Battery Metals

Short bursts of current can flatten spiny growths on a battery’s lithium metal anode. This method of self-healing dendrites, which can cause a battery to catch fire, could be used to make more powerful batteries viable, the researchers say.

Researchers started experimenting with lithium metal anodes in the 1970s to increase the energy density of rechargable batteries. An electrode with a thin layer of lithium can store more energy-carrying atoms than one made from porous materials like graphite. But they soon found that lithium anodes can catch fire.

When a lithium–ion battery charges, lithium ions travel from the cathode to the anode; the ions flow the other way during discharge. At a lithium metal anode, lithium ions leave and return to the surface unevenly. This means that after several charging cycles, spiny projections called dendrites begin to grow from the electrode’s surface. As these lithium dendrites grow, they can pierce the membrane separator in the middle of the battery, touch the cathode and short circuit the cell. This can starts fires.

Scientists manage dendrite growth by coating the anode with materials that partially block, redirect or contain them. Now, Nikhil Koratkar at Rensselaer Polytechnic Institute in the US and colleagues have developed a way to flatten dendrites before they start causing problems.

The researchers charged a coin cell with a lithium foil anode and cathode for 50 cycles at current densities ranging from 0.75mA/cm² to 15mA/cm². Then they removed the anode from each cell and examined its surface using scanning electron microscopy. As expected, dendrites formed on the electrode at lower current densities, which reflected low rates of charging and discharging. The particles got larger as the current density increased.

‘Even though we saw that the dendrites were getting worse, we went to higher charge/discharge rates,’ Koratkar says. ‘At a certain point, we found a new regime of dendrite growth, where things started to get better.’ At current densities greater than 9mA/cm², the dendrites began to merge and the electrode surface was smoothed out.

Heat transfer simulations revealed that a current density of about 15 mA/cm² increased the temperature around the dendrites about 40–60°C. This elevated temperature is high enough to allow lithium atoms at the dendrite tips to diffuse to the electrode surface, but not high enough to damage other components in the battery.

Managing dendrites with bursts of high current is counterintuitive to the idea that higher current densities increase dendrite formation, says Amartya Mukhopadhyay at the Indian Institute of Technology Bombay. Since dendrite formation cannot be prevented, flattening them with periodic pulses of current is a fantastic way to manage them because it does not allow them to grow too long and it does not require extra materials inside a cell, he says. While the researchers tested this approach in a lithium–sulfur cell, in principle, it could be used with any battery chemistry that uses a lithium metal anode, he says.

A SYDNEY family has reduced its Energy Australia power bill to $0 a quarter after turning to solar power and battery storage to meet the household’s energy needs and guard against future price rises.

While some members of the government cling to coal, advances in renewable energy systems are providing genuine alternatives for Aussie households — and the Fenech family is cashing in.

The family was one of the first in the country to adopt a home solar power solution from German company Sonnen that provides solar panels and battery storage and links the system to all the other Sonnen batteries in Australia — essentially creating a virtual power plant for its users.

“Sonnen links us all together so basically Sonnen becomes our energy retailer,” Steve Fenech told news.com.au.

Users can choose between different plans to receive a guaranteed annual allowance of energy for a monthly fee of $30, $40 or $50 (plus GST) and in return some of the energy stored in your battery is used to assist in the stabilisation of the electricity grid resulting in reducing your energy bills, Sonnen says.

The German company promotes its SonnenFlat product as taking away all the risk of a rise in future energy prices.

The Fenechs were among the first Australians to install a SonnenFlat system in their Pagewood home in Sydney’s east after it launched in July last year and are expecting to save more than $2520 on their yearly power bill in 2018.

It now costs them just $44 per month to power their two storey, four bedroom home with three bathrooms and fully ducted airconditioning.

Previously, the Fenechs were paying $379.40 a year just for grid access without a cent being charged for power usage. Those charges no longer apply as the monthly fee covers both access and power charges with no additional costs applied.

