Improvements on High Temperature Lithium Oxyhalide Primary Battery for Downhole Tools Power Applications

Commercial lithium oxyhalide batteries have a very flat voltage curve. It is challenging to determine a battery's remaining capacity during and after powering downhole drilling tools. It is wasteful and environmentally hazardous to dispose of lightly used battery packs. Through innovations in battery cell design and electrolyte formulation, laboratory cells showed multiple voltage plateaus allowing easy estimation of remaining capacity at room temperature. Prototyped DD-size batteries validated the unique feature at high temperatures. If the batteries are used in downhole drilling and measurement tools, non-productive time may be shortened, and costs reduced over time. Small coin cells were assembled in an inert argon gas filled glovebox. The assembled coin cell, lithium metal foil disk, carbon electrode, and other cell components were weighted to determine electrolyte weight accurately. Carbon black electrodes were prepared by coating carbon black paste on nickel foam substrate. After overnight air drying, coated nickel foam was hot pressed to 1 mm thickness at 230 °C. DD-size cells were prototyped at a battery vendor with selected cell configurations. Performance of coin cells and prototyped DD-size cells were measured during constant current discharge tests. Discharge voltage curves of baseline coin cells mimicking commercial battery products were flat at 3.4 until sudden voltage crash at the end of discharge. Coin cells OP-33 and OP-36, with the improved design and electrolyte formula, showed two main voltage plateaus. The higher voltage plateau was around 3.85-3.60 V, and the lower voltage plateau was around 3.50-3.40 V. The sharp voltage transition from 3.60 V to 3.50 V was easy for a user or a battery management system to detect. Capacity percentage in the higher voltage plateau and the lower voltage plateau depends on the energy active chemical compositions of electrolyte. A cell design and electrolyte formulation were selected to prototype scaled-up DD-size cells. Three repeating DD-size cells were discharged at 150 °C. The overall sloping voltage curves and the obvious voltage transition between two discharge stages around 3.5 V can greatly facilitate battery capacity estimation. As of today, there is no commercial high temperature lithium oxyhalide primary battery with such a unique feature of staged and sloping battery voltage shape for capacity estimation. Compared to capacity estimation by charge counting method utilized in some battery monitoring chips, capacity estimation based on voltage change is much simpler, more accurate, and consumes less battery energy without needs of frequent current measurement and charge calculation. Any previously lightly discharged battery pack can be easily determined whether further usage is possible for the next downhole tools power application, which saves cost and reduces battery waste.

FEC Additive for Improved SEI Film and Electrochemical Performance of the Lithium Primary Battery

The solid electrolyte interphase (SEI) film plays a significant role in the capacity and storage performance of lithium primary batteries. The electrolyte additives are essential in controlling the morphology, composition and structure of the SEI film. Herein, fluoroethylene carbonate (FEC) is chosen as the additive, its effects on the lithium primary battery performance are investigated, and the relevant formation mechanism of SEI film is analyzed. By comparing the electrochemical performance of the Li/AlF3 primary batteries and the microstructure of the Li anode surface under different conditions, the evolution model of the SEI film is established. The FEC additive can decrease the electrolyte decomposition and protect the lithium metal anode effectively. When an optimal 5% FEC is added, the discharge specific capacity of the Li/AlF3 primary battery is 212.8 mAh g−1, and the discharge specific capacities are respectively 205.7 and 122.3 mAh g−1 after storage for 7 days at room temperature and 55 °C. Compared to primary electrolytes, the charge transfer resistance of the Li/AlF3 batteries with FEC additive decreases, indicating that FEC is a promising electrolyte additive to effectively improve the SEI film, increase discharge-specific capacities and promote charge transfer of the lithium primary batteries.

A Comparison on the Voltage Output of Al-Cu Primary Battery with its Electrolyte being Coca Cola With and Without Sugar

<div>For the primary battery, different electrolyte will affect the voltage output of the battery. In this paper, the influence of sugar on the output voltage was studied by taking Coca Cola as an example. The results show that there is a certain difference between the effect of electrolyte with and without sugar, but the specific reason is not clear, because the formula of beverage is a secret. Further experiments are needed to draw a conclusion.</div><p> </p><p> </p>