batteries

Scientists at an Australian university have stabilised lithium-sulfur batteries by using sugar on its positive electrode.

A team from the Monash Energy Institute— a cross faculty initiative at the the Monash University— used a glucose-based additive on the positive electrode to create a sustainable rival to lithium-ion batteries.

Test coin-cell prototypes constructed by the team retained 60% capacity after 1,000 cycles.

The team's pouch-cell prototypes reported in their manuscript were 3cm x 5cm, with an overall capacity of ~ 04-0.5Ah. Its recent pouches exceed the ones reported in the article and are ~ 1Ah.

The research by the Monash team, assisted by Australian government agency The Commonwealth Scientific and Industrial Research Organisation, was published in the scientific journal Nature Communications. 

Professor Mainak Majumder, associate director of the Monash Energy Institute, said that in less than a decade the technology could lead to vehicles travelling more than 800km without recharging. 

In theory, lithium-sulfur batteries can store up to five times more specific energy than lithium-ion batteries—  but the electrodes deteriorate rapidly because the positive sulfur electrode weakens due to substantial expansion and contraction causing the negative lithium electrode to become contaminated by sulfur compounds.

Last year, the Monash team opened the structure of the sulfur electrode to accommodate expansion and make it more accessible to lithium. 

Now, by incorporating sugar into the web-like architecture of the electrode they have stabilised the sulfur, preventing it from moving and blanketing the lithium electrode.

First author and PhD student Yingyi Huang and her colleagues were inspired by a 1988 geochemistry report that described how sugar-based substances resist degradations in geological sediments by forming strong bonds with sulfides.

Dr Mahdokht Shaibani, second author and Monash researcher, said: “While many of the challenges on the cathode side of the battery has been solved by our team, there is still need for further innovation into the protection of the lithium metal anode to enable large-scale uptake of this promising technology – innovations that may be right around the corner.”

The process was developed by the Monash team with significant contribution from Dr Matthew Hill’s research group in CSIRO Manufacturing.

Energy research and innovation company Enserv Australia hopes to develop and manufacture the batteries in Australia.

A spokesmn for Monash told BEST: "Certain aspects have been licensed to Enserv Australia. Whilst it has been an absolute delight to work with Enserv group,  currently, our engagement with Enserv  on this battery technology has been completed.  We are looking forward to working with new venture partners to take the technology forward. It is our expectation that advanced prototypes will supercede the current technology at our disposal

Mark Gustowski, managing director of Enserv Australia, said his firm would look to use the technology to enter the electric vehicles and electronic devices market. 

He said: “We plan to make the first lithium-sulfur batteries in Australia using Australian lithium within about five years.”

New salts for lithium-ion

Scientists at the Monash University School of Chemistry in Australia have developed an alternative to hexafluorophosphate salt for lithium-ion battery electrolytes.

The electrolyte was developed under the leadership of professor Doug MacFarlane and Dr Mega Kar alongside battery developer Calix.

The synthesised battery grade fluoroborate salt, made using a recrystallisation process, was found to be stable even when exposed to air. 

When used in a battery with lithium-manganese-oxide cathodes, the cell achieved more than 1,000 cycles, even after atmospheric exposure, reported the team.

Researchers at the Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) have developed a robotic disassembly system for used lithium-ion batteries from electric vehicles.

The robots accelerate disassembly and make the process of breaking any type of battery stack safer for workers, while increasing throughput.

ORNL project team member Jonathan Harter estimates the automated system could handle 100 or more battery stacks in the time it takes to disassemble 12 by hand.

The system breaks down the battery stack to sections, then to modules, then to cells. 

ORNL has developed other processes to break down those cells to the pouch/anode/cathode/separator components. They have also developed control technologies to repurpose spent EV batteries for grid energy storage.

Economically feasible recyling

Harter believes that to make recycling more economically feasible, it must be done at high throughput and be flexible enough to process multiple consumer products in a single facility. 

He said: “Industry is not limited on the amount of batteries they can take into this process. There is a significant backlog already accumulated. 

“The limiting factor is the time it takes to perform the electrical discharge and perform disassembly manually.”

The robots remove bolts and other housing regardless of any remaining charge, whereas human operators must undertake lengthy processes to discharge used batteries before breaking them down manually. 

The automated system was developed as part of DOE’s Critical Materials Institute (CMI).

It can be programmed to access the individual battery modules for refurbishment or reuse as stationary energy storage, or the batteries can be taken down to the cell level for separation and materials recovery.  

The work builds on expertise developed in previous ORNL projects for the CMI that focused on robotic disassembly of hard drives for recovery of rare-earth magnets. 

Engineers also proved that those magnets can be directly reused in electric motors.

The researchers follow the same protocol each time: breakdown the used component manually and collect data on that process to create the robotic tools and controls needed to drive an automated system.

The next step could be building the process up to commercial scale, and applying the same kind of disassembly system to electric vehicle drive trains for recovery of materials such as rare earth magnets, copper, steel and intact power electronics. 

The system was developed and demonstrated at ORNL’s Grid Research Integration and Deployment Center.

Researchers from the University of Science and Technology of China (USTC) have designed a material to make solid-state lithium-ion batteries cheaper and more effective.