You still need to be connected to the grid, but the battery and Sonnen take over.

“I’m still with Energy Australia but my bill says $0 now. I just don’t need their electricity,” Mr Fenech said.

The whole system cost him $19,000 to install but he expects it to have paid for itself in about five to six years.

“I could have built a system with way more panels, bigger batteries and been completely off the grid but it probably would’ve cost me two to three times more than what I paid for this system now,” he said. He was happy to go with the smaller overhead and have a monthly power bill that was less than what he pays for his mobile phone each month.

A big part of the motivation was to take more control of the household power supply and protect the family budget against rising energy prices.

Without the SonnenFlat system, the family’s power bill would be about $3000 a year. But now, they are expecting to save upwards of $2520 throughout the year by just paying the fixed monthly fee.

“Whose to say the $3000 (a year) is not going to be $4000 or $5000 in two years’ time,” he said. “I thought here’s a chance to get outside of that inevitable price rise.”

The day he sat down with solar battery installer Natural Solar last year to talk about making the move, it just so happened to be the same day that Energy Australia announced a 19 per cent increase to electricity prices in NSW.

“The timing was kind of ironic,” he joked.

Chris Williams is the CEO and founder of Natural Solar — Australia’s largest installer of solar batteries. The company “hand-picks” the best solar energy products and installs a range of battery solutions including the Tesla Powerwall, but Mr Williams said Sonnen is the firm’s “main focus” and was quick to praise the product.

“The Sonnen battery uses Sony-made lithium-iron phosphate cells and, put simply, what that gives you is 10,000 cycles (before the battery stops retaining 100 per cent) and effectively a 20-year life expectancy of the battery unit itself. Most of the solutions on the market are at 10 years and only about 3000 cycles,” Mr Williams said.

“As far as the virtual power plant, sharing of power, aggregation of batteries — that’s really where the SonnenFlat solution is head and shoulders above any other product on the market,” he said.

According to Mr Williams, the cheapest SonnenFlat option, which offers 7500kWh of energy per year for no additional cost “is generally going to be ample to power a three-bedroom household”.

However it’s a modular system, so if you want to increase the battery capacity it is easily done.

“For a 5kW system and an 8kWh battery installed you’re looking at around $17,000 to $18,000 and that’s going to have a return on investment of around six to seven years, if not lower,” he said.

“We’ve been installing batteries for some years now and to see return on investment get to a point like this is great. It’s not just the early adopters that are interested but the mum and dad households who are running the financials and saying this makes sense, we want to save money.”

SONNEN’S BIG AUSTRALIAN PUSH

In February, Sonnen announced it will set up a battery manufacturing hub in South Australia to tap what it sees as the fastest global growth market for solar rooftop storage. The plant will make around 10,000 solar batteries a year for the first five years, once it is set up in six to nine months, said the company’s Australia/New Zealand managing director Chris Parratt.

“We believe that Australia will be the biggest market for storage over the next five years,” Mr Parratt told Reuters.

“At the moment, Germany is the biggest. But we think given the conditions in Australia — high energy prices, an affluent society, high penetration of solar — these things all add up.”

To use the SonnenFlat system, households must be connected to the National Electricity Market. The SonnenFlat solution cannot be offered in Western Australia or to houses connected to the Ergon Network in Queensland.

Load shedding may be behind us, but South Africa’s energy situation leaves much to be desired.

Millions of people, mostly living in rural areas, don’t have access to electricity and are forced to rely on charcoal, paraffin and firewood.

Off-grid solar solutions have the potential to solve this issue.

South Africa may have significantly improved people’s access to electricity since 1994, but 16% of the population – 8 million men, women and children – still has no power.

One reason, besides being unable to afford electricity, is that the national grid doesn’t reach remote, rural areas.

Renewable energy can make a difference, particularly off-grid solutions that don’t require recipients to be connected to the national grid.

This market is exploding, particularly in sub-Saharan Africa.

