LiC ₆ @Li as a Promising Substitution of Li Metal Counter Electrode for Low‐Temperature Battery Evaluation

Abstract Li metal, as a counter electrode, is widely used for electrode materials evaluation in coin type half‐cells. However, whether this configuration is suitable for different working conditions has often been neglected. Herein, the large resistance and high cathodic/anodic over‐potential of Li metal at low temperature are highlighted, revealing its incompetence as counter electrode on cryogenic condition. In view of this, a novel LiC 6 @Li composite electrode is developed as a promising substitution for electrode materials evaluation. In the LiC 6 @Li electrode, Li + de‐intercalated from LiC 6 preferentially due to the low interface resistance of LiC 6 , presenting a cathodic/anodic over‐potential of 0.05 V (67 µA cm −2 ) at −20 °C, which is ten times lower than that of Li metal. Moreover, the rapid lithium replenishment into LiC 6 from Li metal enables a stable potential of LiC 6 @Li. Consequently, the LiC 6 @Li‐based half‐cells enabled more precise evaluation of the Li + storage potential and specific capacities of a series of electrode materials at low temperature. As an extension, KC 8 @K is also successfully prepared as a superior counter electrode to K metal. This work proposes a suitable counter electrode for more accurately evaluating electrode materials at subfreezing scenarios, demonstrating the necessity of specialized electrode evaluation systems for particular operating conditions.

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