The team identified different types of solid electrolytes, but found chloride solid electrolytes exhibited the desirable characteristics of both sulfide and oxide systems, including high ionic conductivity, deformability and oxidative stability.

The team designed and synthesised the material, Li2ZrCl6 (LZC), which boasts low materials cost and excellent humidity tolerance— challenges that have hindered the mass production of solid electrolytes.

An article outlining the research was published in the science journal Nature Communications. 

The raw material cost of LZC at 50μm thickness is $1.38/m^2, compared to the cheapest chloride system in the literature ($23.05/m²), and below the $10/m² threshold for ensuring the cost competitiveness of all-solid-state batteries, said the researchers. 

Furthermore, LZC is stable in an atmosphere with 5% relative humidity, so the strict requirements for atmosphere during synthesis and storage, like those for sulfide solid electrolytes, are no longer needed.

LZC possesses high ionic conductivity (0.81 mS cm-1) and is compatible with 4V-class cathodes. 

A cell with a LiNi0.8Mn0.1Co0.1O2 cathode and a LZC solid electrolyte delivered a stable specific capacity of about 150mAh g-1 after 200 cycles at 200 mA g-1 without considerable fade, said the researchers.

More importantly, the above advantages in mass production have been achieved without sacrificing any of the attractive characteristics of chloride solid electrolytes, said professor Ma Zhiming.

Zhiming said: "All-solid-state Li batteries play an important role in achieving the goal of 'peak carbon dioxide emissions' and 'carbon neutrality'.

"The achievement of both cost-effectiveness and high performance of Li2ZrCl6 removes a major obstacle to the commercialization of such batteries."

The team will now try other 4+ cations, denoted as M, to synthesize Li2MCl6 solid electrolytes, and strive to make both better and more affordable all-solid-state batteries.

US electric vehicle maker Tesla is set to pay $1.5 million to settle a lawsuit regarding the voltage restriction of batteries amid a spate of fires in their Model S sedans.

The suit, filed in August 2019, alleged that Tesla reduced the maximum voltage to which battery packs in around 1,743 Model S vehicles could be charged.

The over-the-air software updates to battery management systems in May 2019 related to charging and thermal control following a number of incidents where batteries caused fires in their Model S vehicles.

Plaintiff David Rasmussen launched the claim after the software update reportedly reduced his Model S vehicle’s battery by 8kWh, decreased range and increased charging times.

Lawyers for the owners who sued said the "voltage limitation was temporary, with a 10% reduction lasting about 3 months, and a smaller 7% reduction lasting another 7 months before the corrective update was released in March 2020," reported news outlet Reuters.

However, Tesla was found to have fraudulently concealed information the cars would “experience a significant decrease in the total amount of range, and other performance issues”, according to the court paper.

The settlement is pending approval by federal district court of the United States District Court for the Northern District of California. 

A hearing to finalise the proposed settlement is scheduled for 9 December which, if approved, would see the 1,743 class members paid $625 each. 

Tesla did not respond to BEST’s request for a comment.

Model S electric vehicle fires

The over-the-air software update followed a number of fires in Tesla’s Model S cars.

The fires included: a “single battery module” causing a Model S in Shanghai, China, to catch alight in April, 2019; a Model S fire in San Francisco, US, in May 2019; also in May 2019, a Model S caught alight in Hong Kong; in July 2019 a Model S caught alight in Germany.

To date, Tesla has failed to provide its customers with any further information regarding the cause of these fires and has failed to inform customers as to which vehicles are potentially at risk of catching fire, according to court papers.

Court filings say 1,552 of the affected Tesla Model S sedans have had their batteries’ voltage fully restored, and 57 received full battery replacements. 

A subsequent update restored about 3% of the battery voltage in the vehicles, and a third update released in March 2020 was designed to fully restore the batteries’ voltage over time as the vehicles are driven, the settlement documents said.

BEST has been reporting on Tesla fires as far back as 2013 when the company faced a costly recall after three fires in five weeks on its Model S called into question the safety of the battery. 

Is China on the verge of banning the use of second-life lithium-ion batteries in large-scale energy storage systems (ESS) amid a spate of fires this year?

The halt will continue until a “breakthrough in battery consistency management technology and a sound power battery performance testing and evaluation system” is developed, according to reports from China media group Caixing.

The ceasing of secondary battery use follows the National Energy Administration issued a draft report ‘Regulations for the Management of New Energy Storage Projects’ on June 22.

What capacity constitutes “large-scale” is not clear.

The Caixing report stated: “According to industry sources, there are few energy storage projects that can be called cascade utilization of large-scale power batteries. In addition, the document does not specify the criteria for defining "large-scale" projects.”

The draft also proposes that completed and operating projects should be regularly evaluated and monitored, and supervision should be strengthened.

Cascade utilisation generally refers to using a battery with less than 80% capacity in EESs for commercial and residential, and telecom base station applications.

In January, an explosion at a China recycling plant owned by lithium-ion battery giant Contemporary Amperex Technology (CATL) killed one person and injured 19 more.

In April, two firefighters died when they were putting out a fire in an energy storage power station in Fengtai District of Beijing, according to the China Daily news outlet.