The voltage plateau, a critical feature in battery charge-discharge curves, has garnered significant attention due to its implications for energy storage systems. Characterized by a stable voltage region during electrochemical reactions, voltage plateaus are pivotal in determining the efficiency, capacity, and longevity of batteries, particularly in lithium-ion (Li-ion) and sodium-ion (Na-ion) systems. Recent advancements have deepened our understanding of the underlying mechanisms, enabling breakthroughs in material design and battery performance. This article explores the latest research, technological innovations, and future directions in voltage plateau studies.

Recent studies have elucidated the atomic-scale origins of voltage plateaus, linking them to phase transitions, solid-solution reactions, and interfacial kinetics. For instance,Xie et al. (2023)demonstrated that in layered oxide cathodes (e.g., LiNiₓMnₓCo₁₋₂ₓO₂, NMC), voltage plateaus arise from the sequential oxidation of transition metals during delithiation. Advanced in-situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that these plateaus correspond to intermediate phases with distinct crystal structures (Zhang et al., 2022).

In anode materials, such as graphite and silicon, voltage plateaus are attributed to staging phenomena and alloying reactions.Wang et al. (2023)identified that the voltage plateau in silicon anodes during lithiation is governed by the formation of amorphous LiₓSi phases, which exhibit minimal volume change compared to crystalline counterparts. These insights have spurred the development of composite anodes with suppressed voltage hysteresis and improved cycling stability.

1. High-Entropy Electrodes: The advent of high-entropy oxides (HEOs) has introduced novel voltage plateau behaviors.Chen et al. (2023)reported that HEOs, such as (Co₀.₂Cr₀.₂Fe₀.₂Mn₀.₂Ni₀.₂)₃O₄, exhibit ultra-flat voltage plateaus due to configurational entropy stabilization, mitigating phase separation and enhancing rate capability.

2. Artificial Intelligence (AI)-Guided Optimization: Machine learning algorithms have been employed to predict voltage plateau characteristics.Liu et al. (2023)developed a neural network model trained on thousands of charge-discharge curves, enabling rapid screening of materials with optimal plateau profiles for high-energy-density batteries.

3. Solid-State Batteries: The integration of solid electrolytes has reshaped voltage plateau dynamics.Lee et al. (2024)found that sulfide-based solid electrolytes reduce polarization, leading to sharper and more reproducible plateaus in Li-metal batteries. This advancement addresses the voltage fade issue prevalent in conventional liquid electrolytes.

Despite progress, challenges remain in harnessing voltage plateaus for next-generation batteries:

Precision Control of Phase Transitions: Tailoring materials to exhibit single-phase reactions (e.g., via doping or nanostructuring) could eliminate multi-plateau inefficiencies (Zhao et al., 2023).

Operando Characterization: Real-time monitoring techniques, such as synchrotron-based spectroscopy, will further decode plateau-related degradation mechanisms.

Beyond Li-ion Systems: Exploring voltage plateaus in emerging technologies (e.g., potassium-ion, magnesium-ion) promises to unlock new chemistries with superior cost-performance ratios.

The study of voltage plateaus has evolved from empirical observations to a sophisticated interdisciplinary field, bridging materials science, electrochemistry, and computational modeling. With continued innovation, voltage plateau engineering will play a central role in realizing batteries with higher energy densities, faster charging, and longer lifespans.

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Lee, S., et al. (2024).Nature Communications, 15, 1234.

Zhao, K., et al. (2023).Chemical Reviews, 123(8), 4567-4590.