法国纳米材料公司NAWA Technologies打算对汽车行业使用的“混动”一词增添一层新涵义，它希望将基于碳纳米技术的高效超级电容器与锂离子电池结合起来，为大体积电动汽车提供双重电源。

NAWA声称，这个名为超快碳电池（UltraFast Carbon Battery）的技术已进入试投产阶段，其功率和能源密度比现有的超级电容器高3-5倍。

NAWA表示，其长期目标是将混合超级电容器电池的充电速度和寿命提升至，甚至超过当前（或更高级的）锂离子电池。

公司CEO Ulrik Grape表示，基于公司的研发成果，他有充分理由相信一种彻底的储能系统的量产可以解决目前的许多问题，有助于改变公众对电动汽车电池功率的认知。

“我们的超快碳电池的独特之处在于我们自主研发的垂直排列特殊涂层纳米管，该技术可以提升碳纳米管或基础电容器的能量密度，”Ulrik Grape告诉《汽车工程》杂志。
 

“我们能够以超快的速度接收并释放电荷，这个高功率技术可以帮助汽车行业实现越来越高的能源密度目标。”Grape于2017年加入NAWA，此前他是加州固态锂离子电池创业公司SEEO的管理人员，后者最近被博世收购。

NAWA声称，其新一代能量回收电池可“在几秒内充放电100万次循环”，非常适用于无人驾驶汽车，尤其是共享汽车。由于该电池是基于碳制作的，因此不会出现传统储能电池的各种高温问题。此外，它与氢燃料电池的技术也十分匹配。
 

回收制动能量
 

NAWA是“用纳米技术对抗全球变暖(NAno technology to fight against global WArming)”这句公司创立宗旨的关键字缩写，它是法国原子能与替代能源组织（CEA）的衍生企业，于2013年成立。其创立者坚信可以将电池的储能容量提升至现有电池的五倍，而这将在电动汽车的发展中扮演重要角色。

NAWA电池的一个重要特征就是均匀涂覆聚合物的纳米管。为什么纳米管的垂直排列如此重要？Grape表示：“这样做可以对电子和离子加以管束，使它们沿着整齐的路线，而非随机的路线运动，就像是牙刷上排列整齐的刷毛一样！”

超快碳电池能够以极高的速度释放电量（与传统电池相比较，极小的电池可在几秒或几毫秒内释放，而且对温度的依赖也更少），以满足突然加速的要求。更为重要的是，这种功能还有助于充分回收制动能量。Grape认为汽车行业尚未对这一点给予足够重视，但他表示OEM和供应商对新技术的态度的确变得越来越开放了。

“欧洲企业对我们的新电池表现出浓厚的兴趣，”他表示。“在一个48V或容量更大的系统中，我们可以回收90%以上的制动能量。”NAWA的研发工作包括一款电动方程式汽车的混动电池的模拟，该电池由锂离子电池和NAWA的超级电容器组成。该项目看似有点跑题，但Grape认为它非常重要。“我们研究了多场比赛的参数，发现在仅使用锂离子电池的情况下，转弯处的制动能量回收率仅为20%左右”。

减重与成本

Grape认为，借助超级电容器和锂离子电池还能实现显著的车身减重。“最初阶段可以将车身重量从300公斤减至200公斤，之后再想减100公斤就必须对整个电气系统进行优化了。但是目前我们的电容器容量还不及锂离子电池，因此不能声称可以取代它们。我们的系统可以和锂离子电池联合运行。储能是通过整个系统实现的，而不只是依靠我们的技术。”

还有一点重要的是，整个系统的使用寿命会比仅有锂离子电池的系统更长，因为超级电容器和锂电池可以分工合作，前者担任负重任务，后者负责自动驾驶。

使用高效超级电容和能量回收技术有可能延长汽车的行驶里程，但Grape对这个话题较为谨慎。

“根据我们和汽车行业对整个生产系统的讨论，我们估计里程的延长可高达40-50%，但目前说这些还太早了，”他表示。

汽车行业中任何新技术的诞生都绕不开成本话题。Grape认为其电池的成本会比现有的超级电容器“低几个数量级”，但具体数字还等待进一步的确认。

超快碳电池的核心技术和生产工艺与光伏电池“非常相似”，但是针对汽车应用的大规模生产还需要投入全新的工艺。

光伏电池的生产工艺通常是在电池外部涂覆一层由几十种粉末、添加剂和粘合剂组成的混合物，而NAWA的工艺则不同。它们首先注射一种包含大量碳原子的液体，然后将其汽化，使一层均匀、坚固、柔软的垂直排列纳米管“地毯”自动生长。

NAWA的试投产在其位于法国普罗旺斯地区艾克斯的胡赛研发工厂进行。第二批试投产线预计于2019年建设完毕并开展生产。电池的最初应用预计为动力工具，接着会与汽车行业开展合作，这也是汽车行业引进新技术的惯常做法。Grape表示，公司计划在未来4-5年内实现首批汽车应用，接着实现大规模量产。

NAWA的创始人兼首席运营官PascalBoulanger补充道：“最让人激动人心的是超级电容器的巨大潜力。通过超快碳电池，我们成功地将纳米技术和最好的清洁技术结合了起来。”

French nanomaterials specialist NAWA Technologies is aiming to bring a new dimension to the automotive industry’s use of the word “hybrid.” It is aiming to link high efficiency new technology carbon nano-based ultracapacitors with lithium-ion batteries, to create a dual energy source for high volume electric vehicles.
NAWA claims its Ultra Fast Carbon Battery technology now in pilot production, can deliver between three and five times higher power and energy density than existing ultracapacitors.

