随着今年夏季欧洲的热浪肆虐，美国一家电池公司的员工注意到需求有所上升。
As heatwaves scorched Europe this summer, workers at a US battery company noticed an uptick in demand.
位于圣地亚哥的Unigrid为家庭销售一款九千瓦时的电池。酷热的欧洲房主显然在寻找在电网供电价格较低时存储电能的方法。这样他们就能在一天中最炎热的时候，使用电池更便宜地运行空调。
San Diego-based Unigrid sells a nine kilowatt hour battery for people's homes. Sweltering European homeowners were apparently looking for ways of storing power when it was available from the grid at lower rates. They could then run air conditioners more cheaply, off the battery, during the worst heat of the day.
“我们收到了来自西班牙、法国、德国、荷兰的订单，”联合创始人兼首席执行官达伦·谭说。“我们已经发出了前100台，并且[expect to ship]在年底前发货1,000台。” Unigrid的电池是一项新兴技术——它是钠离子电池，而非锂离子电池。钠离子电池让能源存储专家兴奋，因为它们最终可能比锂离子电池更便宜地建造和运营。
"We have requests coming from Spain, France, Germany, The Netherlands," says Darren Tan, co-founder and chief executive. "We've shipped the first 100 units and [expect to ship] 1,000 before the end of the year." Unigrid's battery is an emerging technology – it's a sodium ion, rather than lithium ion device. Sodium ion batteries have got energy storage experts excited because they could end up much cheaper to build and operate than lithium ion.
它们可能更不易起火，并且在更宽的温度范围内工作，甚至可降至-40℃，external。
They're potentially less likely to catch fire and should also work in a wider range of temperatures, even down to lows of minus 40C, external.
但关于什么构成最佳且最安全的钠离子电池设计仍存在争议。此外，近年来在该领域工作的多家外部美国公司都陷入困境，external。
But there's a debate over what constitutes the best, and safest, sodium ion battery design. Plus, more than one, external US company working in this space has floundered in recent years, external.
目前中国在钠离子电池制造方面领先全球，因此美国竞争者必须努力追赶。
China leads the world in sodium ion battery manufacturing at present so US competitors are going to have to work hard to keep up.
等待的奖赏是可能在美国制造、使用100%美国采购材料的电池。这与锂离子电池不同，后者在材料、外部供应链以及制造方面都由中国主导。
The prize that awaits is the possibility of batteries made in the US with 100% US-sourced materials. This is unlike lithium ion batteries, where China dominates the materials, external supply chain as well as manufacturing.
对谭来说，中国帮助他的公司进入市场。Unigrid电池目前使用的是在中国制造的钠离子电芯，而非在美国制造。“我们可以来回切换，选择我们想使用的电池，”谭解释说，未来他的公司可能会从美国采购电芯——尽管这些电芯可能会有不同的成本。
For Tan, China has helped his company get to market. The Unigrid battery currently uses sodium ion cells made there, rather than in the US. "We can switch back and forth and choose what battery we want to work with," says Tan, explaining that, in future, his firm might source cells from the US – though these may come at a different cost.
还有一个考虑因素。Unigrid 的电池在其阴极中含有三价铬。在电池中，电子从阴极流向阳极，外部充电时是这种方向，放电或提供电力时则相反。
There's another consideration. Unigrid's battery contains chromium-3 in its cathode. In a battery, electrons flow from cathode to anode, external when charging and in the opposite direction when discharging or providing power.
剑桥大学的克莱尔·格雷女爵教授（Prof Dame Clare Grey），她是电池公司 Nyobolt 的联合创始人，指出在某些条件下，三价铬可能转化为六价铬，这是一种有毒的致癌物。她对 BBC 说：“如果你打算使用钠……并且想要保证安全，那么就不要在其中加入可能引发红旗的元素。”
Prof Dame Clare Grey at the University of Cambridge, who is co-founder of battery firm Nyobolt, points out that under certain conditions chromium-3 may form chromium-6, a toxic, cancer-causing material., external "If you're going to go for sodium […] and you're going to sell safety, then don't start putting elements in that are going to raise red flags," she tells the BBC.
