What happened to the Million Mile Battery?

Welcome back everyone, I'm Jordan Geisigee and this is The Limiting Factor. Nearly five years ago now, Tesla's Battery Research Partner, Professor Jeff Donne, published a research paper that claimed it was now possible to build a high-energy-density EV battery pack with off-the-shelf materials that would last up to a million miles in real-world conditions. I followed up on that research in my own videos and confirmed that indeed, the technology was ready for commercialization. And as a result, I expected that within a couple of years, Tesla would start using million-mile batteries in their vehicles. However, five years later, the batteries in Tesla's vehicles last three to four hundred thousand miles instead of a million, so the question is, what happened to the million-mile battery?

欢迎回来，大家好，我是Jordan Geisigee，这里是The Limiting Factor。大约五年前，特斯拉的电池研究合作伙伴Jeff Donne教授发表了一篇科研论文，声称现在可以用现成的材料制造出一种高能量密度的电动车电池组，该电池组在实际使用中可以持续行驶一百万英里。我在自己的视频中跟进了这项研究，并确认该技术确实已准备好商业化。因此，我原本预计在几年内，特斯拉会开始在其汽车中使用百万英里电池。然而，五年过去了，特斯拉车辆的电池寿命仍为三到四十万英里，而不是一百万英里。那么问题来了，百万英里电池怎么了？

Today, I'm going to walk you through the answer to that by looking at it from a technical perspective, by looking at comments from the team at Tesla, and by looking at the broader competitive landscape. In short, battery makers appear to be prioritizing specs like cost, charging speed, and supply chain security over cycle life, and there are better options such as LFP batteries for use cases that require high cycle life. Before we begin, a special thanks to my Patreon supporters, YouTube members, and Twitter subscribers, as well as RebellionAir.com. They specialize in helping investors manage concentrated positions. RebellionAir can help with covered calls, risk management, and creating a money master plan from your financial first principles.

今天，我将从技术角度探讨这个问题，并结合特斯拉团队的评论和更广泛的竞争环境，带您找到答案。简而言之，电池制造商似乎更注重成本、充电速度和供应链安全等参数，而非循环寿命。对于需要高循环寿命的使用场景，LFP电池是更好的选择。开始之前，特别感谢我的Patreon支持者、YouTube会员和Twitter订阅者，以及RebellionAir.com。他们专注于帮助投资者管理集中头寸，提供覆盖看涨期权、风险管理以及根据您的财务基本原则制定财务计划的帮助。

Let's start by looking at what the million-mile battery actually is. In 2019, Jeff Don published a paper showing that by using the best materials on the market, nickel-based lithium-ion batteries are capable of achieving very high cycle lives. That is, the number of times a battery cell can be charged and discharged before it fails. Typically, at that time, it was considered a great result if a nickel-based lithium-ion battery lasted around a thousand cycles, and what Jeff Don was able to show in his research was that could easily be pushed to four to five thousand cycles with the right materials. Four to five thousand cycles in a vehicle with 250 miles of range would mean an EV battery that would last a million miles, which is of course how the million-mile battery got its name.

让我们先来看一下百万英里电池到底是什么。2019年，杰夫·唐发表了一篇论文，展示了通过使用市场上最好的材料，镍基锂离子电池可以达到非常高的循环寿命。也就是说，电池在失效前可以充放电的次数。当时，一块镍基锂离子电池如果能持续大约一千次循环就被认为是很好的结果。而杰夫·唐通过他的研究表明，使用合适的材料可以轻松地将循环次数提高到四千到五千次。在拥有250英里续航能力的车辆中，这意味着电动车的电池可以持续使用一百万英里，这也就是百万英里电池名字的由来。

So how did Jeff Don's lab increase the cycle life by more than four to five times? There were three key materials involved. The first was single-crystal cathode material. Generally, lithium-ion batteries use polycrystal cathode particles, where hundreds or thousands of small primary crystals form a large secondary particle. That causes issues with cycle life because when a battery charges and discharges, the primary crystals expand and contract against each other, crack the secondary particle, and react with the electrolyte, which reduces cycle life. With a single-crystal cathode particle, the crystals aren't part of a larger conglomerate, and are free to expand and contract without grinding against other crystals, and therefore don't degrade as quickly.

