Eric Logan

Dalhousie University | Dal · Department of Physics and Atmospheric Science

LFP/Graphite cells are attractive because they are cheaper [1] , safer [2,3] and can achieve acceptable energy density for most applications. A limitation of the LFP/Graphite cells is their inferior capacity retention at elevated temperature when compared to NMC/Graphite cells especially in the absence of electrolyte additives, e.g., VC (Vinylene c...

In an effort to better understand capacity loss mechanisms in LiFePO4 (LFP)/graphite cells, this work considers carbon-coated LFP materials with different surface area and particle size. Cycling tests at room temperature (20°C) and elevated temperatures show more severe capacity fade in cells with lower surface area LFP material. Measurements of Fe...

The use of LiPF6 in Li-ion battery electrolytes provides sufficient stability, conductivity, and cost in most applications. However, LiPF6 has also been known to cause degradation in Li-ion cells, primarily from its thermal decomposition or hydrolysis to form acidic species. This work considers the use of imide salts lithium bis(fluorosulfonyl)imid...

Single crystal Li[Ni0.5Mn0.3CoO.2]O2//graphite (NMC532) pouch cells with only sufficient graphite for operation to 3.80 V (rather than ≥4.2 V) were cycled up to either 3.65 or 3.80 V to facilitate comparison with LiFePO4//graphite (LFP) pouch cells on the grounds of similar maximum charging potential and similar negative electrode utilization. The...

The charge-discharge cycling performance of pouch cells with single crystal LiNi0.5Mn0.3Co0.2O2 (SC532), LiNi0.8Mn0.1Co0.1O2 (SC811) and a prototype polycrystalline Co-free core-shell material with an average 94% Ni content (Ni94) were compared in this work. Two upper cut-off voltages (UCVs) per cell type were chosen to either include or exclude th...

Unwanted redox shuttles can lead to self-discharge and inefficiency in lithium-ion cells. This study investigates the generation of a redox shuttle in LFP/graphite and NMC811/graphite pouch cells with common alkyl carbonate electrolyte. Visual inspection of the electrolyte extracted after formation at temperatures between 25 and 70°C reveals strong...

Part II of this 2-part series examines the impact of various graphite materials on NMC811 pouch cell performance using Ultra-High Precision Coulometry (UHPC), isothermal microcalorimetry, and in-situ stack growth. A simple lifetime projection of the best NMC811/graphite cells as a function of operating temperature is made. We show that graphite cho...

Isothermal microcalorimetry has previously been used to probe parasitic reactions in Li-ion batteries, primarily studying Li[NixMnyCo1-x-y]O2 (NMC) positive electrode materials. Here, isothermal microcalorimetry techniques are adopted to study parasitic reactions in LiFePO4 (LFP)/graphite cells. Features in the heat flow from graphite staging trans...

A few weight percent of electrolyte additives can dramatically improve Li-ion battery performance and lifetime. A systematic investigation of a series of electrolyte additive formulations was performed on bimodal (BM) and single crystal (SC) LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811)/artificial graphite (AG) pouch cells. Long-term cycling tests at differe...

Anode-free Li metal cells are one of the most appealing energy storage technologies beyond Li-ion batteries due to their superior theoretical specific and volumetric energy densities. However, long cycle life in an anode-free cell remains elusive due to difficulties reversibly plating and stripping metallic lithium. Isothermal microcalorimetry was...

State-of-the-art Li-ion batteries (LIBs) typically consist of a graphite anode with a capacity of 372 mAh g ⁻¹ and a cathode material consisting of a layered transition metal oxide in the form of LiMO 2 , where M = Ni, Mn, Co or Al (NMC and NCA material), or olivine-type material in the form of LMPO 4 , where M = Fe, such as LiFePO 4 (LFP). Propose...

Lithium iron phosphate (LiFePO4, or LFP) is a widely used cathode material in Li-ion cells due to its improved safety and low cost relative to other materials such as LiNixMnyCozO2 (x + y + z = 1, NMC). To improve the calendar life of LFP cells, an investigation of their failure mechanisms is necessary. Herein, we use scanning micro X-ray fluoresce...

