法國(guó)納米材料公司NAWA Technologies打算對(duì)汽車(chē)行業(yè)使用的“混動(dòng)”一詞增添一層新涵義，它希望將基于碳納米技術(shù)的高效超級(jí)電容器與鋰離子電池結(jié)合起來(lái)，為大體積電動(dòng)汽車(chē)提供雙重電源。
NAWA聲稱(chēng)，這個(gè)名為超快碳電池（UltraFast Carbon Battery）的技術(shù)已進(jìn)入試投產(chǎn)階段，其功率和能源密度比現(xiàn)有的超級(jí)電容器高3-5倍。
NAWA表示，其長(zhǎng)期目標(biāo)是將混合超級(jí)電容器電池的充電速度和壽命提升至，甚至超過(guò)當(dāng)前（或更高級(jí)的）鋰離子電池。
公司CEO Ulrik Grape表示，基于公司的研發(fā)成果，他有充分理由相信一種徹底的儲(chǔ)能系統(tǒng)的量產(chǎn)可以解決目前的許多問(wèn)題，有助于改變公眾對(duì)電動(dòng)汽車(chē)電池功率的認(rèn)知。
“我們的超快碳電池的獨(dú)特之處在于我們自主研發(fā)的垂直排列特殊涂層納米管，該技術(shù)可以提升碳納米管或基礎(chǔ)電容器的能量密度，”Ulrik Grape告訴《汽車(chē)工程》雜志。
“我們能夠以超快的速度接收并釋放電荷，這個(gè)高功率技術(shù)可以幫助汽車(chē)行業(yè)實(shí)現(xiàn)越來(lái)越高的能源密度目標(biāo)。”Grape于2017年加入NAWA，此前他是加州固態(tài)鋰離子電池創(chuàng)業(yè)公司SEEO的管理人員，后者最近被博世收購(gòu)。
NAWA聲稱(chēng)，其新一代能量回收電池可“在幾秒內(nèi)充放電100萬(wàn)次循環(huán)”，非常適用于無(wú)人駕駛汽車(chē)，尤其是共享汽車(chē)。由于該電池是基于碳制作的，因此不會(huì)出現(xiàn)傳統(tǒng)儲(chǔ)能電池的各種高溫問(wèn)題。此外，它與氫燃料電池的技術(shù)也十分匹配。
回收制動(dòng)能量
NAWA是“用納米技術(shù)對(duì)抗全球變暖(NAno technology to fight against global WArming)”這句公司創(chuàng)立宗旨的關(guān)鍵字縮寫(xiě)，它是法國(guó)原子能與替代能源組織（CEA）的衍生企業(yè)，于2013年成立。其創(chuàng)立者堅(jiān)信可以將電池的儲(chǔ)能容量提升至現(xiàn)有電池的五倍，而這將在電動(dòng)汽車(chē)的發(fā)展中扮演重要角色。
NAWA電池的一個(gè)重要特征就是均勻涂覆聚合物的納米管。為什么納米管的垂直排列如此重要？Grape表示：“這樣做可以對(duì)電子和離子加以管束，使它們沿著整齊的路線(xiàn)，而非隨機(jī)的路線(xiàn)運(yùn)動(dòng)，就像是牙刷上排列整齊的刷毛一樣！”
超快碳電池能夠以極高的速度釋放電量（與傳統(tǒng)電池相比較，極小的電池可在幾秒或幾毫秒內(nèi)釋放，而且對(duì)溫度的依賴(lài)也更少），以滿(mǎn)足突然加速的要求。更為重要的是，這種功能還有助于充分回收制動(dòng)能量。Grape認(rèn)為汽車(chē)行業(yè)尚未對(duì)這一點(diǎn)給予足夠重視，但他表示OEM和供應(yīng)商對(duì)新技術(shù)的態(tài)度的確變得越來(lái)越開(kāi)放了。
“歐洲企業(yè)對(duì)我們的新電池表現(xiàn)出濃厚的興趣，”他表示。“在一個(gè)48V或容量更大的系統(tǒng)中，我們可以回收90%以上的制動(dòng)能量。”NAWA的研發(fā)工作包括一款電動(dòng)方程式汽車(chē)的混動(dòng)電池的模擬，該電池由鋰離子電池和NAWA的超級(jí)電容器組成。該項(xiàng)目看似有點(diǎn)跑題，但Grape認(rèn)為它非常重要。“我們研究了多場(chǎng)比賽的參數(shù)，發(fā)現(xiàn)在僅使用鋰離子電池的情況下，轉(zhuǎn)彎處的制動(dòng)能量回收率僅為20%左右”。