那么，杰夫·唐的实验室是如何将电池的循环寿命提高到四到五倍的呢？这里涉及到三种关键材料。第一种是单晶正极材料。通常，锂离子电池使用的是多晶正极颗粒，这种颗粒由数百或数千个小晶体组成一个大的二次颗粒。这种结构在电池充放电过程中会出现问题，因为小晶体之间相互膨胀和收缩，会导致二次颗粒发生裂纹，并与电解液发生反应，从而降低循环寿命。而单晶正极颗粒的晶体不是大颗粒的一部分，它们可以自由地膨胀和收缩，而不会与其他晶体摩擦，因此不会那么快地劣化。

The second material was artificial graphite, which in my view was helpful but not critical to the high cycle life achieved with the million-mile battery. Artificial, also known as synthetic graphite, which is made in factories, tends to offer longer cycle life than natural graphite that comes from mines. But that's not always the case. So for the purposes of this video, we can ignore the artificial graphite as a key requirement for the million-mile battery. The third material was electrolyte additives. When a battery is cycled for the first time, additives react with the surface of the anode to form a protective film, called a Solid Electrolyte Interface, or SEI. That SEI protects the anode from continuing to react with the lithium in the electrolyte, which the battery needs to charge and discharge, so the SEI increases the cycle life of the battery. Some additives create an SEI layer that's significantly better at protecting the anode from those reactions, which makes the battery last even longer.

第二种材料是人造石墨，在我看来，它对实现百万英里电池的高循环寿命有帮助，但并不是关键。人造石墨，也称为合成石墨，是在工厂中制造的，通常比来自矿山的天然石墨提供更长的循环寿命，但这并不总是如此。所以就本视频而言，我们可以忽略将人造石墨作为百万英里电池的关键要求。第三种材料是电解质添加剂。当电池第一次循环使用时，添加剂会与阳极表面发生反应，形成一种保护膜，称为固态电解质界面（SEI）。这种SEI可保护阳极不再与电解质中的锂发生反应，这对电池的充放电是必要的，因此SEI增加了电池的循环寿命。一些添加剂可以形成的SEI层在保护阳极免受这些反应方面更有效，这使得电池寿命更长。

That occurs at very low percentages as a proportion of the electrolyte, such as give or take, around 1% of the weight of the electrolyte. What all this means is that, overall, making a million-mile battery at a conceptual level is pretty straightforward. So why hasn't it happened yet? Why are the batteries in a Tesla vehicle lasting around 3,000 to 400,000 miles, rather than 2 to 3 times that? Let's start with the cathode. My understanding is that single-crystal cathode material tends to be about 5% more expensive than polycrystal cathode material, because, for example, its production process can require two heating steps instead of one, which adds cost. However, with enough production scale, I suspect the cost of single-crystal cathode material would probably reach close to cost parity with polycrystal cathode material. That's because both poly and single-crystal cathode use the same raw material inputs for production. And the learning curve involved with scaling always drives product costs towards materials cost.

这种情况发生在电解质中占比非常低，例如大约占电解质重量的1%左右。总的来说，这意味着从概念上来说，制造百万英里电池其实并不复杂。那么，为什么它还没有成为现实呢？为什么特斯拉汽车的电池寿命大约是30万到40万英里，而不是2到3倍呢？让我们从正极材料开始讨论。我的理解是，单晶正极材料往往比多晶正极材料贵大约5%，因为它的生产过程可能需要两个加热步骤而不是一个，这增加了成本。然而，在达到足够的生产规模后，我推测单晶正极材料的成本可能会接近与多晶正极材料的成本平衡。这是因为单晶和多晶正极材料在生产时都使用相同的原材料。而随着规模化的学习曲线，产品成本总是趋向于接近材料成本。

The next issue with the cathode is more of a first-principal's physics problem. If you look closely at this image, you can see that the single-crystal cathode particles are only about 1 to 2 microns across. That's as opposed to a polycrystal cathode particle, which is about an order of magnitude larger. The smaller particle size of single-crystal cathode creates two issues. First, in order for electricity to conduct between the cathode particles and have low resistance, it has to be coated with highly conductive carbon-black powder. Smaller particles means a higher ratio of surface area to volume, which means higher costs and lower energy density due to a higher proportion of inactive material. I do expect that could be somewhat resolved with single-walled carbon nanotubes, which are much more conductive than carbon-black and getting cheaper. But there would still be a fundamental cost disadvantage for single-crystal cathode particles compared to larger polycrystal cathode particles.

