Lithium News

Argonne National Laboratory has undertaken a study of the basic mechanisms that allow electrolyte additives to dramatically improve the performance and cycle-life of lithium ion batteries.

Battery researchers have discovered one reason why lithium ion batteries gradually lose their ability to store energy: a degradation of the electrolyte due to interactions with the cathode materials. Recent research is adding to an understanding of why this degradation occurs and how it can be controlled through the addition of additives to the electrolyte.

Batteries are made up of an anode (negative electrode) and a cathode (positive electrode) separated by an electrolyte through which ions can flow. In a lithium ion battery, that anode is usually a carbon graphite material that can accept and store lithium ions between its layers of carbon atoms. The cathode is typically a metal oxide composed of nickel, manganese, cobalt, and lithium. It is the cathode that limits the maximum storage capacity of a lithium ion battery.

The typical electrolyte for a lithium ion battery is a lithium salt (typically lithium hexafluorophosphate, LiPF6) mixed into an organic solvent. That solvent is often a mix of ethylene carbonate, dimethyl carbonate, propylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The electrolyte must allow the passage of lithium ions between the electrodes during charging and discharging. It must also prevent the passage of electrons to avoid self-discharging of the battery cell.

Electrolytes must not react with either the anode or cathode materials or the result will be a gradual degradation in battery performance. This is not a problem for the carbon of the anode, but the metal oxides in the cathode present a problem. When the cathode is in contact with the electrolyte over a long period of time, the liquid electrolyte begins to degrade, reducing battery performance.

Boosting Performance

The good news is that a performance-boosting additive can be added to the electrolyte. The material is called tris(trimethylsilyl)phosphite, or TMSPi. According to a press release from Argonne National Laboratory, which has studied TMSPi in lithium ion batteries, the additive modifies the cathode surface. In doing so, it forms a protective layer to help reduce the degradation of the electrolyte near the cathode surface.

According to Argonne senior materials scientist Daniel Abraham, the mechanism by which TMSPi works in the lithium ion battery was a mystery—until now. A recently published article in The Journal of Physical Chemistry describes work undertaken by Abraham and Argonne to understand how the additive provides protection that enhances battery performance.

According to the Argonne press release, what is surprising about the latest research is the discovery that the TMSPi molecule itself is not involved directly in the protection of the cathode. The release reports, “The active component is a different molecule, PF2OSiMe3, which is chemically derived from TMSPi.” (The “Me” in this formula represents a methyl group.) The compound slowly forms as the lithium salt in the electrolyte reacts with the TMSPi.

Benefits

Abraham calls the process “pickling” and notes that it has several beneficial effects. First, the reaction product reduces the rise in electrical resistance that normally occurs after many charge and discharge cycles. Slowing of the lithium ions traveling between the cathode and anode and a change in the cathode chemistry due to an interaction with the electrolyte are the cause of this rise in resistance. The new active compound decreases the rise while allowing faster charging and discharging of the lithium ion cells.

Another beneficial effect of the TMSPi-derived molecule is that it reduces the loss of cobalt and manganese transition metals from the cathode into the electrolyte and eventually reaching the anode. The result of the loss and transfer can be a degradation of performance after many cycles. This is prevented by the presence of the active molecule.

Physical Understanding

While performance improvements were straightforward to measure, an actual physical understanding of the mechanisms involved required more work. A computational study at Argonne revealed that the reaction product PF2OSiMe3 binds to reaction centers on the surface of the cathode without removing oxygen from the surface. According to the release, “This surface-bound molecule can further react with the electrolyte, transforming into a still-stronger binding molecule that permanently caps the reaction centers on the cathode, stabilizing the interface between liquid electrolyte and solid electrode.” Argonne’s research showed that the performance of the battery actually improves with age as more of these transformations occur.

There are important practical applications from these results. “Now that we better understand the mechanism for the cathode-protective action by the phosphite, we can be more systematic in finding new ways of achieving and improving this pickling of the electrolyte additive,” said Abraham.

Cleve Hill Solar Park, the joint venture (JV) of Hive Energy and Wirsol intending to develop a 350MW+ solar farm on the Kent coast of England, has yet to make any decisions regarding the battery storage element of its plans, contrary to media reports.

