Internal short circuits and the resulting catastrophic battery failure is difficult to detect and can occur under normal working conditions. To enable future high-energy density batteries, particularly lithium metal, an inexpensive internal short protection scheme is required. Here, we selectively remove conductive carbon from the cathode surface, creating a gradient-conductivity electrode. The process etches to a depth of only 5–10 μm and the active particles maintain electrical contact through the backside allowing for otherwise unaltered battery performance. When a lithium dendrite contacts the cathode surface, it will react with the oxide particle rather than contacting the carbon network. The active material now acts as a resistive element limiting the current. During shorting tests induced by abuse charging, cells containing conductivity-gradient cathodes saw a 2x reduction in short circuit current and accompanying temperature rise compared to cells with uniform conductivity cathodes. The reduction in short circuit current thus renders the event harmless. Postmortem analysis shows the dendrites only contact the surface oxide particles, supporting the viability of this gradient conductivity electrode design. Our approach utilizes the intrinsic resistivity of the active material to improve battery safety, is broadly applicable, and incurs no penalty in energy density.

内部短路和由此导致的灾难性电池故障难以检测，并且可能在正常工作条件下发生。为了实现未来的高能量密度电池，特别是锂金属，需要一种廉价的内部短路保护方案。在这里，我们有选择地从阴极表面去除导电碳，形成梯度电导电极。该工艺蚀刻深度仅为 5-10 μm，活性颗粒通过背面保持电接触，从而保持电池性能不变。当锂枝晶接触阴极表面时，它将与氧化物颗粒反应而不是与碳网络接触。活性材料现在充当限制电流的电阻元件。在滥用充电引起的短路测试中，与具有均匀电导率阴极的电池相比，包含电导率梯度阴极的电池的短路电流和伴随的温度升高减少了 2 倍。因此，短路电流的减少使事件无害。事后分析显示枝晶仅接触表面氧化物颗粒，支持这种梯度电导率电极设计的可行性。我们的方法利用活性材料的固有电阻率来提高电池安全性，具有广泛的适用性，并且不会导致能量密度的损失。事后分析显示枝晶仅接触表面氧化物颗粒，支持这种梯度电导率电极设计的可行性。我们的方法利用活性材料的固有电阻率来提高电池安全性，具有广泛的适用性，并且不会导致能量密度的损失。事后分析显示枝晶仅接触表面氧化物颗粒，支持这种梯度电导率电极设计的可行性。我们的方法利用活性材料的固有电阻率来提高电池安全性，具有广泛的适用性，并且不会导致能量密度的损失。