A k Descriptor to Design of Current Collectors for Anode-Free Sodium Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 40696969.
- Also identified by DOI 10.1002/adma.202504760.
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Abstract
The anode-free strategy enables exceptionally high energy density in rechargeable metal batteries, but the lack of theoretical frameworks impedes current collector design. Here, this study mathematically derives three critical parameters: dielectric coefficient (ɛ), ion mobility (µ_C), and the change of concentration (δC_C), and introduces a quantitative descriptor, k, which serves as a benchmark for evaluating current collector efficiency. Experimentally, a carbon nanotube (CNT)-based current collector is fabricated with minimized ɛ, enhanced δC_C (nano/micro-Sb particles), and µ_C (sodium carboxymethylcellulose, CMC-Na). The optimized design achieves remarkable cycling stability-over 24 months at 0.25 mAh cm<sup>-2</sup> and 0.5 mA cm<sup>-2</sup>, and 12 months even at a high areal capacity of 20 mAh cm<sup>-2</sup>. The lowest k value aligns with half-cell tests, validating this theory. This work establishes a quantitative framework for designing high-efficiency anode-free sodium battery current collectors.