The 2018 Off-Grid Solar Market Trends report by Lighting Global, an initiative by the International Finance Corporation, the World Bank and the Global Off-Grid Lighting Association, shows that 130 million off-grid home kits, solar kiosks and other devices have been sold across sub-Saharan Africa since 2010.

East Africa is leading the way in this regard.

One of the key players, M-Kopa, has sold more than 600 000 solar-power home kits in Kenya, Tanzania and Uganda since its launch in 2011.

Its goal is to increase that number to 4 million by 2023.

South Africa has jumped on to the off-grid solar bandwagon with innovations such as Shakti Energy, Freedom Won and The Sun Exchange.

One of the latest ventures is SolarTurtle, a local manufacturer of solar-powered kiosks and containers that serve as small business premises.

CEO and founder James van der Walt said: “There is a massive off-grid solar opportunity in South Africa because the demand for electricity is growing, and because of the applicability of solar – the sun shines everywhere.

“I had the idea in 2009 when I was living in Ireland, but I only had the courage to give up my day job as a software engineer when I moved back to South Africa in 2011.”

Van der Walt said that, on his return to South Africa, he contacted the Centre for Renewable and Sustainable Energy Studies at the University of Stellenbosch for feedback.

“They suggested I enrol in their mechanical engineering master’s programme, which I did.”

He decided to focus on off-grid solar applications after visiting 12 schools in the Eastern Cape where the departments of education, and science and technology had started rolling out tablets.

“The problem was their energy supply,” Van der Walt said.

“Government-installed solar panels had been stolen or were broken, and there were issues related to copper cable theft.

“Security is a big issue. It is a well-organised campaign that goes from school to school to steal cables and panels after school when there is no one around. They asked me to have a look at the situation, which I did,” said Van der Walt.

The first pilot container was deployed in June 2015, thanks to support from the Technology Innovation Agency, and the department of science and technology.

More opened in due course, including Nedbank’s first solar branch in Mncwasa, 60km from Mthatha in the Eastern Cape in September.

“This was exciting. Not everyone sees the value of rural electrification,” said Van der Walt.

“I hope more of these contracts come our way soon. There is a business case for new markets, which are people living in informal settlements and rural areas. Many companies seem to be waking up
to this.

“We are making a difference from every direction,” he said, noting that SolarTurtle aimed to spread its wings when the time was right.

Lesotho, Mozambique and Zimbabwe are countries Van der Walt wants to expand into.

“At the same time, we don’t want to lose South Africa as a market,” he said.

Scientists at Heriot-Watt University are tackling the challenge of producing hydrogen from sunlight, an undertaking traditionally beset by high cost and low efficiency.

Hydrogen has a critical role to play in the UK’s energy future, with demand set to reach up to 860 terawatts (TWh) per year by 2050. Currently, the UK can only produce around 27 TWh of hydrogen power per year.

Converting sunlight to hydrogen is one of the most attractive approaches to meeting the growing demand for hydrogen in the UK, an approach that is said to be ‘clean’ and carbon-neutral.

Dr Jin Xuan, assistant professor of mechanical engineering, and associate director of the Research Centre for Carbon Solutions at Heriot-Watt University has been working with colleagues from Yale, the City University of Hong Kong and the East China University of Science and Technology. They are developing a new system to produce hydrogen from solar energy using a technique known as photoelectrochemical (PEC) water splitting. The technique uses solar energy to split the hydrogen and oxygen in water, and collect the hydrogen as a renewable energy source.

Until now, a minimum supply of 1.23 electron volts (eV) was required to split the water, and only small part of sunlight, the UV range, could be used, meaning the rest of the spectrum’s energy was wasted.

The system uses solar energy to split the hydrogen and oxygen in water, and collect the hydrogen as a renewable energy source.

Dr Xuan’s team has lowered the energy requirements of PEC water splitting to 0.35 eV, by developing a pH-differential design. By changing the pH of each electrode individually, the scientists change the whole thermodynamics of the process, meaning a wider spectrum of sunlight and much cheaper materials can be used.