LiFePO4 (LFP) is an appealing cathode material for Li-ion batteries. Its superior safety and lack of expensive transition metals make LFP attractive even with the commercialization of higher specific capacity materials. In this work the performance of LFP/graphite cells is tested at various temperatures and cycling protocols. The amount of water co...

Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 /graphite pouch cells were cycled using protocols that included 24 h spent at high voltage (≥ 4.3 V) under constant voltage or open circuit conditions to accelerate failure. Compared to traditional cycling, failure was reached up to 3.5 times faster. When this protocol was applied to cells containing low LiPF 6 concentr...

Monitoring the dynamic chemical and thermal state of a cell during operation is crucial to making meaningful advancements in battery technology as safety and reliability cannot be compromised. Here we demonstrate the feasibility of incorporating optical fibre Bragg grating sensors into commercial 18650 cells. By adjusting fibre morphologies, wavele...

Electrolyte systems based on binary mixtures of organic carbonate ester co-solvents have limitations in ionic transport and thus limit extreme fast charge (XFC) and high-rate cycling of energy dense lithium-ion cells with thick electrodes (> 80 micrometers per side) at ambient temperature and below. Here, we present LiPF6 in methyl acetate (MA) as...

Ni-rich positive electrode materials for Li-ion batteries have the dual benefit of achieving high energy density while reducing the amount of Co used in cells. However, limitations in cycle life are still an issue for the widespread adoption of these materials. The benefit of using single crystal materials has been demonstrated for LiNi0.5Mn0.3Co0....

Li-ion batteries with fast charging capabilities will push the adoption of electric vehicles (EVs). The United States Department of Energy has stated goals of achieving “Extreme Fast Charging” (XFC) – charging to 80% capacity in 15 minutes or under – by 2028. The liquid electrolyte plays an extremely important role in achieving this goal. This revi...

In the pursuit of surpassing the energy density of conventional lithium ion cells, significant efforts have been made to develop lithium metal cells. However, many reports in the literature utilize Li-metal cells with significant excess lithium, resulting in a dramatically reduced practical energy density. In contrast, anode-free cells do not utili...

We present a wide range of testing results on an excellent moderate-energy-density lithium-ion pouch cell chemistry to serve as benchmarks for academics and companies developing advanced lithium-ion and other “beyond lithium-ion” cell chemistries to (hopefully) exceed. These results are far superior to those that have been used by researchers model...

Fast-charging lithium-ion cells require electrolyte solutions that balance high ionic conductivity and chemical stability. The introduction of an organic ester co-solvent is one route that can improve the rate capability of a cell. Several new co-solvent candidates were identified based on viscosity, permittivity (dielectric constant), and DFT-calc...

Adding esters as co-solvents to Li-ion battery electrolytes can improve low-temperature performance and rate capability of cells. This work uses viscosity and electrolytic conductivity measurements to evaluate electrolytes containing various ester co-solvents, and their suitability for use in high-rate applications is probed. Among the esters studi...

One goal of researchers focusing on lithium-ion batteries for electric vehicles is to decrease the time required for charging. This can be done by several methods, including increasing the electrolyte transport properties. Methyl acetate, used as a co-solvent in the electrolyte, has been shown by a number of researchers to increase cell rate capabi...

An automated system was developed to measure the viscosity of fluids as a function of temperature using image analysis tracking software. An Ostwald viscometer was placed in a three-wall dewar in which ethylene glycol was circulated using a thermal bath. The system collected continuous measurements during both heating and cooling cycles exhibiting...

Plating rates and Ni co-deposition were measured for electroless Cu plating baths without and with an added proprietary stabilizer system. The bath has formaldehyde as reducing agent and tartrate as complexing agent. The concentrations of Ni and stabilizer codetermine the plating rate. We investigated this bath over a wide range of compositions, va...

The effects of three esters incorporated as co-solvents in 1.2MLiPF6 EC:EMC:DMC (25:5:70 by volume %) electrolyte were studied in Li[Ni1-x-yCoxAly]O2/Graphite-SiO pouch cells. The esters: methyl propionate (MP), ethyl acetate (EA) and methyl butyrate (MB) were compared in a variety of tests on the cells. Storage tests at 60°C at both 4.2 V and 2.5...