In Situ Mitigation of First-Cycle Anode Irreversibility in a New Spinel/FeSb Lithium-Ion Cell Enabled via a Microwave-Assisted Chemical Lithiation Process

Abstract

First-cycle irreversibility is a major problem that plagues many next-generation nanoscale anode materials which form solidelectrolyte interphase (SEI) layers. Without a method to compensate for this irreversible capacity loss, the full cells will face serious problems. The concept of a lithium reservoir in spinel cathodes was proposed in the early 90s to combat the irreversibility of graphite anodes, but chemical techniques to lithiate spinel have been complex or hazardous. We present in this study (i) a new facile microwave-assisted chemical lithiation technique for spinel oxide cathodes which is capable of inserting one extra lithium per formula unit using less expensive, readily available lithium hydroxide in polyol and (ii) two new advanced lithium-ion batteries combining a prelithiated 5 V spinel Li 1 + x Mn 1.5 Ni 0.5 O 4 or a 4 V spinel Li 1.05 + x Ni 0.05 Mn 1.9 O 4 cathode and a carbon-free FeSb-TiC alloy anode that has a high first-cycle irreversible capacity loss. We show that the extra chemically inserted lithium is necessary to achieve a complete utilization of the cathode capacity. The battery employing the 5 V spinel cathode exhibits good rate capability with an energy density of 260 Wh/kg based on total active mass.

Pre-Lithiation Strategies for Rechargeable Energy Storage Technologies: Concepts, Promises and Challenges

“…However, the additional lithium ions stored at the octahedral sites are usable in the 1st cycle to pre-lithiate the negative electrode and compensate the ALL. Afterwards, the LIB can be cycled in the "standard" potential range, that only the lithium in the tetrahedral sites is reversibly used [137].…”

“…However, the additional lithium ions stored at the octahedral sites are usable in the 1st cycle to pre-lithiate the negative electrode and compensate the ALL. Afterwards, the LIB can be cycled in the "standard" potential range, that only the lithium in the tetrahedral sites is reversibly used [137]. LNMO is a high voltage positive electrode material, which needs charging up to 5 V vs. Li/Li + , in comparison to LMO, where an upper charge potential of only 4.3 V vs. Li/Li + applies [137,138].…”

“…Afterwards, the LIB can be cycled in the "standard" potential range, that only the lithium in the tetrahedral sites is reversibly used [137]. LNMO is a high voltage positive electrode material, which needs charging up to 5 V vs. Li/Li + , in comparison to LMO, where an upper charge potential of only 4.3 V vs. Li/Li + applies [137,138]. This property makes LNMO an interesting candidate for high voltage applications [139].…”

“…In addition, the aforementioned chemical pre-lithiation with lithium iodide is relatively expensive and time-consuming. Therefore, Rosenberg et al developed a microwave assisted chemical over-lithiation method using tetraethylene glycol (TEG) as a reducing agent and hydrated LiOH as the lithium source, which are cheaper than the chemicals mentioned above [137]. Furthermore, this lithiation method does not require any inert atmosphere, because both, TEG and hydrated LiOH, contain water.…”

“…An approach to tackle this problem might be positive electrode pre-lithiation additives. [137,138]. This property makes LNMO an interesting candidate for high voltage applications [139].…”