium ion batteries (LIBs) have been widen from IT devices to electric vehicles (EVs). To be precise, EVs adopting LIBs are being increased because LIBs guarantee high energy density and cycle life. LIBs are also sensitive to external environmental factors such as temperature, humidity, vibration, etc. In order words, these con...

To accomplish higher mileage targets of electric vehicles (EVs), lithium/air or lithium/sulfur batteries using lithium metal as an anode have attracted much attention owing to their high energy density. However, lithium metal has a major drawback, the so-called lithium dendrite which results in inhibited battery performance and instability. Hence,...

As the size of lithium-ion batteries (LIBs) becomes larger, it is also time consuming and expensive to get lots of electrochemical properties experimentally. In particular, it needs more resources to optimize all cases for designing and developing the right large format cell for a given application. Hence, we adopt a previously designed pseudo two...

Lithium metal having the lowest reduction potential (-3.04 V vs. SHE) and high specific capacity (~3800 mAh g ⁻¹ ) have not been successfully implemented in commercial lithium secondary batteries (LSBs) due to the formation of lithium dendrite, resulting in inhibited battery performance and instability. However, to accomplish the mileage and high e...

Li metal has been considered as an anode material for lithium secondary batteries (LSBs) for over four decades. However, its uncontrolled chemical reactivity towards organic solvents and dendritic growth at random in electrochemical cells delayed its commercialization in the secondary battery market. Thus, without developing stable Li metal electro...

Li-ion batteries (LIBs) as an energy storage device have been established as a leading and a promising candidate for automotive and aerospace applications. But to meet the various application requirements, the energy and power density of LIBs need to be optimized for a given electrode material by controlling its porosity and thickness. Changes in e...

ESS (Energy Storage System). ESS ,. , ESS ,. , ESS , (DC-IR). , HPPC (Hybrid Pulse Power Characteristics) J-Pulse (JEVS D 713, Japan Electric Vehicle Association Standards). Energy storage systems (ESSs) have been utilized widely in the world to optimize the power operation system and to improve the power quality. As lithium secondary batteries are...

Most of the separators currently used in lithium-ion batteries (LIBs) are based on microporous polyolefin membranes such as polyethylene (PE) and polypropylene (PP). Such separators have excellent mechanical strength and chemical stability, but their thermal properties should be further improved to meet required level of safety for large-format LIB...

Most of the separators currently used in lithium-ion batteries (LIBs) are based on microporous polyolefin membranes such as polyethylene (PE) and polypropylene (PP). Such separators have excellent mechanical strength and chemical stability, but their thermal properties should be further improved to meet required level of safety for large-format LIB...

It is important to understand the electrochemical performance as well as the influence of various cathode materials; LiMn2O4 and Li[Ni0.6Co0.2Mn0.2]O2, on each other when mixed together as a single positive electrode for lithium ion batteries. In view of this, we used a previously developed lithium ion mathematical model for treating multiple activ...

It is important to understand the electrochemical performance as well as the influence of various cathode materials; LiMn 2 O 4 and Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 , on each other when mixed together as a single positive electrode for lithium ion batteries. In view of this, we used a previously developed lithium ion mathematical model for treating mul...

The adhesion strength of lithium-ion battery (LIB) electrodes consisting of active material, nano-sized electric conductor and polymeric binder is measured by a new analysis tool, called the Surface and Interfacial Cutting Analysis System (SAICAS ® ). Compared to the conventional peel test with the same electrode, SAICAS ® gives higher adhesion str...