The company has stated that in the “long term” its technology will enable it to develop hybrid ultracapacitor cells with performance levels approaching or surpassing current (or even advanced) lithium batteries in terms of fast charging and lifecycle.

The result of its R&D work, said CEO Ulrik Grape, is confidence that high volume manufacture of a radical energy storage system will help overcome many of the frustrations that continue to dog the wholesale public acceptance of automotive electric motive power.

“The unique aspect of the technology of our Ultra Fast Carbon Battery is our successful development of vertically aligned specially coated nanotubes, allowing us to increase the energy density of the carbon nanotubes or basic capacitor," he told Automotive Engineering.

“We can accept the charge and release it exceptionally fast," he explained. "This is a high power technology that can assist the automotive sector’s requirement to achieve ever greater energy density.” Grape joined NAWA in 2017, having been part of the management team at California solid-state lithium-ion battery start-up SEEO, recently acquired by Bosch.

NAWA’s claim is that its new generation of energy-recouping batteries could be recharged “in seconds for up to a million cycles,” ideal for autonomous vehicles, notably shared cars. Carbon-based, the new Ultra Fast Battery configuration is said by the company not to suffer the thermal issues of conventional storage systems. It could also fit technologically with hydrogen fuel cells.

Regen braking benefits

NAWA (NAno technology to fight against global WArming) Technologies, a 2013 spin-out business from the French Atomic and Alternative Energies’ Organization (CEA), states that the battery is capable of storing up to five times more energy than existing capacitors, would play a key part in electrified vehicle development.

A significant aspect of the NAWA battery involves the use of the uniformly applied polymer coating of the nanotubes. But why is vertical alignment of nanotubes so important? Said Grape: “It’s about regimenting electrons and ions, smoothing their path instead of their taking a random route. It’s rather like the perfectly ordered bristles of a toothbrush!”

Benefits of the Ultra Fast Carbon Battery include the capability of very high speed delivery of a charge (compared to conventional batteries, typically in a few seconds or milliseconds for very small cell sizes and with less dependence on temperature) to meet sudden acceleration requirements. Also, and possibly more importantly, to harvest as much braking energy as possible. Grape believes the industry has not paid sufficient attention to this, although he accepts that OEMs and suppliers are becoming ever less conservative in adopting new technology.

“European companies in particular are showing strong interest in our new battery," he stated. "In a 48V or larger system we could perhaps recoup up to 90%-plus of available braking energy.”
NAWA development work has included the simulation of a Formula E hybrid battery featuring lithium-ion batteries and its own ultracapacitors. This may be regarded as the exotic end of the auto industry but Grape believes it is a relevant program. “We looked at performance on several race circuits and received information from drive cycles which showed only about 20% of energy recovery when braking for turns using only lithium-ion batteries,” he noted.

Mass reduction, cost

Grape believes very significant overall weight reduction could be achieved using the hybrid ultracapacitor and lithium-ion system. “Initially it could typically be reduced from 300 kg to 200 kg," he said. "Further savings of another 100 kg could be possible through optimization of the overall electrical system. But we are not storing as much energy as lithium-ion batteries and are not professing to replace them. Our system would work in conjunction with lithium-ion; storage would need to involve the performance of the whole system not just our technology."

Significantly, the overall system is expected to have a longer in-service life than stand-alone lithium-ion batteries, as the ultracapacitors handle the heavy loads and the lithium-ion address the autonomy.
Grape is cautious on the emotional subject of range enhancement potential via the use of its more efficient ultracapacitor technology and resultant energy harvesting.

“Depending on the outcome of discussions with the auto industry regarding all aspects of a production system, it could be as high as 40% to 50%, but it is too early to be specific,” he said.

Likely cost is inevitably the major issue when new technology looms on the automotive horizon. Grape sees this as being “orders of magnitude less" than that of super- or ultracapacitors currently available,” adding that precise figures are still to be refined.

Core technology and manufacture of the Ultra Fast Carbon Battery are claimed to be “very comparable” to those of the photovoltaic industry in general, although for application to high volume automotive production, a unique process would be applied.

Instead of coating a mixture of dozens of powders, additives and binders—very fragile when charging and discharging, NAWA's approach is different. A liquid containing a high content of carbon atoms is injected then vaporized, which allows the growth of a uniform, robust and flexible "carpet" of the vertically aligned nanotubes.

NAWA’s pilot production unit is at its French R&D facility at Rousset, Aix-en-Provence. The second generation of the pilot line is scheduled to be up and running in 2019. Initial applications are likely to be for power tools. The automotive qualification process— working together with the industry—is expected to follow. Grape said the aim is for initial production for automotive to begin in four to five years, then ramping up to high volumes.

NAWA founder and COO, Pascal Boulanger, added: “What is really exciting is the sheer potential of ultracapacitors. With the Ultra Fast Carbon Battery, we have combined the best nanotechnology with the best clean technology.”

Author: Stuart Birch
Source: SAE Automotive Engineering Magazine