減重與成本
Grape認(rèn)為，借助超級(jí)電容器和鋰離子電池還能實(shí)現(xiàn)顯著的車(chē)身減重。“最初階段可以將車(chē)身重量從300公斤減至200公斤，之后再想減100公斤就必須對(duì)整個(gè)電氣系統(tǒng)進(jìn)行優(yōu)化了。但是目前我們的電容器容量還不及鋰離子電池，因此不能聲稱(chēng)可以取代它們。我們的系統(tǒng)可以和鋰離子電池聯(lián)合運(yùn)行。儲(chǔ)能是通過(guò)整個(gè)系統(tǒng)實(shí)現(xiàn)的，而不只是依靠我們的技術(shù)。”
還有一點(diǎn)重要的是，整個(gè)系統(tǒng)的使用壽命會(huì)比僅有鋰離子電池的系統(tǒng)更長(zhǎng)，因?yàn)槌?jí)電容器和鋰電池可以分工合作，前者擔(dān)任負(fù)重任務(wù)，后者負(fù)責(zé)自動(dòng)駕駛。
使用高效超級(jí)電容和能量回收技術(shù)有可能延長(zhǎng)汽車(chē)的行駛里程，但Grape對(duì)這個(gè)話(huà)題較為謹(jǐn)慎。
“根據(jù)我們和汽車(chē)行業(yè)對(duì)整個(gè)生產(chǎn)系統(tǒng)的討論，我們估計(jì)里程的延長(zhǎng)可高達(dá)40-50%，但目前說(shuō)這些還太早了，”他表示。
汽車(chē)行業(yè)中任何新技術(shù)的誕生都繞不開(kāi)成本話(huà)題。Grape認(rèn)為其電池的成本會(huì)比現(xiàn)有的超級(jí)電容器“低幾個(gè)數(shù)量級(jí)”，但具體數(shù)字還等待進(jìn)一步的確認(rèn)。
超快碳電池的核心技術(shù)和生產(chǎn)工藝與光伏電池“非常相似”，但是針對(duì)汽車(chē)應(yīng)用的大規(guī)模生產(chǎn)還需要投入全新的工藝。
光伏電池的生產(chǎn)工藝通常是在電池外部涂覆一層由幾十種粉末、添加劑和粘合劑組成的混合物，而NAWA的工藝則不同。它們首先注射一種包含大量碳原子的液體，然后將其汽化，使一層均勻、堅(jiān)固、柔軟的垂直排列納米管“地毯”自動(dòng)生長(zhǎng)。
NAWA的試投產(chǎn)在其位于法國(guó)普羅旺斯地區(qū)艾克斯的胡賽研發(fā)工廠(chǎng)進(jìn)行。第二批試投產(chǎn)線(xiàn)預(yù)計(jì)于2019年建設(shè)完畢并開(kāi)展生產(chǎn)。電池的最初應(yīng)用預(yù)計(jì)為動(dòng)力工具，接著會(huì)與汽車(chē)行業(yè)開(kāi)展合作，這也是汽車(chē)行業(yè)引進(jìn)新技術(shù)的慣常做法。Grape表示，公司計(jì)劃在未來(lái)4-5年內(nèi)實(shí)現(xiàn)首批汽車(chē)應(yīng)用，接著實(shí)現(xiàn)大規(guī)模量產(chǎn)。
NAWA的創(chuàng)始人兼首席運(yùn)營(yíng)官PascalBoulanger補(bǔ)充道：“最讓人激動(dòng)人心的是超級(jí)電容器的巨大潛力。通過(guò)超快碳電池，我們成功地將納米技術(shù)和最好的清潔技術(shù)結(jié)合了起來(lái)。”
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
這就是NAWA的新技術(shù)，目前正在該公司位于法國(guó)南部的工廠(chǎng)中開(kāi)展試生產(chǎn)。（圖片來(lái)源：NAWA）
