Elucidating Zn and Mg Electrodeposition Mechanisms in Nonaqueous Electrolytes for Next-Generation Metal Batteries
The development of nonaqeuous electrolytes enabling reversible and efficient deposition/stripping of multivalent metals has been hindered because of the complexity of electrolyte properties and behaviors. Different cations exhibit different deposition efficacy. Our research explores Zn and Mg deposition mechanisms and explains differences between the two cations.
Significance and Impact
Our research shows that Mg and Zn electrodeposit by two fundamentally different mechanisms. Mg requires a chemical step in addition to an electron transfer step, while Zn just requires an electron transfer step. This result suggests that facile Mg deposition may be reached at higher temperatures whereas Zn electrodeposition may be enhanced by increasing electron-transfer rate constant, likely through additives.
CVs of Zn deposition at a ultramicroelectrode (UME) exhibit an independent relationship between current density and scan rate indicating a simple two-electron reduction mechanism.
CVs of Mg deposition at a UME show an inverse dependence between scan rate and current density suggesting a more complicated chemical-electrochemical process.
By coupling electrochemistry with COMSOL simulation, our study provides kinetic parameters and insights central to the Zn and Mg electrodeposition/dissolution processes.
Addressing Passivation in Lithium-Sulfur Battery Under Lean Electrolyte Condition
Identification and understanding of cycle life limiting factors of Li-S batteries under lean electrolyte conditions; Identification of a NH4TFSI additive to effectively mitigate the uncontrollable passivation issue arising from accumulation of insulating Li2S.
Significance and Impact
NH4TFSI additive enhances the dissociation of Li2S, and largely reduces the insoluble and insulating Li2S particles in sulfur cathodes, which facilitates reversible and sustainable redox reactions and significantly improves the cycle life of a Li-S battery under lean electrolyte conditions.
The cycle life of Li-S batteries under lean electrolyte condition largely depends on the electrolyte to sulfur ratio (E/S). SEM, NMR and XPS measurements indicate that a low E/S ratio creates a critical passivation issue resulting from uncontrollable and irreversible accumulation of Li2S.
The NH4TFSI additive increases the solubility of Li2S and other short-chain species effectively by tailoring the ionic strength of the solution and promoting Li2S dissociation.
SEM and EIS measurement indicate that NH4TFSI enables a homogeneous sulfur cathode and Li anode morphology with sustainable reaction interfaces upon cycling under lean electrolyte conditions.
Are Ikea’s $7 Rechargeable Batteries Actually Pricey Eneloop Pro AAs in Disguise?
If you cheap out on alkaline batteries, there’s a noticeable difference in performance. But that might not be the case with rechargeable nickel-metal hydride batteries made in Japan. As Matthew Eargle discovered, the cheap LADDA rechargeables that Ikea sells might actually be rolling off the same production line as Panasonic’s pricier Eneloop Pro batteries.
To help add credence to his theory, which is thoroughly explained in this video, Eargle first digs into the long history of corporate takeovers and partnerships that resulted in the Sanyo-developed Eneloop batteries being taken over by Panasonic, with the newer Pro versions now being manufactured at the last remaining Fujitsu battery factory in Japan. If you find a pack of 2,450 mAh rechargeable nickel-metal hydride batteries, it’s almost guaranteed you’ll find the words “Made in Japan” somewhere on the packaging.
But Panasonic is never going to cop to the fact that Ikea is essentially selling its pricier product with a boring label and a much cheaper price tag, so Eargle went one step further by thoroughly comparing the performance of a four-pack of Eneloop Pros versus a four-pack of Ikea LADDAs. After averaging the results, the Ikea batteries demonstrated the exact same discharge patterns as Panasonic’s did, and there was only five-one-hundredths of a percent performance difference between the two brands.
Without sneaking into the Japanese factory to see the actual labels being applied, Eargle can’t 100 percent confirm that the Panasonic and Ikea batteries are exactly the same underneath. Even if they were, there could still be a minor quality control difference discovered during the factory’s testing that results in batteries being labelled as Eneloop Pros or LADDAs. But as a result of his research and continued testing months later, Eargle’s 99.957 percent sure you’re secretly getting a sweet deal on a set of Eneloop Pros when you buy a pack of Ikea LADDAs.
