A team co-led by engineers at the University of California San Diego has developed a new design strategy for metal alloy negative electrodes that could significantly improve the performance and durability of next-generation solid-state batteries. The work could help advance the path toward practical, high-performance energy storage for electric vehicles.
The team focused on negative electrodes made of lithium-aluminium alloy. They studied how lithium ions move through different phases of the material – a lithium-rich ‘beta’ phase and lithium-poor ‘alpha’ phase – and how these phases influence the battery’s performance. By adjusting the ratio of lithium to aluminium, the researchers were able to control the distribution of the alloy’s beta phase.
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The researchers found that increasing the proportion of the beta phase significantly enhanced the movement of lithium within the metal alloy – it provided pathways for lithium ions to diffuse up to ten billion times faster than through the alpha phase. The beta phase also led to denser, more stable electrode structures and enhanced channels of lithium diffusion between the electrode and solid electrolyte.
In tests, batteries with beta phase-enriched lithium-aluminium alloy electrodes demonstrated high charge–discharge rates and maintained capacity over 2,000 cycles.
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This is the first study to establish a correlation between the distribution of the beta phase and lithium diffusion behaviour in lithium-aluminium alloys, the researchers noted. The findings could guide the design of future alloy-based electrodes with higher energy density, faster charge times and longer lifespans.
The research has been published in Nature Communications.