Stories emerged in the UK’s mainstream press last weekend linking battery giant Tesla to the project, suggesting that Elon Musk’s company was intending to develop the energy storage element of the facility.

But the companies behind the project have strongly refuted those reports, stressing that no decisions – including on capacity and technology type – have been made.

“Cleve Hill Solar Park Ltd. is proposing to include battery storage technology in addition to the PV array in their Development Consent Order (DCO) application. Whilst the type and final number of batteries for the project is unknown, a range of scenarios will be presented in the application for the project.

“Battery storage technology is a key part of the government’s Industrial Strategy. The technology can be used in a number of ways in support of renewable energy generation including time shifting output and balancing frequency response. Battery storage technology will be part of the solution to help the grid shift from fossils fuels to renewable energy. By acting to smooth the supply of renewable energy to the grid, battery storage will play a key role in enabling an integrated low carbon energy supply.

“Battery storage technology forms an intrinsic part of the proposal for the Cleve Hill Solar Park and is an exciting part of the future of renewable energy generation,” a statement issued to our sister site covering the UK PV industry, Solar Power Portal, read.

Discussions around the final capacity and indeed the supplier of the battery storage facility may also centre on the desired duration, or mix of different battery durations. The government’s decision to de-rate battery storage facilities competing in the Capacity Market owing to their duration stands to drive interest in longer duration storage and new technologies, with some developers investigating the potential for flow batteries to be deployed at scale.

Reporting over the weekend by outlets including British daily newspapers The Times and The Daily Mail claiming Tesla CEO Musk was already lining up the project were slammed by some experts via social media for other innacuracies. Meanwhile in California, investor-owned utility (IOU) PG&E put forward for approval four projects which included a 182.5MW, four hour duration (730MWh) Tesla project.

Tesla’s largest-ever Powerpack installation may be coming to north-central California. Pacific Gas and Electric Company (PG&E) applied to the California Public Utilities Commission (CPUC) for approval for a utility-owned 182.5 MW energy storage farm using Tesla Powerpacks at the company’s South Bay – Moss Landing Energy Storage site.

PG&E also sought approval for three third-party owned energy storage projects. One of the third-party projects will have a larger initial capacity than the Tesla project. The Tesla project, however, would have an expansion capacity of 1.1 GW.

The storage projects’ purpose is to help keep electrical power levels even for PG&E customers. The storage facilities would feed power to the grid when consumption exceeds normal levels and during blackouts or other service interruptions.

The three additional projects and their respective storage capacities are Dynegy Marketing and Trade, LLC, 300 MWh; Hummingbird Energy Storage LLC, 75 MW; and Micronoc Inc., 10 MW. All four projects would use lithium-ion battery storage technology and be located in the utility’s South Bay – Moss Landing area, which services from the South Bay area south to California’s central coast. The coverage area encompasses Silicon Valley.

The projects will have enough storage capacity to provide power to the region’s electrical grid for four hours. If the Tesla project expands to the max, its discharge duration will increase to six hours and provide six times as much energy as the initial installation.

Tesla’s 100 MW battery farm in South Australia, switched on December 1, 2018, has already proved its value. In the first four months of service, the costs for ancillary services to fill in for power interruptions in the region decreased by a full 90 percent, according to McKinsey and Co.

PG&E is looking for improved service and reduced costs from the proposed projects.

“Energy storage plays an increasingly important role in California’s clean energy future, and while it has been a part of PG&E’s power mix for decades – starting with the Helms Pumped Storage Plant in the 1980’s – recent decreases in battery prices are enabling energy storage to become a competitive alternative to traditional solutions. As a result, we believe that battery energy storage will be even more significant in enhancing overall grid reliability, integrating renewables, and helping customers save energy and money,” said Roy Kuga, vice president, Grid Integration and Innovation, PG&E.

Protean Energy Ltd has provided an important update regarding its V-KOR vanadium redox flow battery (VRFB) electrolyte technology facilitated by the company’s 50 per cent owned subsidiary, KORID Energy (KORID).

The recent development of a new generation vanadium electrolyte by KORID has achieved improvements of up to 25% in energy density, representing a significant increase in electrolyte efficiency and cost performance.