Apple may secure its own battery materials to avoid shortages
According to the report, Apple is seeking to lock down a long-term deal, securing several thousand metric tons a year, for a last five years. The move puts Apple in direct competition with other big players who are also looking for a similar agreement, and advantage. BMW, Volkswagen and Samsung’s own battery division are thought to be engaged in similar negotiations for their own EV projects.
It’s clear from the piece that Apple is only seeking to secure material for batteries that go inside its consumer hardware. CEO Tim Cook has been open about his company’s interest in the “autonomous systems” market, but wouldn’t be drawn on what exactly was being worked on. Rumors out of Apple’s self-driving car project, codenamed Titan, suggest that work is now underway on a plug-and-play system for third party manufacturers.
Procuring a supply of a highly-coveted resource is something that Apple has done several times in the past, often with market-altering results. Perhaps most famously, the company purchased a significant chunk of the world’s NAND Flash supply in 2009, effectively shutting out its competitors.
Dyson’s debut EV might not showcase its next-gen battery tech
Dyson has been working on solid-state batteries for a while, first investing in and then acquiring in 2015 a company specializing is such technology called Sakti3. Solid-state batteries are much safer than their liquid-based counterparts, charge faster and have a higher energy density, meaning EVs could go significantly further with no change in weight. BMW, Toyota, Fisker, Google and others are pursuing this step change in battery tech, but it’s thought Dyson could be the first to market with a solid-state EV, and the main reason it was moving into this new, competitive market in the first place.
Dyson has committed over $2 billion to its EV plans, with half of that going to solid-state battery R&D. Speaking to the FT, James Dyson would only say the company has been “investing heavily in new battery technology, solid-state battery technology… but those sorts of technologies can take some time to get there.” He added that Dyson is still on track to launch an EV in 2020/21, which is slight slip from the “by 2020” window previously announced. The FT‘s sources claim the first model could rely on lithium-ion power, however, with the second and third vehicles switching to solid-state tech.
Insiders said the first car would be a beta test of sorts, used to firm up logistics, the supply chain and to gauge public interest with a production run of just a few thousand vehicles. Later models will be manufactured as mass-market products, sources said, not that Dyson would confirm any of these rumors. Currently, the company still hasn’t settled on a manufacturing base and part suppliers, so there’s plenty still to figure out. But if the FT‘s contacts are to be believed, Dyson committing to a three-vehicle roadmap means it’s serious about creating a new side to its business. If the company ends up leaning on current-gen battery tech for its initial outing, though, it could sacrifice the splash a new entrant pulling up in possibly the first solid-state EV would make.
Boeing HorizonX invests in Berkeley aerospace battery tech startup
Boeing’s HorizonX is the aerospace company’s vehicle for making investments in promising next-generation startups and technology, and it just placed its latest bet: funding in Cuberg, a Berkeley-based battery tech startup that has a founding team including Stanford University researchers.
Battery tech is still one of the most frustrating roadblocks any company encounters when trying to build electric vehicles and other battery-powered technology and transportation. For Boeing, there are plenty of potential upsides to building out batteries that can last significantly longer than those available via today’s tech.
Cuberg’s work focuses on batteries with especially high energy density, while retaining thermal safety. That basically means they hope to be able to build a new type of battery cell that can hold a lot more power for vehicles to use, while also not catching fire.
That’s not all, however: Cuberg’s approach would result in a manufacturing process that could be used in exiting large-scale battery factories. The end result is a relatively smooth transition process from existing manufacturing to building next-gen cells, which obviously means a lot less upfront investment when it comes to taking the new manufacturing process to scale.
Cuberg was originally founded in 2015, and this market the first time Boeing HorizonX has invested in any energy storage companies since its inception last year. The funding, which is described as a “second seed” round, should help Cuberg grow its team and its facilities in preparation for fully automated manufacturing.
