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Goel, Anshika

Publications and source records attributed to Goel, Anshika.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Importance of High Valence Element Nb in Ni-Rich Layered Cathodes for High-Voltage Lithium-Metal Batteries

Ni-rich layered cathode materials have attracted extensive attention due to their higher energy density and technological maturity in commercialization. As the nickel content is raised, especially surpassing 80%, the increased energy density comes with the tradeoff of diminished thermal stability and increased electrochemical structural instability of the cathode. Compared with Co, Al, B, and Ta, the introduction of high valence element Nb significantly improved the electrochemical cycling, delivering a capacity of 202 mAh/g, corresponding to a capacity retention of 92% after 200 cycles tested at 45 °C. Further, the ex situ differential scanning calorimetry and in situ isothermal microcalorimetry demonstrate that the Nb-modified cathode has the potential to enhance the safety of ultrahigh nickel (Ni) NMCs and displays remarkable resilience to extensive cycling by inhibiting high-temperature decomposition reactions and exhibiting a lower heat flow during electrochemical cycling.

25 ENERGY STORAGE↗
DOE OSTI2021

Al Substitution for Mn during Co-Precipitation Boosts the Electrochemical Performance of LiNi 0.8 Mn 0.1 Co 0.1 O 2

We report nickel-rich layered oxides, such as LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC 811), are considered as one of the most promising candidates for the next-generation cathode because of their high energy densities and relatively low cost. However, the poor first Coulombic efficiency of NMC 811 leads to around a 15% capacity loss in the first cycle at a cut-off voltage of 4.4 V. Moreover, the structure degradation during cycling results in capacity fading and safety concerns, due to potential oxygen loss after charging. Here, with aluminum substitution for manganese through a developed continuous co-precipitation approach, the electrochemical performance of NMC 811 cathodes has been greatly enhanced. Among different Al% substituted samples, LiNi 0.8 Mn 0.06 Co 0.1 Al 0.04 O 2 cathodes reduced by 50% the first capacity loss of pristine NMC 811(18.0 vs 35.9 mAh g -1 ) and improved the capacity retention from 81.4 to 96.4% after 60 cycles at 0.5C in the voltage range of 2.8–4.4 V.

25 ENERGY STORAGE↗
DOE OSTI2021

What is the Role of Nb in Nickel-Rich Layered Oxide Cathodes for Lithium-Ion Batteries?

Nickel-rich layered metal oxide LiNi 1–y–z Mn y Co z O 2 (1 – y – z ≥ 0.8) materials are the most promising cathodes for next-generation lithium-ion batteries in electric vehicles. However, they lose more than 10% of their capacity on the first cycle, and interfacial/structural instability causes capacity fading. Coating and substitution are possible direct and effective solutions to solve these challenges. In this Letter, Nb coating and Nb substitution on LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) is easily produced through a scalable wet chemistry method followed by sintering from 400 to 800 °C. A Li-free Nb oxide treatment is found to remove surface impurities forming a LiNbO 3 /Li 3 NbO 4 surface coating, to reduce the first capacity loss and to improve the rate performance. Furthermore, Nb substitution stabilizes the structure, as evidenced by less heat evolution on heating, thus providing better long cycling stability with a 93.2% capacity retention after 250 cycles.

36 MATERIALS SCIENCE↗