Lithium-ion battery, can make lithium-ion battery "longevity" secret

Dendrites will appear during the use of lithium-ion batteries, and dendrite breakage will not only lead to battery capacity attenuation and lifetime reduction, but also may pierce the membrane and cause battery short-circuit fire and cause safety problems. In collaboration with Professor Jiajie Liang and Yongsheng Chen from Nankai University and Chao Lai from Jiangsu Normal University, a new optimization strategy was proposed to solve this problem, and a three-dimensional porous carrier of silver nanowire graphene with multi-stage structure was successfully prepared and loaded with lithium metal as a composite anode material. This carrier can inhibit the appearance of lithium dendrites, so the battery can be charged at ultra-high speed, which is expected to significantly extend the life of lithium-ion batteries.

In recent years, many relevant studies in the world have made important breakthroughs in the design and synthesis of lithium anode materials, but so far it has not been able to restrain the dendrite emergence of lithium metal under high current density charge and discharge and the problem of electrode volume expansion, so the long life and large capacity of lithium-ion batteries are still difficult to overcome.

At present, it is one of the effective ways to solve the above difficulties to construct lithium metal composite anode materials by depositing lithium metal into porous collector fluid with three-dimensional network structure. Liang Jiajie said. Based on this understanding, the research group proposed for the first time the ideal three-dimensional carrier material selection and optimization strategy for lithium metal anode to achieve ultra-high current density and ultra-long cycle life. They used graphene macroscopic three-dimensional network as a mechanical skeleton, silver nanowire two-dimensional network as a conductive structure, through a low-cost, compatible with industrial production of coating cold drying method, the preparation of silver nanowire graphene three-dimensional porous support with multi-stage structure, and loaded lithium metal as a lithium metal composite anode material.

Through testing, the specific capacity of the lithium metal composite anode material can reach 2573 mAh/g; in the symmetrical battery test, for the first time, repeated charging and discharging for more than 1000 weeks at an extremely high current density of 40 mAh/cm2 and an overpotential of less than 120 millivolts were achieved. Through electron microscope observation, it can be seen that the multi-stage three-dimensional structure carrier can successfully inhibit the growth of lithium dendrites and the change of electrode volume in the lithium metal negative electrode even under the condition of high-current charging and discharging cycle.