Tesla Employees Say Gigafactory Problems Are Worse Than Known
An anonymous reader quotes a report from CNBC: Tesla’s problems with battery production at the company’s Gigafactory in Sparks, Nevada, are worse than the company has acknowledged and could cause further delays and quality issues for the new Model 3, according to a number of current and former Tesla employees. These problems include Tesla needing to make some of the batteries by hand and borrowing scores of employees from one of its suppliers to help with this manual assembly, said these people. Tesla’s future as a mass-market carmaker hinges on automated production of the Model 3, which more than 400,000 people have already reserved, paying $1,000 refundable fees to do so. The company has already delayed production, citing problems at the Gigafactory. On Nov. 1, 2017, CEO Elon Musk assured investors in an earnings call that Tesla was making strides to correct its manufacturing issues and get the Model 3 out. But more than a month later, in mid-December, Tesla was still making its Model 3 batteries partly by hand, according to current engineers and ex-Tesla employees who worked at the Gigafactory in recent months. They say Tesla had to "borrow" scores of employees from Panasonic, which is a partner in the Gigafactory and supplies lithium-ion battery cells, to help with this manual assembly. Tesla is still not close to mass producing batteries for the basic $35,000 model of this electric sedan, sources say.
Toyota and Panasonic explore ‘prismatic’ EV batteries together
The agreement is just a first step, but shows the increasing need for automakers and battery companies to work together. Toyota recently unveiled plans, working with Mazda and Suzuki, to launch a new lineup of EVs starting in around 2020. Until recently, the company had been focused on building hybrid, plug-in hybrid and hydrogen cars exclusively.
Panasonic is the leading EV battery manufacturer, most famously supplying batteries for Tesla’s Model S, 3 and X. It also makes the batteries for Toyota’s current plug-in hybrid Prius cars and has a 29 percent total share of the market, Reuters notes. Other leaders are LG Chem, which builds the batteries for two best-selling EVs, the Renault Zoe and Chevy Bolt, Samsung, and China’s BYD Co.
Toyota and Panasonic won’t have to deal with thorny issues like battery chemistry to make better prismatic cells, which are already used on the Bolt and other vehicles. Rather, they’ll just have to use their engineering and research chops to refine them so that they’re cheaper, safer and more reliable. The payoff could be longer-range, faster-charging and lighter or smaller EVs.
Right now, Toyota and Panasonic are just studying the feasibility of developing these types of batteries together, but there’s a decent chance this will turn into a concrete plan. Batteries are the big sticking point for EV development, so the more development, the better.
Samsung Develops ‘Graphene Ball’ Battery With 5x Faster Charging Speed
Heart44 writes: A number of outlets are reporting a Samsung laboratory breakthrough allowing smaller and faster charging lithium-ion batteries using three-dimensional graphene. Digital Trends reports: "Scientists created a ‘graphene ball’ coating for use inside a regular li-ion cell, which has the effect of increasing the overall capacity by up to 45 percent and speeding up charging by five times. If your phone charges up in 90 minutes now, that number will tumble to just 18 minutes if the cell inside has been given a graphene ball boost. What’s more, this doesn’t seem to affect the cell’s lifespan, with the team claiming that after 500 cycles, the enhanced battery still had a 78 percent charge retention. The graphene coating improves the stability and conductivity of the battery’s cathode and electrode, so it’s able to take the rigors of fast charging with fewer downsides." The technical paper describing how the graphene ball works and how it’s produced is published in the journal Nature.
Lithium Self-Discharge and its Prevention: Direct Visualization through In-Situ Electrochemical STEM
We show that Li anode morphology and solid electrolyte interphase structure is dependent on surface compression, which affects the amount of self-discharge for an exciting solvent-in-salt electrolyte. Additionally, we show that coatings can suppress self-discharge.
In engineering batteries that contain a Li-metal anode for certain electrolytes, we show that cell compression and coatings will greatly impact the cell stability and performance.
Sandia-microfabricated electrochemical TEM discovery platform, identified key factors in controlling SEI character and Li-metal morphology.
Li self-discharge was improved with cell compression and could be further improved with the use of a protective coating on the current collector, which also showed improved Li nucleation density.
In-situ TEM cells are not compressed, so experiments must be carefully designed to ensure relevance.