The innovative microsystem generates unique microfluidic patterns to accommodate the pH differential, and acid and alkaline electrolytes can coexist in a single cell.

The new system will reduce the cost of PEC water splitting by around two thirds, and increase the solar to fuel efficiency by up to 20 percent.

“The main barrier to solar hydrogen production in the UK, and globally, is its high cost – it costs twice as much to produce as energy from wind and biomass.

“Our system will use cheap, widely available materials that mean the technology can be easily scaled up to meet the growing demand for hydrogen fuel.

“We have already proved that this system has potential. We’ve applied a similar design strategy in a number of energy devices, such as fuel cells and batteries.”

Hannah Smith, senior policy manager at Scottish Renewables, said: “Innovative projects like these show just how versatile our renewable energy resources can be. Renewable-fuelled green hydrogen can be used to store and transport electricity, to heat our homes and to fuel vehicles, making it a useful tool as we work to decarbonise our energy system.

“At this time of fundamental change in our energy sector, innovation becomes all the more important. Continued support for research and development is critical if these technologies are to reach commercialisation and deliver real impact across our energy system.”

Dr Xuan’s project was funded by the Engineering and Physical Sciences Research Council, and is conducted in partnership with Yale’s Energy Sciences Institute, the City University of Hong Kong and East China University of Science and Technology.

The dream of the Rashtriya Ispat Nigam Limited, the corporate entity of the Visakhapatnam Steel Plant to extract iron ore from mines owned by the Orissa Minerals Development Company (OMDC) after picking up majority stake in it, has been dashed with the Odisha government issuing separate notices why the mining leases should not be cancelled.

The reason for the ultimatum is the failure to pay compensation as per the Supreme Court orders within the stipulated time.

The OMDC became a holding company of the RINL after the navratna company invested ₹361 crore in the Eastern Investments Ltd (EIL) in 2010. The OMDC and the EIL are part of the Bird Group of Companies. The RINL, which is deprived of captive mines, had pinned a lot of hopes to source part of its iron ore requirement from the OMDC mines in Odisha.

Deadline

In separate notices (copies which are with The Hindu), B.K. Dehury, Additional Secretary to Government, Odisham in circulars 2567 and 2570 dated April 4, a 60-day deadline was set to pay the compensation and other dues failing which the government threatened to terminate the leases and forfeit the performance security.

The Supreme Court in its judgment dated August 2, 2017 in writ petition No. 114/2014 directed that compensation under Section 21 (5) of the MMDR Act should be paid by December 31, 2017. Subsequently, the Odisha government issued demand notices for production of minerals without lawful authority namely without/in excess for the environmental clearance and the amount before the deadline.

According to notice No. 2567, demand notice for payment of ₹377.75 crore was sent on December 13, 2017 and in response, the OMDC paid ₹10.56 crore on December 29, 2017.

In the same circular it was stated that for the lease of the Bhadrasahi iron and manganese mines in over 998.70 hectares, the Central Empowered Committee of Supreme Court, the OMDC in addition to the compensation, was supposed to deliver, after proper stacking, a stock of 3,27,866 MT of iron ore assessed as un-disposed by February 28, 2018 together with interest calculated at 14%.

The government said the apex court had directed it to take coercive steps to recover the unpaid dues.

Sources said the OMDC had reserves of 200 million tonnes of iron ore and 50 million tonnes of manganese dioxide in a 20-km radius in the Joda block of Keonjhar district of Odisha.

Steel Workers Federation of India general secretary and Keonjhar Mining Workers’ Union general secretary (OMDC recognised union) Indramani Behera said the Supreme Court imposed penalty for violation of environmental laws and indulging illegal mining against the OMDC and other lease-holders.

Penalty

Disclosing that the OMDC had to pay penalty of ₹1,470 crore and 14% penalty for delay in payment, he said stalemate was expected to continue with bleak chances for the RINL to undertake mining in Odisha. The OMDC has four direct and 250 indirect employees.