Show HN: 打造一款由核衰变驱动的智能手机：动力工程
2 分•作者: joshuashelvin•3 个月前
过去二十年里制造的每一部智能手机都基于同一个假设：电池每天都需要充电一次。在开始计算之前，先思考一下：如果手机永远不需要插电，会发生什么变化？
这就是我正在构建的东西。电源是β伏特电池——通过放射性同位素的衰变持续产生电能，没有移动部件，没有燃烧，也没有充电基础设施。
我所描述的设备不是一个使用不同电源的现有智能手机。它是一个从头开始设计的设备，围绕着当前β伏特电池技术可以维持的功耗预算。第一天的性能明显不如2026年的旗舰手机。随着电源架构的进步，这种差距会缩小。
基本物理原理：
氚（H-3）通过β衰变转化为氦-3。
发射出的电子携带的最大能量为18.6 keV，平均能量约为5.7 keV。中微子携带剩余能量，无法回收。β能谱是连续的——电子能量的统计分布，直至终点——这就是为什么平均能量而不是最大能量是功率计算的相关数字。
用于功率计算的氚活度：1居里的氚是每秒3.7 × 10¹⁰次衰变。在每次衰变平均能量为5.7 keV的情况下，1居里的氚释放大约1.6 × 10⁻¹⁹ J/eV × 5,700 eV × 3.7 × 10¹⁰ dis/s = 大约33.8 mW的总β能量。这是可回收功率的上限——转换效率决定了有多少能量转化为电能。
氚的比活度为9,650 Ci/g。因此，一克氚释放大约33.8 mW/Ci × 9,650 Ci/g = 326 W/g的总β能量。商用β伏特电池的转换效率为1-4%，产生大约3.3-13 W/g的电输出——但氚气是弥散的，实际的电池包括一个基底，因此组装好的电池的单位体积功率密度远低于每克氚的功率密度。目前商用产品的实际组装电池功率密度为1-10 mW/cm²。
位于迈阿密的City Labs公司在NRC许可下商业生产氚-硅β伏特电池。他们目前的电池在典型负载下，在有效结面积上产生50-300 μW/cm²的电能。对于当前商用电池，以150 μW/cm²作为中间值进行规划是站得住脚的。
一个多层堆叠电池模块，每层有35 cm²的有效结面积，共有四层——总堆叠体积大致相当于一个传统的电池组——产生大约35 cm² × 4层 × 150 μW/cm² = 21 mW的总输出。考虑到互连损耗和电池间的差异，模块端子的净输出：大约15-18 mW持续输出。
保守的数字——更少的层数，更低的产量电池——大约是5-8 mW。我正在设计第一天的架构，以5 mW持续输出为下限，以15 mW为目标，随着电池技术的成熟。
衰变曲线由半衰期控制
P(t) = P₀ × (1/2)^(t/12.32)
在t = 5年时：P = P₀ × 0.755。在t = 8年时：P = P₀ × 0.629。在t = 12年时：P = P₀ × 0.499。该设备在第12年产生其启动输出的一半。这种输出可以提前数年以高精度预测。没有电池的衰变曲线如此清晰。
衰变曲线和升级周期：
一个以5 mW启动的设备在第12年达到第一天的性能下限。历史上没有任何消费电子设备是围绕着十年可预测、透明的性能衰减而设计的，而不是由软件过时驱动的两年更换周期。这个设备是。
我正在寻找：
我是创始人。我正在进行种子前轮融资，以签署两位联合创始人：一位具有β伏特电池或核电池硬件经验的人，可以领导原型项目。如果你是那个人，或者你认识他们，我很乐意和你谈谈。
如需阅读全文和技术白皮书，或直接联系我，请访问shelvin.com。
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Every smartphone built in the last twenty years assumes the same thing: the battery will be charged once a day. Before I get to the math, sit with this for a moment: what would actually change if a phone never needed to be plugged in?<p>That is what I am building. The power source is betavoltaic — electricity generated continuously from the decay of a radioactive isotope, with no moving parts, no combustion, no charging infrastructure.<p>The device I am describing is not a current smartphone with a different power source. It is a device designed from the ground up around a power budget that current betavoltaic technology can sustain. Day One capability is meaningfully more limited than a 2026 flagship phone. That gap closes as the power architecture advances.<p>The source physics:<p>Tritium (H-3) decays by beta emission to helium-3.<p>The emitted electron carries a maximum energy of 18.6 keV, with a mean energy of approximately 5.7 keV. The neutrino carries the rest and is unrecoverable. The beta spectrum is continuous — a statistical distribution of electron energies up to the endpoint — which is why mean energy, not maximum, is the relevant figure for power calculations.<p>Tritium activity for power calculation: 1 Curie of tritium is 3.7 × 10¹⁰ disintegrations per second. At 5.7 keV mean energy per disintegration, 1 Ci of tritium releases approximately 1.6 × 10⁻¹⁹ J/eV × 5,700 eV × 3.7 × 10¹⁰ dis/s = approximately 33.8 mW of total beta energy. This is the upper bound on recoverable power — conversion efficiency determines how much becomes electricity.<p>Tritium's specific activity is 9,650 Ci/g. One gram of tritium therefore releases approximately 33.8 mW/Ci × 9,650 Ci/g = 326 W/g of total beta energy. Commercial betavoltaic cells at 1–4% conversion efficiency yield approximately 3.3–13 W/g electrical output — but tritium gas is diffuse and the actual cell includes a substrate, so power density per unit volume of assembled cell is far lower than per gram of tritium. Practical assembled cell power densities in current commercial products run 1–10 mW/cm².<p>City Labs in Miami produces tritium-on-silicon betavoltaic cells commercially under NRC license. Their current cells produce in the range of 50–300 μW/cm² of active junction area under typical loading. A mid-range figure of 150 μW/cm² is defensible for planning purposes with current commercial cells.<p>A multi-layer stacked cell module with 35 cm² of active junction area per layer and four layers — a total stack volume roughly comparable to a conventional battery pack — yields approximately 35 cm² × 4 layers × 150 μW/cm² = 21 mW total output. Accounting for interconnect losses and cell-to-cell variation, net output at the module terminals: approximately 15–18 mW continuous.<p>The conservative number — fewer layers, lower-yield cells — lands around 5–8 mW. I am designing the Day One architecture around 5 mW continuous as the floor, with 15 mW as the target as cell technology matures.<p>The decay curve is governed by the half-life
P(t) = P₀ × (1/2)^(t/12.32)<p>At t = 5 years: P = P₀ × 0.755. At t = 8 years: P = P₀ × 0.629. At t = 12 years: P = P₀ × 0.499. The device at year 12 produces half its launch output. That output is predictable to high precision years in advance. No battery ages on a curve this clean.<p>The decay curve and upgrade cycle:<p>A device launched at 5 mW reaches the Day One capability floor at year 12. No consumer electronics device in history has been designed around a decade of predictable, transparent degradation rather than a two-year replacement cycle driven by software obsolescence. This one is.<p>What I'm looking for:<p>I'm the founder. I'm raising a pre-seed round to sign two co-founders: one with betavoltaic or nuclear battery hardware experience who can lead the prototype program. If you're that person, or you know them, I'd like to talk.<p>For the full essay and technical whitepaper, or to contact me directly, visit shelvin.com.