华威大学沃里克制造集团的伊凡娜·哈萨（Ivana Hasa）与 Unigrid 没有任何关联，她同意在极高的充电状态下，三价铬可能形成六价铬，但她表示这可以通过控制电池内的电压来减轻。“关于电池化学的安全测试结果非常有前景，”她对 Unigrid 的技术评价道。
Ivana Hasa, at the Warwick Manufacturing Group, University of Warwick, who has no connection to Unigrid, agrees that it is possible for chromium-3 to form chromium-6 at very high states of charge, though she says this can be mitigated by how voltage is controlled within the battery. "Safety tests reported on the cell chemistry are very promising," she says of Unigrid's tech.
坦（Tan）表示对电池材料毒性的担忧“被夸大了”，并强调 Unigrid 的电池已通过欧洲市场的认证和安全测试，并正在为美国市场进行类似评估。
Tan says concerns around toxicity of the battery's materials are "overblown" and emphasises that Unigrid's battery has passed certification and safety tests for sale in Europe and is currently undergoing such evaluations for the US market.
他表示第三方测试未能让电池产生六价铬。“我们非常努力地尝试制造它，尽可能多地过充……但未能产生六价铬。”阴极材料的选择，或者电解液（分隔阴极和阳极）的配方，都是影响钠离子电池性能和寿命的关键细节。一些制造商不使用铬作为阴极，而是采用硬碳，或者使用钠铁磷酸二磷酸盐（NFPP）。
Third-party tests have not been able to get the battery to form chromium-6, he says. "We've tried very hard to try and produce it, we've overcharged it as much as we can... We were unsuccessful in generating chromium-6." The choice of cathode material, or how the electrolyte – which separates cathode and anode – is formulated are key details influencing the performance and longevity of sodium ion batteries. Some manufacturers are not using chromium for their cathode but hard carbon instead, or sodium iron phosphate pyrophosphate (NFPP).
普遍而言，过去几年里人们对钠离子电池可靠性的信心有所提升，格雷女爵教授表示，这意味着它们现在正逐步进入电网储能应用。
In general, confidence around sodium ion batteries' reliability has increased during the last few years, says Prof Dame Grey, meaning they are now finding their way into grid storage applications.
去年12月，LFP电池（一种相对便宜的锂离子电池）的售价为每千瓦时81美元；而Unigrid公司的钠离子电池价格约为每千瓦时100美元。
Last December, LFP batteries – a relatively cheap form of lithium ion battery – were trading at $81 per kilowatt hour, external (kWh) whereas Unigrid's sodium ion battery pricing is roughly $100 kWh, external.
一些接受BBC采访的公司表示，钠离子电池的价格未来有可能降至每千瓦时30美元左右，但分析师认为实现这一目标还需要数年时间。
Some companies that spoke to the BBC suggested sodium ion might reach as low as $30 per kWh but analysts say significantly lower costs could be many years away, external.
钠离子电池的能量密度低于锂离子电池，因此为了提供相同的电量，它们需要体积更大、重量更重。不过近年来，钠离子电池的技术一直在进步。不过即便如此，钠离子电池仍不太可能被应用于智能手机等对电池体积要求严格、能耗较高的设备中；人们预计钠离子电池将在大型储能系统中发挥更重要的作用。
Sodium ion batteries are also not as energy dense as lithium ion batteries, meaning they must be slightly bigger and heavier in order to provide the same amount of power. The technology has been improving, external on this front in recent years but, even so, you're not likely to see sodium ion cells in small, energy hungry devices such as smartphones. Larger energy storage solutions are where most people expect sodium ion to dominate.
“我们认为钠离子电池将在市场上占据80%的份额，”总部位于西雅图的Emerald Battery Labs公司的联合创始人兼首席执行官David Bell说道。
"We think sodium ion […] is going to make up 80% of the market," says David Bell, co-founder and chief executive of Seattle-based Emerald Battery Labs.