This technical achievement has material positive implications for the V-KOR battery’s levelised cost of storage given that electrolyte represents between 30 per cent and 50 per cent of the total energy storage system cost of VRFBs.

KORID is also researching production of electrolyte using ammonia metavanadate (NH4VO3) which has the potential to markedly reduce the production cost of electrolyte.

It should be noted that this is in research stage, so investors should seek professional financial advice if considering this stock for their portfolio.

Korid has impressive product and patent profile

KORID owns a suite of patents covering the battery stack and intellectual property on electrolyte technology developed to date, with US$3 million spent in research, development, testing and intellectual property (IP) protection.

KORID has also recently completed testing of over 3,000 cycles on a V-KOR five kilowatt stack, representing 9 years of full daily cycles with no significant degradation of performance.

The majority of the cost related to VRFB systems is within the vanadium electrolyte and is resultant in the extensive research into the optimisation of electrolyte technology as a high priority.

VRFB’s proven lifespan of up to 20 years

The Vanadium Redox Flow Battery (VRFB) was invented over 20 years ago, and there have been several implementations of this technology in various countries.

The V-KOR systems use vanadium ions in different oxidation states to store energy in the form of two liquid electrolytes.

Importantly, VRFBs are proven to have excellent durability and life spans up to 20 years.

Energy storage capacity independent of power rating

A significant point of difference with VRFB systems is that their energy storage capacity is independent of the power rating.

This allows them to be designed for highly specific energy and power requirements, making them well suited to applications with large energy storage capacity specifications.

These batteries are currently used for grid scale energy storage applications where large-scale and long duration electrical energy storage is required.

Potential accelerated uptake from renewable energy generators

V-KOR was developed in response to the growing demand for more efficient energy storage solutions to support intermittent renewable energy production.

This technology is an ideal solution for rapidly growing intermittent renewable energy generation sources such as solar and wind.

Importantly, the developers are in a position where they can build batteries to scale, fitting a wide range of applications which effectively opens up multiple markets, essentially generating revenues from a broad client base.

Protean offers battery solutions from 2 kilowatt to 5 megawatt or larger built to order for commercial, industrial and grid scale applications.

V-KOR is a commercial stage technology that offers a rechargeable flow battery with the ability to store high levels of energy for longer and with a greater life expectancy than existing battery solutions.

In somewhat of a departure from their normal fare of heavy metal mods, [Make It Extreme] is working on a battery pack for an e-bike that has some interesting design features.

The guts of the pack are pretty much what you’d expect – recovered 18650 lithium-ion cells. They don’t go into details, but we assume the 52 cells were tested and any duds rejected. The arrangement is 13S4P, and the cells are held in place with laser-cut acrylic frames. Rather than spot weld the terminals, [Make It Extreme] used a series of strategically positioned slots to make contacts from folded bits of nickel strip. Solid contact is maintained by cap screws passing between the upper and lower contact frames. A forest of wires connects each cell to one of four BMS boards, and the whole thing is wrapped in a snappy acrylic frame. The build and a simple test are in the video below.

While we like the simplicity of a weld-less design, we wonder how the pack will stand up to vibration with just friction holding the cells in contact. Given their previous electric transportation builds, like this off-road hoverbike, we expect the pack will be put to the test soon, and in extreme fashion.

The only thing more impressive than a well-designed tiny house…is a tiny house that floats. This boathouse, called “Le Koroc,” was designed by the Quebecois boat makers Daigno as an efficient alternative to heftier floating homes. The laminated white cedar home stretches 8 by 24 feet and weighs 5,700 pounds.

Unlike most houseboats, “Le Koroc” is meant to sail. The dwelling sits on three aluminum pontoons, and it’s light enough to scoot around a body of water without using too much energy. For the energy that is used, there’s a 265 Watt solar panel on the roof that powers the home’s lights and refrigerator and a propane tank for the rest.

Inside, the boathouse has a full bathroom and full kitchen with a dinette that turns into a bed by lowering the table and adding cushions. The ‘living room” is actually an outdoor deck that has chairs optimally positioned for fishing, and a table for eating the fish you just caught.