下一个关于正极的问题更像是一个物理上的基本原理问题。如果你仔细观察这张图片，你会发现单晶正极粒子的直径只有1到2微米。相比之下，多晶正极粒子的直径要大一个数量级。单晶正极的较小粒径带来了两个问题。首先，为了让电流在正极粒子之间顺利传导并保持低阻力，需要用高导电性的碳黑粉末进行涂层。较小的粒子意味着表面积与体积的比例更高，这意味着更高的成本和由于更高比例的非活性材料而导致的更低能量密度。我预计这一问题可能通过单壁碳纳米管得到一定程度的解决，因为它们比碳黑导电性更好且价格越来越便宜。但即便如此，与较大的多晶正极颗粒相比，单晶正极颗粒在成本方面仍存在一个基本的劣势。

Second, which is speculation on my part, polycrystal cathode particles are somewhat porous, which allows them to become saturated with liquid electrolyte. That creates pathways for lithium ions deep into the cathode particle. So even a large particle allows for a relatively low resistance flow of ions into and out of the cathode crystals at the center of the particle. With a single-crystal cathode particle, it's a monolithic crystal. And so even if it was possible to grow the crystals larger, the charge and discharge rate might be slower because the lithium ions might encounter more resistance when trying to reach the core of the crystal. That's because, among other things, the cathode is made of solid two-dimensional sheets rather than a flowable three-dimensional liquid. If that's all correct, I don't know of an engineering solution to that because the ionic resistance of larger crystals would very much be a first-principles physics problem. If I'm incorrect here and you have some insights on crystal size and ionic resistance for poly and single-crystal cathodes, let me know in the comments below.

其次，这只是我的推测：多晶阴极颗粒稍微有点多孔，这使得它们能够吸收液态电解质。在这样的情况下，锂离子可以通过这些孔隙深入到阴极颗粒内部。这意味着即便是较大的颗粒也能够相对低阻力地让离子进出颗粒中心的阴极晶体。而单晶阴极颗粒则是一个整体的单一晶体，即使可能把晶体做大，由于锂离子在到达晶体核心时可能会遇到更大的阻力，充电和放电速率反而可能变慢。这部分是因为阴极由坚固的二维片层构成，而不是能够流动的三维液体。如果我的推论正确，那么我不认为有工程上的解决方案因为较大晶体的离子阻力是个根本性的物理问题。如果我有误并且您对多晶和单晶阴极的晶体大小及离子阻力有见解，请在下方评论区告诉我。

Now that we've covered the challenges with the cathode for the million-mile battery, let's take a look at the electrolyte. Both Jeff Don and Tesla employees have said that some of the additives that can dramatically increase the cycle life of batteries are IP-locked or intellectual property-locked. That means there are players in the market that have a monopoly on those additives, which in turn means that if a battery manufacturer runs into a supply issue with those additives, there's no fallback source in the battery supply chain. And of course, because additives can dramatically improve cycle life and the suppliers have a monopoly on them, they tend to charge large premiums for the additives. In short, high-performing additives are high risk and high cost, and most battery manufacturers aren't willing to accept the additional risk in their supply chain nor the additional cost.

现在我们已经讨论了百万英里电池阴极的问题，接下来看看电解液。Jeff Don和特斯拉的员工都表示，一些可以显著提高电池循环寿命的添加剂被视为知识产权保护的技术。这意味着市场上有一些参与者垄断了这些添加剂，这也就是说如果电池制造商在这些添加剂的供应上遇到问题，电池供应链中就没有备用来源。由于这些添加剂能够显著提高电池的循环寿命，而供应商对这些添加剂进行垄断，他们通常会昂贵地定价。简而言之，高性能的添加剂既高风险又高成本，大多数电池制造商不愿意在他们的供应链中承担增加的风险和成本。

That's because currently, five years on from the million-mile battery paper, commercially available nickel-based lithium-ion batteries are usually achieving at least 1,200 cycles. On a vehicle with 300 miles of range, which is now common, after factoring in capacity loss, that's roughly 300,000 miles over the life of the vehicle, which is more than enough for most vehicle buyers. That makes higher cycle life low priority.