Bell拒绝透露该公司正在研发的电池技术的具体细节，但他表示，Emerald Battery Labs目前仍在使用从中国进口的钠离子电池来生产他们的产品——这些12伏特的辅助电池目前正供应给美国的某些商业车队。
Bell declined to share details of the battery design his firm is working on, though he says Emerald too is currently relying on China-sourced sodium ion cells as they develop their initial product: 12 volt auxiliary batteries for vehicles, currently supplied to unnamed commercial fleets in the US.
“我们分析了市场后发现：‘目前还没有人试图进入这个领域，那么我们就来尝试吧！’”Bell说道。该公司接下来的目标是开发适用于美国本土生产的钠离子电池的新阳极材料。
"We took a look at the market and said 'Hey, no-one's trying to attack this space, let's have Emerald Battery Labs attack it'," says Bell. The firm's next goal is to develop new anodes for US-produced sodium ion cells.
另一家总部位于加利福尼亚州和科罗拉多州的公司Peak Energy在6月宣布与通用汽车（GM）建立了合作关系，双方计划共同建立钠离子电池的本土供应链，以实现大规模的电力存储应用。
Another company, Peak Energy, based in California and Colorado, announced a partnership with General Motors (GM) in June. The pair aim to develop a US supply chain for sodium ion batteries, in order to enable large-scale energy storage for electricity grids.
Peak Energy目前仍依赖中国采购的电芯用于首批装置，但希望帮助通用汽车在密歇根州建立美国本土生产设施，预计在2028年底前完成，Peak Energy的总裁兼联合创始人Cameron Dales表示。‘中国在钠离子电池方面并没有不可逾越的领先优势，’他补充道。
Peak Energy is also, at present, relying on China-sourced cells for its first installations, but hopes to help GM launch a US-based production facility in Michigan "by the end of 2028", says Cameron Dales, president and co-founder. "China does not have an insurmountable lead in sodium ion batteries," he says.
美国公司认为自己能竞争的一个原因是数据中心带来的电力需求激增，这些中心正在推动美国温室气体排放的上升。数据中心驱动的需求在全球其他地区也在上升，包括英国。
One reason US companies feel they can compete is because of the electricity demand boom from data centres, which are contributing to rising greenhouse gas emissions in the US. Data centre-driven demand is also rising in other places around the world, including the UK.
总部位于俄勒冈州的ESS Tech首席执行官Drew Buckley称这是一个‘机会’。他指出，钠离子电池可以帮助将可再生能源输送到数据中心，而这些电池的运行成本应低于锂离子替代品，因为它们不需要太多冷却。
This is an "opportunity" says Drew Buckley, chief executive at ESS Tech, headquartered in Oregon. He points out that sodium ion batteries could help distribute renewable energy to data centres. And those batteries should be cheaper to run than lithium ion alternatives, since they are not expected to require as much cooling.
ESS Tech正与另一家美国公司Alsym合作，后者计划到2027年运送数百兆瓦时的钠离子电池——均在美国制造。
ESS Tech is working with Alsym, another US firm that is planning to ship "hundreds" of megawatt hours' worth of sodium ion batteries – made in the US – by 2027.
Hasa表示，企业要实现钠离子电池的大规模生产将是‘具有挑战性的’。她还指出，虽然这种电池常被宣传为比锂离子更安全，但并非没有火灾风险。
Hasa says that it will be "challenging" for companies to establish mass production of sodium ion batteries. And she also notes that, while this type of battery is often touted as much safer than lithium ion, they do not come with zero fire risk.
但如果有公司能在这一领域取得成功，她补充说，这将为新的战略选择打开可能——帮助避免可再生电力浪费，并有可能保持能源成本低廉。‘我坚信这项技术，’Hasa说。
But if any firms can succeed in this space, they could enable new strategic choices, she adds – helping to avoid wastage of renewable electricity and potentially keeping energy costs low. "I'm a strong believer in the technology," says Hasa.