Page 87 - Read Online

Wang et al. Soft Sci 2024;4:32 https://dx.doi.org/10.20517/ss.2024.15 Page 11 of 27

through the ceramic material, elevating the temperature on both sides of the TEG until a new equilibrium
was established. By conducting comparative experiments with a natural cooling system without TEC (N-C
cooling model) and a forced cooling system without TEC (F-C cooling model), the study results showed
that under a 3C discharge rate, the battery module combined with TEC and F-C cooling technology had a
maximum temperature of only 338.43 K, which was lower than the 343.52 K observed in the F-C cooling
model and the 351.30 K in the N-C cooling model. The energy consumption analysis shows that the pure
TEG exhibits the highest energy waste at 26.64 J. The FC-313 K + TEG-313 K (TEG coupled with FC, both
at 313 K) consumes 15.95 J, while the FC + TEG-313 K (FC coupled with TEG at 313 K) is the most energy-
efficient, using only 12.38 J, making it the optimal choice for TEG temperature control.

BTMS based on TEC and liquid cooling
Liquid cooling systems use a liquid with high thermal conductivity as a medium to directly or indirectly
dissipate the heat generated by the battery. In the design of liquid cooling structures, the battery is either
directly immersed in the cooling liquid for heat dissipation or heat is transferred indirectly through a
cooling plate. Indirect cooling involves transferring the heat generated by the battery to a cooling plate,
which then dissipates the heat to the liquid [64,65] . Liquid cooling is currently the mainstream method for
BTMS cooling due to its high thermal conductivity and efficient cooling capability, making it suitable for
overall heat dissipation of high-power battery packs and improving temperature consistency within the
battery pack. However, liquid cooling systems face challenges such as localized overheating, complex
structure, and thermal safety of high-power batteries. Therefore, further research and optimization are
needed in the design and thermal safety aspects of liquid cooling systems [66,67] .

The combination of TEC and liquid cooling in BTMS offers multiple advantages including efficient heat
dissipation, precise temperature control, energy efficiency, environmental friendliness, safety, and
adaptability, making it one of the important directions for the future development of thermal management
technology in areas such as electric vehicles [57,68] . Liu et al. introduced a novel BTMS integrating TEC
(TEC1-12703, L × W × H is 40 mm × 40 mm × 5 mm) with liquid cooling and experimentally calibrated the
[37]
model . Figure 6A depicts the physical model with eight battery cells of 100 Ah, each composing the
battery pack in the BTMS. The TEC’s cold side is mounted on the battery cells to absorb their heat, while its
hot side is connected to a water jacket for effective heat dissipation. Eighteen pairs of thermocouples are
placed on the battery surfaces, with nine pairs on each side. Figure 6B shows the temperature distribution of
the eight batteries with only liquid cooling, where the average surface temperatures of the first, last, and
other batteries are 315.7, 318.9, and 318.3 K, respectively. Figure 6C illustrates the temperature distribution
of the batteries with TEC combined with liquid cooling, with average surface temperatures of 312.2 K for
the first battery, 311.4 K for the last, and 311.5 K for the others. The results demonstrate that TEC cooling
effectively reduces battery temperatures to below 313 K, achieving an average temperature variation of less
than 1 K, which is significantly lower than the scenario without TEC cooling. Troxler et al. investigated the
influence of artificially induced temperature gradients on battery performance, utilizing TEC to create and
sustain temperature gradients in lithium-ion batteries under both isothermal and non-isothermal
[69]
conditions, rather than directly cooling the batteries . The study found that batteries maintained at
temperature gradients exhibited lower impedance characteristics compared to those maintained at
theoretical average temperatures. This phenomenon is attributed to the fine design of the battery’s internal
structure and the nonlinear temperature-dependent nature of charge transfer resistance.

Liu et al. conducted experiments on the cooling effect based on TEC (TEC-12706, L × W × H is 30 mm ×
30 mm × 3.5 mm, the refrigerator power is 60 W and the maximum current is 4.3 A) combined with liquid
[70]
cooling, with the experimental setup consisting of thermoelectric units and cooling plates [Figure 7A] .
The cold side of the thermoelectric unit is connected to the bottom of the battery, while the hot side is