这是因为在最初有关百万英里电池的论文发表五年后，目前市面上可买到的镍基锂离子电池通常能够达到至少1200次循环。在一辆续航里程为300英里的汽车上（现在很常见），即使考虑到电池容量的损失，这也大致可以达到汽车整个使用寿命中的30万英里，这对大多数购买者来说已经足够用了。因此，提高循环寿命的优先级就显得不是那么重要。

That's as opposed to cost, which is almost always one of the top priorities for vehicle buyers. With that said, as I pointed out in my PDO patent video, Tesla and Jeff Don still do appear to be developing additives that improve cycle life. That is, they're trying to commercialize their own in-house alternatives to the IP-locked additives. If those additives can be produced at no additional cost or lower cost than the IP-locked additives, then there's no reason not to use them in battery cells. There's no way to know how that commercialization process is going, but it's clearly a goal that they have their site set on. So for now, it's a matter of wait and see.

与成本不同，成本几乎总是车辆购买者最优先考虑的因素之一。话虽如此，正如我在PDO专利视频中指出的，特斯拉和Jeff Don似乎仍在开发能够提高电池循环寿命的添加剂。也就是说，他们正在尝试将自己研发的添加剂商业化，以替代那些受知识产权保护的添加剂。如果这些添加剂的生产成本与或低于现有专利保护的添加剂，就没有理由不在电池中使用它们。目前还不知道这一商业化进程进展如何，但显然这是他们的目标。所以现在只能静观其变。

If they do succeed, it would open the door to dramatic improvements in cycle life for Tesla batteries. How much of an improvement would be a product level question based on cost and performance trade-offs, but it appears that a doubling of battery life would easily be on the table. But, as with all things batteries, I'm not holding my breath, and overall, I expect incremental increases in cycle life over time. On that note, some people might point out that although using a more expensive single crystal cathode and IP-locked additives might cost more from a cost per kilowatt hour perspective, it would result in much higher cycle life, meaning more value in terms of cost per kilowatt hour per cycle. That's definitely true. But again, it comes down to the preferences of the average consumer, and cost per kilowatt hour per cycle isn't a factor. As long as their EV lasts as long as an internal combustion vehicle, they're happy, and their main concern is factors like cost and charge rate, so those specs get disproportionate attention by automakers.

如果他们成功了，这将为特斯拉电池的循环寿命带来显著的提升。具体能提升多少需要在产品层面上考虑成本和性能的权衡，但看起来电池寿命翻倍是可以实现的。不过，正如电池领域的其他事情一样，我不会急于期待，而是整体上期望循环寿命在时间的推移中逐步提高。有些人可能会指出，尽管使用更昂贵的单晶正极材料和知识产权受保护的添加剂可能从每千瓦时的成本角度来看更贵，但这会大大提高循环寿命，也就是每个循环的千瓦时成本更有价值。这确实是事实。不过，这最终还是要看普通消费者的偏好，每个循环的千瓦时成本并不是一个关键因素。只要他们的电动车使用寿命能和内燃机车一样长，他们就很满意，他们主要关心的是成本和充电速率这些因素，所以这些规格得到了汽车制造商的不成比例的关注。

Interestingly, the same dynamic that plays out for cycle life also plays out for charging speed. Tesla could increase the charging speed of their vehicles, but it would come at the expense of specs like cost and cycle life. Given that charging speed of Tesla vehicles is generally competitive, that's not a worthwhile trade-off. I'll cover the options for increasing the charge rate of EVs more thoroughly when I do a video on CATL's shunching battery. Much like the million mile battery showcased how using a combination of the best technologies on the market could improve cycle life. My view is that shunching is doing the same for charging speed.

有趣的是，电池循环寿命的动态变化和充电速度之间也存在类似的关系。特斯拉可以提高他们车辆的充电速度，但这会损害成本和循环寿命等参数。考虑到特斯拉车辆的充电速度通常具有竞争力，这种权衡并不值得。我会在一段关于CATL的"瞬充电池"的视频中更详细地讲解提高电动车充电速度的选项。就像"百万英里电池"展示了如何利用市场上最好的技术组合来提高循环寿命一样，我认为"瞬充"对充电速度的提升有类似的作用。

Getting back on track on the topic of cost per kilowatt hour per cycle, what about grid storage? Isn't cost per kilowatt hour per cycle the key metric for that use case? Yes, it is the key metric, but in my view, the grid storage market is going to be cornered by LFP batteries, and then potentially down the road by sodium ion batteries. That's because LFP batteries are much cheaper than nickel-based lithium ion batteries, and there are cells on the market now that offer up to 12,000 cycles of use before reaching end of life. LFP batteries are lower energy density than high nickel batteries, but that's not the primary requirement for grid storage like it is for EVs.

