Lithium salt unleashes 93% retention breakthrough in sodium-ion battery tech

Sodium-ion batteries are emerging as a promising alternative to lithium-ion technology.

Lithium salt unleashes 93% retention breakthrough in sodium-ion battery tech

This work tackles the persistent problems of cycle stability and capacity fade in SIBs.

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Researchers in Korea have developed a method to improve the lifespan and performance of sodium-ion batteries (SIBs) by introducing a lithium salt into the battery’s electrolyte. 

The study shows that adding lithium hexafluorophosphate (LiPF6) to the electrolyte resulted in a battery that retained 92.7% of its capacity after 400 charge-discharge cycles. This is an improvement over the typical 80% retention previously reported for similar batteries.

“The addition of LiPF6 to the electrolyte significantly improves the formation of a robust SEI layer on the hard carbon anode,” said the researchers in a press release.

“The scalable synthesis of the LiPF6-added electrolyte highlights its potential for practical SIB applications.”

Addressing key challenges

The work, conducted by a team from the Korea Electronics Technology Institute (KETI) and Kangwon National University, addresses known issues of cycle stability and capacity fade in SIBs.

Sodium-ion batteries are being explored as an alternative to lithium-ion technology. An advantage of SIBs is the global abundance and lower cost of sodium compared to lithium.

This could make them suitable for large-scale energy storage, which is needed to support renewable energy sources. However, the commercial development of SIBs has faced challenges related to the degradation of battery components over time.

A dual-action process

According to the research led by Professor Ji-Sang Yu and Professor Hyun-seung Kim, the lithium salt additive alters the battery’s internal chemistry through a dual-action process. 

Firstly, for anode protection, the presence of lithium salt facilitates the formation of a more stable solid electrolyte interphase (SEI) on the hard carbon anode. This protective layer is less soluble than a standard sodium-based SEI, thereby reducing the decomposition of the electrolyte. 

Secondly, for cathode reinforcement, the lithium ions dope the surface of the O3-type cathode, creating what the researchers term “Li-ion pillars.” 

“The slight surface doping of the O3-type cathode with Li ions creates a structural reinforcement that serves as a pillar, preventing the collapse of the layered structure and reducing gas evolution during cycling,” asserted the press release.

“The formation of a robust SEI layer and the stabilization of the O3-type cathode surface significantly improve cycleability and capacity retention.”

Anode protection and cathode reinforcement

Analysis using differential electrochemical mass spectrometry showed a reduction in CO2 gas evolution, an indicator of electrolyte degradation. 

Post-cycle examination with microscopy techniques revealed a preserved cathode structure and a stable SEI on the anode.

The researchers state that the scalable synthesis of this electrolyte suggests a path toward practical applications for sodium-ion batteries.

This study contributes to the ongoing development of cost-effective sodium-ion battery technologies for a more sustainable energy future.

“The insights gained from this study can guide the development of more efficient and cost-effective sodium-ion battery technologies,” concluded the press release.

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“Future work may focus on exploring other additives and electrolyte compositions to further enhance the performance and stability of SIBs.”

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Aman Tripathi An active and versatile journalist and news editor. He has covered regular and breaking news for several leading publications and news media, including The Hindu, Economic Times, Tomorrow Makers, and many more. Aman holds expertise in politics, travel, and tech news, especially in AI, advanced algorithms, and blockchain, with a strong curiosity about all things that fall under science and tech.