Porous Graphene Ball Anode for Lithium Metal Batteries
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Solution Overview
Problem
Current lithium metal and sodium metal batteries face issues such as dendrite formation, low energy density, and short cycle life due to poor electrical conductivity and high solubility of lithium polysulfides, leading to internal shorting and safety concerns, which hinder their widespread adoption for high-energy applications.
Innovation Solution
The development of an anode electrode comprising a combination of porous graphene balls and lithium- or sodium-attracting metal particles, where the graphene balls are coated with metals like Au, Ag, Mg, or Zn, forming a layer on a current collector, preventing dendrite formation and enhancing energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal or sodium metal is used as the anode to achieve high capacity and energy density, then the energy density is significantly improved, but dendrites form during charging/discharging cycles leading to internal shorting and safety issues
Solution Approach 1:
A solid electrolyte layer is introduced as an intermediary between the lithium/sodium metal anode and the cathode. This solid electrolyte acts as a physical barrier that prevents dendrite penetration while maintaining ionic conductivity, thereby resolving the contradiction between achieving high energy density through metal anodes and ensuring safety by preventing dendrite-induced shorting.
Solution Approach 2:
A thin solid electrolyte film is applied to the surface of the lithium/sodium metal anode. This flexible thin film layer provides mechanical protection against dendrite formation and penetration while maintaining close contact with the electrode surface, enabling safe operation at high energy density without requiring rigid protective structures.
2Reliability
If a solid protective layer is used to prevent dendrite penetration, then safety is improved, but the solid electrolyte exhibits excessively low lithium-ion conductivity at room temperature
Solution Approach 1:
The solid electrolyte is engineered with specific compositional and structural parameters optimized for room temperature operation. By adjusting the solid electrolyte's composition (e.g., using lithium phosphorus oxynitride, lithium lanthanum zirconium oxide) and density, the patent achieves both high ionic conductivity at room temperature and effective dendrite blocking, resolving the contradiction between safety and power.
3Quantity of substance
If lithium metal anode is used to achieve high capacity, then the specific capacity is improved to 3,861 mAh/g, but dendrite formation occurs upon repeated charges/discharges leading to internal shorting
Solution Approach 1:
A solid electrolyte layer is applied beforehand to the lithium metal anode surface to cushion and prevent dendrite formation during cycling. This protective layer is in place before dendrites can form, preventing the instability and internal shorting that would otherwise occur during repeated charge/discharge cycles, thereby maintaining both high specific capacity and cycle stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The graphene ball-based anode configuration significantly reduces dendrite formation, achieves stable charge-discharge cycles, and increases energy density, addressing the limitations of existing lithium and sodium metal batteries.
Implementation Method 1
The porous graphene ball comprises a plurality of graphene sheets forming into the porous graphene ball
Implementation Method 2
particles or coating of a lithium-attracting metal or sodium-attracting metal at a graphene ball-to-metal volume ratio from 2/98 to 98/2
Data Source
AI summary
Provided is an anode for a lithium battery or sodium battery, the anode comprising multiple porous graphene balls and multiple particles or coating of a lithium-attracting metal or sodium-attracting metal at a graphene ball-to-metal volume ratio from 5/95 to 95/5, wherein the porous graphene ball comprises a plurality of graphene sheets forming into the ball having a diameter from 100 nm to 20 μm and a pore or multiple pores having a pore volume fraction from 10% to 99.9% based on the total graphene ball volume, and wherein the particles or coating of lithium-attracting metal or sodium-attracting metal, having a diameter or thickness from 1 nm to 20 μm, are selected from Au, Ag, Mg, Zn, Ti, K, Al, Fe, Mn, Co, Ni, Sn, V, Cr, an alloy thereof, or a combination thereof.