回到每千瓦时每周期成本这个话题，那么对于电网储能呢？这种情况下，每千瓦时每周期的成本不是关键指标吗？是的，这是关键指标。但在我看来，电网储能市场将被磷酸铁锂（LFP）电池主导，将来可能还有钠离子电池。这是因为LFP电池比镍基锂离子电池便宜得多，目前市场上已经有电池可以在生命周期结束前提供多达12,000个循环使用。LFP电池的能量密度比高镍电池低，但对电网储能而言，这并不是像对于电动汽车那样的首要要求。

So overall, even if Tesla was able to radically increase the cycle life of nickel-based lithium ion batteries without increasing their price, they can't compete with LFP for grid storage because LFP batteries cost more than 20% less, they're easier to scale because they use more abundant materials and have fundamentally better cycle life. If you'd like to know more about LFP batteries, watch my LFP Science video. In summary, the Million Mile Battery is one of the first things that I covered on this channel four years ago. At that time, I didn't see any showstoppers from a technology standpoint. However, the limiting factor for the adoption of a new technology can often be something mundane or unexpected. The Million Mile Battery is a good example of that.

总体来说，即使特斯拉能够在不提高价格的情况下，大幅增加其镍基锂离子电池的循环寿命，它们在电网储能方面也无法与LFP电池竞争。因为LFP电池的成本要低20%以上，而且它们使用更为丰富的材料，易于扩大生产，并且从根本上拥有更好的循环寿命。如果你想了解更多关于LFP电池的信息，可以观看我的LFP科学视频。总之，百万英里电池是我四年前在这个频道上首次讨论的话题之一。当时，从技术角度来看，我没有发现任何会阻碍其发展的因素。然而，新技术的推广瓶颈往往可能是一些平凡或意想不到的事情。百万英里电池就是一个很好的例子。

Although all the technology was there on the market five years ago to manufacture high nickel-million-mile batteries, there were three critical issues. First, the single crystal cathode would have traded a slight reduction in energy density and a slight increase in cost for a large increase in cycle life, but energy density and cost are far more important to consumers. Second, the electrolyte additives needed to make the Million Mile Battery work tend to be IP-locked, which makes them more expensive and more risky to build a supply chain around.

虽然在五年前，市场上已经具备了生产高镍百万英里电池所需的所有技术，但仍然存在三个关键问题。首先，单晶正极可以通过略微降低能量密度和略微增加成本来大幅延长电池寿命，但对于消费者来说，能量密度和成本更为重要。其次，使百万英里电池运作所需的电解质添加剂通常受到知识产权限制，这不仅使其更昂贵，而且增加了围绕它建立供应链的风险。

Third, since the Million Mile Battery paper was published, LFP batteries have gone from strength to strength. With lower costs, higher cycle life, greater scalability and availability, and other less talked-about factors like improved hardware and software controls to accommodate their flat voltage profile. What all that means is that in use cases where long cycle life is needed, LFP batteries are usually the best option. With all that said, I do expect the cycle life of nickel-based lithium-ion batteries to continue to increase over time as a result of Jeff Don's research into better electrolyte formulations, but the speed that happens will be dependent on when and if Tesla commercializes in-house additives and how nicely those additives play with electrolyte formulations that increase charging speed.

第三，自从“百万英里电池”的论文发表以来，磷酸铁锂（LFP）电池一直在不断发展壮大。它们具有更低的成本、更长的循环寿命、更大的可扩展性和可用性，以及其他不太被讨论的因素，比如为了适应其平稳的电压曲线而改进的硬件和软件控制。这些意味着在需要长循环寿命的使用场景中，LFP电池通常是最佳选择。尽管如此，我也预计由于Jeff Don对更好电解质配方的研究，镍基锂离子电池的循环寿命会随着时间的推移不断提高，但这将取决于特斯拉何时能够实现内部添加剂的商业化，以及这些添加剂与提高充电速度的电解质配方的兼容性如何。

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