Hybrid Li-Ion Capacitor Operated within an All-Climate Temperature Range from −60 to +55 °C

Abstract

Lithium-ion capacitors (LICs) have been considered as an advanced energy storage system owing to their high energy and power densities. However, their application in a wide temperature range is still a great challenge due to the reduced ionic conductivity of the electrolyte and the poor electric conductivity of the battery-type transition metal oxide electrodes. Herein, an all-climate LIC is wellfabricated with TiNb 2 O 7 @expanded graphite as the anode and activated carbon as the cathode in an optimized electrolyte, which can be operated within a wide temperature range from −60 to +55 °C. Benefitting from the synergetic effect of the improved electrode and electrolyte, the LIC exhibits an outstanding energy density of 119 W h kg −1 and a power density of 5110 W kg −1 based on the total mass of both negative and positive electrodes. Moreover, it can deliver a capacity retention of as high as 42% at −60 °C and function at a superior rate capability at a high temperature of +55 °C, which exhibits an all-climate feature and the potential for wide applications under some extreme conditions.

Nb-Based Mixed Oxides As Anodes for Metal-Ion Capacitors: Progress, Challenge, and Perspective

“…Yin et al assembled AC and TNO@ expanded graphite (TNO@EG) into an all-climate LICs (AC// TNO@EG) with an operating temperature range of −60 to +55 °C. 108 The LICs demonstrated an ED of 119 Wh kg −1 at a PD of 151 W kg −1 . With suitable electrolyte coordination, they exhibited good rate capability at 5 C at −40 °C and could be cycled stably for 340 cycles at 0.5 C; even at −60 °C, 42% of the capacity was maintained.…”

“…Graphite has also been used to improve the electrical conductivity of NBMOs. Yin et al assembled AC and TNO@expanded graphite (TNO@EG) into an all-climate LICs (AC//TNO@EG) with an operating temperature range of −60 to +55 °C . The LICs demonstrated an ED of 119 Wh kg –1 at a PD of 151 W kg –1 .…”

Advances in Low‐Temperature Dual‐Ion Batteries

“…Although highly‐concentrated electrolytes with wider ESWs have been employed to improve the capacity and cycling performance of DIBs, they are not suitable for LT because of the lower ionic conductivity and higher viscosity at higher salt concentration, let alone the salt crystallization at LTs. With the EC content optimization, the 1.0 m LiPF 6 /EC‐EMC (1 : 4, v / v ) electrolyte achieved the balance between low ionic conductivity and the dissociation of lithium salt over a wide temperature ranging from 25 °C to −60 °C, and remained good electrochemical stability in the voltage window from 0 V to 6 V (vs. Li + /Li) [47] . Meanwhile, no crystallization of LiPF 6 could be observed even at the ultralow temperature of −60 °C.…”

“…As one of representatives, nanostructured orthorhombic Nb 2 O 5 (T‐Nb 2 O 5 ) can effectively increase the capacitive contribution, shorten Li + diffusion distance, and facilitate electrolyte immersion, and meanwhile, the carbonaceous combination is beneficial to improve the electronic conductivity of bulk electrode [46] . Similar to T‐Nb 2 O 5 , TiNb 2 O 7 nanoparticles loaded on expanded graphite (TNO@EG) was prepared as the anode to match with AC cathode for assembling all‐climate LICs [47] . Based on the 1.0 m LiPF 6 /EC‐ethyl methyl carbonate (EMC) (1 : 4, v / v ) electrolyte, TNO@EG//AC LICs delivered the capacity of 21 mAh g −1 at −60 °C and 0.05 C (Figure 5), and the capacity retention of 86.7 % after 340 cycles at −40 °C and 0.5 C.…”

“…With the EC content optimization, the 1.0 m LiPF 6 /EC-EMC (1 : 4, v/v) electrolyte achieved the balance between low ionic conductivity and the dissociation of lithium salt over a wide temperature ranging from 25 °C to À 60 °C, and remained good electrochemical stability in the voltage window from 0 V to 6 V (vs. Li + /Li). [47] Meanwhile, no crystallization of LiPF 6 could be observed even at the ultralow temperature of À 60 °C. The resultant TNO@EG//AC LICs exhibited excellent rate performance and long-life cycling under extreme LT conditions.…”